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CX-401

1. Conductivi Real Salinity Error ty salinity g l by Counted using the for coefficient coefficient 0 5 0 495 0 500 10 00 5 400 5 000 30 00 18 174 15 000 In CX 401 microcontroller takes into consideration the real dependence between the conductivity and salinity what greatly lowers the error There is possibility of counting the salinity in NaCl or KCI because the dependence for this two salts is a bit different 47 The results will be more accurate for homogeneous solutions NaCl KCI Determining the concentration of salts mixture with unknown composition in most cases is counted to NaCl To check the usefulness of water for home or industrial use usually determining of TDS is used To use the conductivity measurement for determining the TDS it is necessary to specify the Wrps coefficient which introduced to the meters memory enables automatic conversion To determine the Wrps coefficient it is necessary to specify the weight of dissolved substances The laboratory method of determining the dissolved solids content consists in taking a given volume of the water evaporating the filtered sample drying it to constant weight in temperatures 103 105 C weighting and counting in volume ratio mg dm The received weight is lower than total dry mass in water because besides the dissolved solids there can be also substances which were not dissolved which are removed by filtering before evaporating Using the conducti
2. 28 1 Time display 66 28 2 Date display 66 28 3 Auto off function 66 28 4 Checking the battery condition 67 28 5 Setting the time and date 67 29 Storage and readout of the results 68 29 1 Storing or printing 68 29 2 Parameters of storing and reading from the memory 68 29 3 Storing the single measurements in the memory 70 29 4 Storing the measuring series 70 29 5 Reviewing of the results 71 29 6 Deleting the stored results 71 30 Printouts on the printer 72 30 1 Printout of the result single or serial 72 30 2 Printout of the results stored in the memory 73 31 Power source and changing the battery 73 32 Co operation with the PC 74 34 Technical data 75 33 Equipment 78 I Introduction 4 1 EXPLOITATION NOTICES Dear User We present you a device distinguished by accuracy according to the technical data and by a high stability of the displayed results We believe that the measurements will not cause you any trouble and that the meter will operate without any inconvenience Wide range of additional functions requires careful reading of the manual in other case some of the features may stay unused or using the meter may cause you a troubles The employing of good quality electrodes cells and probes and their replacing after a suitable time ensures obtaining of high measuring parameters We want to call your attention to the fact that this equipment has a much shorter working life than the meter Typical symptoms of an
3. t concern all of the solutions In some cases after exceeding some salinity value the conductivity starts decreasing The temperature has also a great influence on the results of a conductivity measurement which increases together with the temperature growth The measured conductivity may be displayed as salinity in g l of NaCl or KCI assuming that the measured liquid includes homogeneous salt The electrode s surface and the distance between them have decisive influence on the so called constant K value of the cell This value has a great influence on the accuracy of the measurement Depending on the measured conductivity value cells with constant K 0 1 cm up to 10 cm are used During the measurement the meter multiplies the measured value by the constant K introduced to the meters memory and displays the result in units of conductivity uS cm or mS cm By the result a shortened symbol of the unit is displayed uS or mS The conductivity is changing together with temperature and salts concentration To make the comparing of the results possible the measured value is counted by the meter to the value which responds to measurement in 25 C Measurement in this temperature is most accurate In other temperatures there is so called temperature compensation used this means that there are some counting made by the meter which take the actual measured temperature and a coefficient under the consideration This coefficient describes how much
4. 25 ATMOSPHERIC PRESSURE MEASUREMENT The meter enables atmospheric pressure measurement To read it s value one should turn the meter on by pressing the button with button choose the oxygen concentration mode O2 press the button till moment of displaying in the lower row of LCD the Fr pressure sign in the upper row the value of the pressure in hPa will be displayed pic 26 Pic 26 return to the measuring mode by pressing the button 63 VI ORP and temperature measurement 64 26 ORP VOLTAGE MEASUREMENT Multifunction meter CX 401 is accurate mV meter Oxidation Reduction Potential The measurement may be done with special redox electrode or during titration The result may be checked after choosing the mV mode with button pic 27 a pantai dHe cond pH O time Pic 27 27 TEMPERATURE MEASUREMENT The temperature measurement is done as follows to the Chinch connector connect the temperature probe by pressing the button switch the meter on put the temperature probe to the measured solution wait till the stabilisation of the value and read the lower row of numbers The meter co operates with the PT 1000 probe Depending on its class the accuracy of the measurement changes NOTICE break in the circuit of the temperature probe switches the meter to the manual temperature compensation mode It is signalised by changing the symbol to symbol On the displ
5. membrane must be free of any cracks appearing of electrolyte drops or white spots when dry Before the measurement the electrode should be activated by storing in distilled water for about 15 minutes Strongly polluted wastewater causes after some time clogging of the membrane This is revealed by the impossibility of calibrating of the device at 100 oxygen content the calibration range becomes too narrow In both cases the membrane should be replaced according to the manufacturer s instructions When replacing the membrane and replenishing the electrolyte it is important to pay attention weather there are no air bubbles in the container beneath of the membrane because otherwise the measurements will be false In that case the twisting of the sensor should be repeated after refilling the electrolyte In order to obtain a stable result there must be some awaiting time before making the reading According to the sensor s manufacturers that is about 1 1 5 min depending on the thickness of the membrane The accuracy of the measurement is connected with the temperatures of calibration and measurement The greater the difference of these temperatures the greater the measurement error The used sensors require a two point calibration in a zero O2 saturated solution and an optional solution most often a 100 saturated one Clean water contains about 60 80 oxygen Waste water and chemical solutions are in general less saturated with oxygen but liqu
6. memory If E r symbol will be displayed it is necessary to check the introduced value of the sample solution exit the calibration mode by pressing the button mV time Pic 17 The meter is calibrated and ready for the measurement 15 2 3 Calibration with manual temperature compensation To calibrate the meter it is necessary to turn the meter on with the button choose the measurement of conductivity subchapter 13 1 disconnect the temperature probe and simultaneously press the wo buttons In lower row of LCD a 25 OC value will appear introduce the value of the sample solution chapter 15 2 1 immerse the conductivity cell in the sample solution and hold it at least 1cm away from the bottom and walls of the vessel The measuring cell should be completely filled with the sample solution and shouldn t include any air bubbles the electrode s surface should be evenly moistened with lab thermometer measure the temperature of the sample solution and bring it to 25 C press and hold the button till the CAL symbol pic 17 will appear on the display wait till stabilisation of the result and press the button Pulsating of the result informs about storing it If E r sign will be displayed it is necessary to check the entered value of sample solution exit the calibration mode by pressing the button The meter is calibrated and ready to work air bubbles may be removed by moving the immer
7. one has to choose the way of collecting the measurements p 29 2a enter the time interval p 29 2b delete the stored results starting from the chosen one p 29 6 exit the setting mode by pressing the button Return to the measuring mode by pressing the button with button choose the function which results one wants to store with button start taking the series The measurements will be stored starting from the first free number Taking the series is signalised by blinking frame round the symbol of function which results are stored Before each storing of the result the number of measurement will be displayed for a moment The taking of the series may be stopped by pressing or button or by filling the memory If taking the series was stopped earlier than 200 number one may start to take the next series till the end of memory 71 29 5 Reviewing of the results Reviewing of the stored results is started from the measuring mode by pressing and holding the EA button until the number of last stored result on turns with it s value will be showed Every pressing of the or button shows the next or previous number and result with time and date if FLL function was chosen p 29 2 d In this mode the buttons work with repetition and after longer holding the numbers change very quickly till stopping on the highest or lowest number The reviewing mode may be left by pressing the button 29 6 Deleting the
8. oxygen saturation is used solution of NazSO3 and second with 100 oxygen saturation It can be prepared by aeration of water for more than ten minutes When using this solution it should flow or be stirred The method of preparing both solutions is described in detail in the users manual for the oxygen sensor A simplified calibration for 100 Oz saturation can be carried out in the air without immersing the sensor in water Before that the membrane must be wetted with water for several minutes It is assumed that the O2 content in the air correspondents to 100 saturation what enables a simplified calibration to be carried out The one point calibration is done only in the solution with 100 oxygen saturation 58 Starting the calibration under the chosen sensor number deletes the characteristic stored in memory under this number If after choosing the sensors number and entering the calibration mode one will exit this mode the stored characteristic will be deleted and standard characteristic will be applied To calibrate the meter one should place the sensor in the vessel with 0 saturation solution choose the saturation in measurement according to chapter 21 2 press and hold the button till appearing in the left lower corner of display a CAL symbol after the stabilisation of result press the button The result will pulsate what informs about storing the value of calibration at this same time in the upper row of L
9. recommended to immerse the cell in distilled water with washing up liquid and than wash it in distilled water 44 18 2 Conductivity measurement with automatic temperature compensation In case of measurement with automatic temperature compensation one should connect the conductivity and temperature probes to the right connectors F1 and t pic 2 turn the meter on with button choose the conductivity measurement and the unit point 13 1 if the conductivity cell wasn t calibrated earlier make the calibration according to chapter 15 control or change the value of the temperature coefficient a Place both probes in the measured solution the conductivity cell can t touch the walls and bottom The measuring cell should be completely filled with the sample solution and shouldn t include any air bubbles the electrode s surface should be evenly moistened wait till the stabilisation and read the result pic 20 Pic 20 Notice in case of exceeding the value of temperature taken during compensation into consideration the result starts blinking although the conductivity measuring range wasn t exceeded If near the value a symbol is displayed instead of 6 it informs that the temperature probe is broken or inaccurately connected air bubbles may be removed by moving the immersed cell To make the moistening of the electrodes easier it is recommended to immerse the cell in distilled water with washing
10. stored results To delete the stored results one has to press and hold the putton with buttons or set the number of measurement from which we want do delete the memory press the button what will delete the stored results from the chosen one till the end of the memory On the display in the place of results there will be sign displayed what confirms the deleting to exit the reviewing mode press the button In case of using all 200 numbers of memory more results won t be stored To store new results it is necessary to delete the old ones acting as it was described above If one wants to clear all the memory the deleting should be started from the first number 72 30 PRINTOUTS ON THE PRINTERS In upper wall of the meter there is a RS 232 input which enables joining the meter with printer To connect a printer with Centronics connector it is necessary to use an adapter El 401 which is offered as additional equipment The adapter is connected with the meter by the RS 232 connector pic 2 and with the printer by standard cable There is possibility to print the measured value or the results stored in the memory If the printer is equipped with serial RS 232 input a special cable 4XX PC offered as additional equipment is required 30 1 Printout of the result single or serial To print the result of the current measurement one should connect the printer with the meter as described above switch the met
11. the measured solution if the electrode wasn t calibrated or already was used for a long time the calibration should be done chapter 8 During measurements in a vessel one shouldn t touch the bottom and the walls with the electrode The best way is to use an electrode stand using a laboratory thermometer measure the temperature turn the meter on using the button using the button choose the pH function with buttons enter the value of measured temperature wait till the stabilisation of the value and read the result Caution simultaneous pressing of amp and buttons sets the temperature value to 20 C 29 11 NOTICES ABOUT THE TEMPERATURE COMPENSATION AND INTERPRETATION OF pH MEASUREMENT RESULTS The CX 401 meter has a manual and automatic temperature compensation what enables eliminating errors which result from changes of the electrode characteristics under the influence of temperature changes To explain the role of the temperature compensation it is important to remind that pH meter is an mV meter which displays voltage counted to pH unit In constant temperature for one pH unit a constant mV value is changed In temperature of 20 C it is 58 168 mV The value of mV on one pH unit changes together with the temperature what is taken into consideration in the formula for k coefficient of the pH electrode k 0 198422 T Taking this change into consideration during measurement is called temperature com
12. up liquid and than wash it in distilled water 45 18 3 Conductivity measurement with manual temperature compensation The measurement with manual temperature compensation may be done in stable work conditions ex during measurements in laboratory especially with use of thermostat or in case of the temperature probe damage Disconnecting the temperature probe switches the meter to manual temperature compensation In case of measurement with manual temperature compensation one should connect the conductivity probe to the F1 connector pic 2 turn the meter on with button choose the conductivity measurement and the unit point 13 1 if the conductivity cell wasn t calibrated earlier make the calibration according to chapter 15 control or change the value of the temperature coefficient a Place the probe in the measured solution the conductivity cell can t touch the walls and bottom The measuring cell should be completely filled with the sample solution and shouldn t include any air bubbles the electrode s surface should be evenly moistened measure the temperature of the solution and introduce it s value with the buttons after the stabilisation read the result pic 21 Notice simultaneous pressing of and buttons sets the temperature to 25 C Pic 21 air bubbles may be removed by moving the immersed cell To make the moistening of the electrodes easier it is recommended to i
13. 00 14 000 The values of pH buffer solutions entered by the users are stored in the meter s memory till their changing to others Some of the sample solutions made according to norms may differ between on the third decimal place In very accurate measurements the user may not use the mode with values of sample solutions according to NIST but the mode which enables changing the values of stored buffers Before calibration one has to change them to the accurate value of used sample The range of introducing the pH values of the buffer solutions in the individual points of calibration is quite wide what enables to use buffer solutions with values which differ from the ones set by the producer For example buffers with value 2 00 pH 7 00 pH 9 00 pH and 12 00 pH may be used In every case the introduced buffer solution will be automatically recognised by the meter 19 Together with the temperature change value of the pH buffer solution changes The producers often give the values of the solutions in few temperatures This data may be used and the meter may be calibrated in other temperature than 20 OC by introducing to the meters memory value of the buffer which responds to the chosen temperature 8 2 Automatic change of the pH value of buffer solution In this mode 5 constant sample solution values according to NIST are used In the meter s memory a table with dependence between the temperature and pH values for this 5 sample so
14. CD a corrected value of the measurement 0 will be displayed Take the sensor out wash it accurately in distilled water and put it into 100 oxygen saturated solution ensuring the liquid flow or leave it on the air after the stabilisation of the result press the button The result will pulsate what informs about storing the calibration data at this same time in the upper LCD row corrected value of the measurement will be displayed 100 enter the measuring mode by pressing the button If after pressing the button the meter can t detect the value of the sample solution 0 or 100 in the place of result for a moment an Er sign will be displayed pic 25 In this case it is necessary to check the condition of the membrane and the used solutions Pic 25 59 24 OXYGEN CONCENTRATION MEASUREMENT Before starting the oxygen concentration measurement the meter should be prepared for work chapter 6 and the oxygen sensor calibrated chapter 23 As mentioned the measurement in saturation does not require additional measurements associated with the temperature salinity and atmospheric pressure Although the measurement in mg l used more frequently depends on those factors This influence is corrected automatically by the device taking into the consideration the temperature value measured by the sensor or in case of manual compensation value entered by the user The oxygen sensor is equipped with an additional system co
15. F and t in the meter pic 2 if the function of automatic correction of the influence of temperature on pH value of the buffer solution isn t used measure the temperature of the buffer solutions and bring it to the temperature given by it s producer so to reach the value set in the meters memory The order of using the buffer solutions may be chosen freely 24 After choosing the number of electrode according to the point b press the button and start the calibration on the buffer solutions Under each of the three numbers of electrode one may calibrate next electrodes in pH buffers with different values after earlier setting those values and storing them under the chosen number If the used buffer solution has identical value as this displayed or this buffer isn t used the value should be left without changing The meter takes under the consideration only the detected during calibration values of buffer solutions 8 4 Calibration with automatic temperature compensation After preparing the meter to the calibration it is necessary in pH function to a press and hold the button till the appearance of the CAL pic 7 symbol on the display the old parameters of calibration are deleted b put the electrode and the temperature probe to the buffer solution wait till stabilisation of the result The result may be different than pH value of the buffer solution Pic 7 After stabilisation of the result press the am
16. ICAL DATA Accuracy 1 digit pH measurement 2 000 16 000 pH 0 001 0 01 pH 0 002 pH INPUT IMPEDANCE 1012 Q TEMPERATURE COMPENSATION manual automatic RANGE OF COMPENSATION 5 0 110 0 OC pH ELECTRODE CALIBRATION automatic in 1 5 points RANGE OF RECOGNITION AND ENTERING OF THE pH BUFFER SOLUTIONS point 0 800 2 100 3 900 4 100 6 800 7 100 8 900 9 400 11 500 14 000 AUTOMATIC CHANGE OF THE pH BUFFER VALUE TOGETHER WITH THE TEMPERATURE CHANGE FOR SAMPLES CONSISTENT WITH NIST table page 19 INRANGE 0 60 C THERMAL STABILITY OF ZERO 0 001 pH C mV measurement D ee oe rl 1 digit 1000 1000 mV INPUT IMPEDANCE 1012 Q CONDUCTIVITY MEASUREMENT Accuracy 1 digit 76 Frequency 0 000 19 999 uS cm 0 001 0 01 uS cm 40 1 100 Hz 20 00 199 99 uS cm 0 01 0 1 uS cm 0 1 1 kHz Accuracy given for the end value of the range Ranges of frequency changes were given for constant K 1 For other values of the constant K the values will change proportionally to changes of this constant TEMPERATURE COMPENSATION COMPENSATION RANGE CONSTANT K RANGE a COEFFICIENT RANGE TDS COEFFICIENT RANGE MEASURING RANGE KCI MEASURING RANGE NaCl PROBE CALIBRATION manual automatic 5 0 70 0 C 0 010 19 999 cm 0 00 10 00 C 0 20 1 00 0 200 g l 0 250 g l one point 1 by entering the constant K of the probe 2 using the calibratio
17. ON WITH THE PC Connecting the meter with a PC enables storing data directly on the computer what eliminates the limitation to 200 results The PC should be equipped with serial RS 232 connector typically COM2 configured for 9600 b s 8 bit 1 even bit 1 stop bit lack of steering the transmission On the picture 2 there is the way of joining the meter with the computer showed On the right side of the picture there is the way of joining the cables with the 9 or 25 pin plug with relevant pin numbers For the transmission a special software prepared by our company may be ordered or residential Windows program HyperTerminal in menu Accessories Communication If it isn t there it should be installed from the Windows installation CD The program should be configured with option direct connection with port COMx After setting the option rt to an after pressing the button transmission of the currently measured value and temperature to the PC will start in the format which depends of the chosen parameters 5 r int and FLL On the pic 32 a scheme of connecting the meter with a PC is showed On the right side of the picture way of connecting from the side of computer for 9 and 25 pin connector with the correct numbers of pins Cable 4XX PC available as Jack 2 5mm Connector 9 pin 25pin ORONWNH NOOARNON O option Pic 32 Caution the meter and PC should be switched on after connecting the cable 75 33 TECHN
18. RAMETERS 22 1 Changing the number of probe The meter may store calibration characteristics of 3 DO probes Before the calibration or measurement it is necessary to choose the required number of probe It is done as follows in the measuring mode press the button till appearing in the lower row of LCD Pr i Pre or Prj symbol pic 22 with buttons choose the required number of probe enter the measuring mode by pressing the button Pic 22 The symbol above the probe s number informs Lic under this number there is no characteristic stored and manufacturers settings are applied SEE under this number there are the calibration results stored 53 22 2 Changing the unit The measurement result may be displayed in of the oxygen saturation or in mg l To choose the unit one should in the oxygen measuring mode press the button till displaying in the lower row of LCD une unit sign with buttons choose in the upper row the symbol measurement in of oxygen saturation mg l measurement in mg l pic 23 Pic 23 return to the measuring mode by pressing the button 22 3 Salinity influence compensation Salinity of the solution decreases the oxygen solubility in water and requires taking into consideration during measurements in mg l 1 g l change of salinity changes the oxygen saturation for about 5 The meter enables entering the salinity value in g l and counts the change of oxyg
19. TY CELL 14 1 The cell choice The conductivity measuring range in CX 401 meter is 0 1999 mS cm The meter co operates with conductivity cells with constant K 0 010 19 99 cm 1 and BNC 50 connector Depending on the required measuring range it is necessary to choose the right cell with constant K which enables receiving correct results Beyond the range the cell looses it s linearity and the results have greater error Accurate measurements in the whole range are possible with use of 3 different conductivity cells Depending on the expected measuring range one may choose the correct cell using the chart below stata K 10 1 0 ApSlem 10pSicm 100pSlem ImSiem 10mSiem 100mSiem 1 Slem 2Slem y Pic 14 Dependence between the measuring range and constant K of the used conductivity cells The cell with constant K 0 1 cm should be used for measurements of ultra pure and redistilled water Those waters after contact with air very quickly change their conductivity so their pouring into vessels for measurement with dip cell immersing may cause errors For accurate measurements it is necessary to use flow through probe with build in temperature probe what enables measurement of water which flows directly from the container 37 14 2 The conductivity cell maintenance To receive stable results it is advised to store the cell for few hours before the measurement in water especially this is required in case of distilled wa
20. WATERPROOF MULTIFUNCTION METER CX 401 USER S MANUAL WATERPROOF MULTIFUNCTION METER CX 401 Before use please read the instruction carefully TABLE OF CONTENT l Introduction OaARWN gt Exploitation notices The characteristic of the meter What is the meter designed for Outside view Switching the meter on and off Preparation to work 6 1 Choosing the kind of temperature compensation 6 2 Changing the resolution of the measurement ll pH measurement 7 8 10 11 Preparation of the pH electrode Calibration of the pH electrode 8 1 Introducing the pH values of the buffer solutions 8 2 Automatic change of the pH value of buffer solution 8 3 The actions during calibration 8 4 Calibration with automatic temperature compensation 8 5 Calibration with manual temperature compensation Changing the electrode and checking it s condition 9 1 Checking the electrode s condition pH measurement 10 1 Measurement with automatic temperature compensation 10 2 Measurement with manual temperature compensation Notices about the temperature compensation and interpretation of the results lll Conductivity and salinity measurement 12 13 14 15 16 17 18 Basic information about the conductivity measurement Preparation to work 13 1 Choosing the unit 13 2 Entering the Wrps coefficient Choice and maintenance of the conductivity cell 14 1 The cell choice 14 2 The conductivity cell
21. age is different than this for clean water or for meats or soil It should fulfil the following conditions a it must be easy to wash so an electrode with plastic unremovable housing shouldn t be used Deposits fats and chemical compound will precipitate on the junction what will disable the measurement or falsify the results b shape of the membrane should enable easy washing For measurements in sewage the best shape of membrane is a cylinder shape c junction in the electrode for sewage has more holes what enables easy flow of the electrolyte and makes clogging difficult d during measurement of sewage or liquids with deposits with electrode which shape enables refilling of the electrolyte the hole for refilling should be opened to use the difference of pressures to clean the junction 31 III Conductivity and salinity measurement 32 12 BASIC INFORMATION ABOUT THE CONDUCTIVITY MEASUREMENT The conductivity measurement is based on applying a voltage with proper frequency between two electrodes and measuring it In the CX 401 the frequency depends on the measuring range and may vary from 100 Hz up to 10 kHz Depending on the kind of the measured liquid its concentration and the temperature the voltage flow is easier or harder The conductivity result indirectly informs about the salts concentration in the measured liquid The greater is the salt concentration the bigger is the conductivity KCI NaCl This dependence doesn
22. asurement 0 001 pH For the conductivity measurement Lo resolution of the measurement 3 digits ti resolution of the measurement 47 digits For the oxygen measurement Lo resolution of the measurement 1 or 0 1mg I h resolution of the measurement 0 1 or 0 01 mg l Return to the measurement mode by pressing button 13 ll pH measurement 14 7 PREPARATION OF THE pH ELECTRODE The electrode should be prepared to work according to the producer instructions If the instructions weren t given please follow the steps new electrode should be put into distilled water or in saturated KCI solution for about 5 hours Before starting the measurements protecting rings if used in this kind of electrode should be removed The ring placed on the junction lower part of the electrode should be moved up along the electrode s body and the upper which protects the KCI refilling hole down along the body Removing the lower ring is essential in other case the electrode won t measure Upper ring should be removed during measurements of high temperature solutions or to protect the junction during measurements in solutions with deposits or oils during measurements in laboratory it is advisable to use an electrode holder after every measurement the electrode should be washed in distilled water excess of liquid on the electrode should be removed by gentle touching the glass with a tissue paper after work the electrode s
23. ay the value of the temperature entered by the user is displayed Blinking 50 C value during measurement in positive temperatures informs about short circuit in the temperature probe 65 Vil Other 66 28 CLOCK DATE AUTO SWITCH OFF FUNCTION After choosing the time mode with button the meter will display the actual time By pressing the button one may display the date auto off time and battery condition 28 1 Time display The hour is displayed in two rows In the upper one the hour and minutes are displayed and in the lower one seconds The way of changing the hours is described below There is no way to set the seconds they are deleted after pressing the button 28 2 Date display The date is displayed as follows Month Day Year pic 28 In the upper row the month and day are displayed and in the lower the year in two digits form year 2000 00 year 2001 01 etc Pic 28 28 3 Auto off function About choosing the auto off function informs a fat Auto OFF symbol In the lower row the time of switching off in minutes is displayed the time is counted from the last pressing of any button The value is changed by or buttons If after choosing the time 1 minute one will press the OJ button a symbol will be displayed instead of numbers This will deactivate the auto off function Exit from this function is after pressing the button The auto off function is active only during work on batter
24. cording to the point d d After choosing the St user setting symbol one should start checking and eventually changing the stored values of calibration points To do so one should press the button In the lower row af symbol will be displayed point one of calibration and in the upper row value of the buffer pic 6 If one uses buffer solution with value a bit different than this displayed one using or buttons bring the displayed value to the value of used buffer solution Range of changes for each calibration points is given in the table 2 593 Pic 6 To pass to the second point of calibration press the button in the lower row a F7 symbol will be displayed point 2 and in the upper row the stored in this point value of buffer solution When checking or changing the value in the next steps please follow the instructions given above After the end of introducing the pH values of buffer solutions using the button return to the choosing the calibration points mode fut t St or by next pressing the enter the pH measuring mode During next calibrations if the values of the previously used buffer solutions haven t changed the actions described in this point may be omitted e Prepare the electrode for work acting according to it s producer instructions than mark it with the number chosen in the meter symbols t Etc ELJ connect the prepared combination electrode and temperature probe to the right connectors
25. cy of this procedure depends on the demanded accuracy number of the measurements carried out conditions in which the electrode was used temperature and value of the measured solutions When the highest accuracy is required it is recommended to use sample solutions with certificates In technical usage buffer solutions are used with lower accuracy but mostly with total values ex 2 00 pH 4 00 pH etc In this manual to make it easier a buffer solution name was used for both buffer and sample solutions For accurate measurements it is necessary to use fresh good quality buffers The first action taken before the calibration is entering the values of used pH buffer solutions to the meters memory This should be done before the first calibration and repeated in case of changing the used buffers to other values During the calibration after immersing the pH electrode and temperature probe the meter automatically detects the value of the used buffer if it was earlier stored in the meter s memory There is possibility of calibration in minimum 1 buffer solution and maximum in 5 The more points of calibration is used the higher is the accuracy in the whole measuring range 16 Calibration in one buffer solution can t ensure high accuracy If only one buffer solution is used it s value should be close to the forecasted value of measured solution If the required accuracy isn t very high and the measurements will be done in the whole range the
26. dition Checking the electrode condition is possible only if the calibration was done To do so in the pH mode the button should be pressed and number of calibrated electrode should be chosen If above the number a bd symbol will be displayed this informs that the electrode has lost its efficiency and in short time its calibration won t be possible It is necessary to prepare a new electrode 27 10 pH MEASUREMENT Before starting the measurement one has to prepare the meter for work chapter 6 and pH electrode chapter 7 Good condition of the electrode is the main condition of correct measurements If the electrode was calibrated and is joined with the meter it is advisable to check whether the number of the electrode is this same as the number of the characteristic chosen from the memory If not the number should be changed according to section 8 3 6 and the resolution of measurement should be chosen according to the chapter 6 2 10 1 Measurement with automatic temperature compensation During measurements with automatic temperature compensation the meter co operates with the temperature probe and measures the temperature of the solution simultaneously with the pH measurement and takes it into consideration during compensation In case of measurement with automatic temperature compensation one should join the temperature probe and the combination pH electrode to the right connectors on the meter F and t pic 2 symbol 6 will b
27. e display is used for switching the meter on and off choosing the measuring function calibration entering the parameters printing and storing the results in the memory 8 The keyboard has the keys as follows to change the function and switch the meter on off short pressing in MODE P CAL mode enables choosing points of calibration to change their value longer pressing of this button enters the calibration mode CAL symbol displayed Short pressing in this mode confirms the calibration result after pressing this button the result is stored the measuring series starts or printing begins after longer pressing of this button the stored results reviewing is possible chooses the entered parameter buttons used for entering the parameters In upper wall of the meter there are inputs with below given symbols F BNC 50 connector for connecting the combination pH electrode Redox electrode or the oxygen probe F1 BNC 50 for connecting the conductivity cell t Chinch input to connect the temperature probe RS RS 232 input for connecting with PC or printer P Power adapter input 9V l IUC CAL L ttc cond mV O time multifunction meter CX 407 waterproof Pic 2 10 5 SWITCHING THE METER ON AND OFF The meter is switched on by pressing the button The meter tests the memory and display on which all symbols are displayed NOOR A089 man 4 ae tes Woodsen CALOF o I DD Pic 3 If
28. e displayed if the electrode wasn t calibrated or was already used for some time it is advisable to calibrate it chapter 8 insert the electrode and the temperature probe to the measured solution During measurements in vessels one should not touch the bottom and the walls with the electrode Best way is to use an electrode stand Turn the meter on by pressing the button using button choose the pH measurement function After the stabilisation read the result Accurate laboratory measurements require using of electromagnetic stirrers NOTICE exceeding of the measuring range is indicated by blinking of the digits on the display 298s 10 2 Measurements with manual temperature compensation Disconnecting the temperature probe from the meter switches the meter to the manual temperature compensation mode symbol is displayed Measurement with manual temperature compensation is similar to the measurement with ATC the difference is that using i buttons one enters the temperature measured with other thermometer This value is displayed under the pH value and is taken into consideration during the compensation The manual compensation may be used during stable conditions ex during pH measurements in the laboratory especially when a thermostat is used or when the temperature probe was damaged During the measurement with manual temperature compensation one should insert the pH electrode to the vessel with
29. e table 7 enter the oxygen measuring mode by pressing the button Measurement in of saturation doesn t require entering the salinity value 55 TERE m m m 1 049 28 16 87 55 34 34 2 100 29 1 17 52 56 34 99 a foe 31 382 se 36 28 5 263 32 1946 59 36 93 fe 319 33 2011 60 37 58 8 429 35 2141 62 38 87 9 485 36 22 05 63 39 52 mr feon f e 2335 6s aor 12 661 39 2399 66 4146 ia fres a1 2529 66 2275 15 845 42 25 93 69 43 40 e 11 66 z 29 17 a 46 64 12 31 29 82 47 28 2 15 56 s3 3305 80 50 63 27 1622 54 3370 T Table 7 Determining the salinity in g l NaCl on the basis of conductivity in mS cm in temperature 25 C 56 22 4 Automatic compensation of the atmospheric pressure influence The value of oxygen saturated in water determined in mg l depends directly on the atmospheric pressure value this means that 10 pressure change causes oxygen saturation change for 10 The meter ensures automatic compensation thanks build in atmospheric pressure sensor This influence is automatically counted during measurements in mg l There is possibility of reading the atmospheric pressure value in the oxygen measuring mode press the button till moment of appearing in the lower LCD row Fr pressure sign pic 24 in the upper row a value of atmospheric pressure will be displayed in hPa Pic 24 enter the oxyg
30. easurement is possible only with simulated or natural measured water flow The essential feature of our products is their low failure frequency However if your meter will fail our firm immediately performs its warranty repair We wish you a pleasant and trouble free work with our meter ae 2 THE CHARACTERISTICS OF THE METER The multifunction meter CX 401 belongs to the newest generation of measuring devices which offer wide range of additional functions The meter ensures high accuracy and repeatability of the readings Two kinds of power source battery and power adapter enable work in field and long lasting measurements in the laboratory The newest generation electronic elements used in the meter made its memory independent to power supply and have ensured very low power consumption what greatly increases the operation time on 1 battery The meter is equipped with large custom LCD display which enables simultaneous observing of the measured function temperature value and additional symbols which make working easier Waterproof housing makes working in difficult conditions possible Small size and weight make the meter very handy especially during the field work Main features of the CX 401 are high accuracy and stability of the reading automatic and manual temperature compensation pH electrode calibration in 1 to 5 points automatic recognition of pH buffers and standards imposed values of standard solutions
31. easuring mode by pressing the button ECO JAN og UI a et he pH mV oO time z Pic 18 The measurement result will be counted with use of the introduced temperature coefficient a 43 18 THE CONDUCTIVITY MEASUREMENT 18 1 The conductivity measurement without temperature compensation An accurate conductivity measurement should be done without the temperature compensation The measured solution should be brought to temperature of 25 C During the control it is possible to use the temperature probe In case of work without temperature probe it is necessary to introduce the temperature value with buttons One should connect the conductivity and temperature probes to the right connectors F1 and t pic 2 turn the meter on with button choose the conductivity measurement and the unit point 13 1 if the conductivity cell wasn t calibrated earlier make the calibration according to chapter 15 Place both probes in the measured solution the conductivity cell can t touch the walls and bottom The measuring cell should be completely filled with the sample solution and shouldn t include any air bubbles the electrode s surface should be evenly moistened bring the temperature of the measured solution to 25 C read the result after it s stabilisation pic 19 Pic 19 air bubbles may be removed by moving the immersed cell To make the moistening of the electrodes easier it is
32. en measuring mode by pressing the button During the oxygen measurement in of saturation the atmospheric pressure has no influence 57 23 CALIBRATION OF THE OXYGEN PROBE In order to eliminate the measurement error arising from the individual characteristic of the sensor a calibration of the device should be carried out This procedure should be performed always before operation with a new sensor after replacing the membrane or for special requirements concerning the measurement accuracy The probes have a so called signal drift associated with the interval between the calibration and measurement A longer interval decreases the measurement accuracy The calibration is also recommended if the temperature of the tested solution differs greatly from the temperature in which the probe was calibrated because then an additional error arises In this case calibration solutions should be used which temperature is almost the same as the predicted temperature of the tested solutions If it is impossible to calibrate the device the membrane of the sensor must be replaced according to the manufacturer s instruction This situation usually takes place if the membrane is strongly polluted or ruptured sometimes almost invisible After replacing the membrane the sensor should be conditioned in water for 24 hours The used oxygen sensors require one or two point calibration in standard solutions During two point calibration a solution with 0
33. en saturation in mg l 54 22 3 1 Automatic introduction of salinity value The meter enables automatic introduction of measured solution salinity To use this feature one should by pressing the button enter the conductivity measuring function measure the salinity of solution in NaCl accurate description in chapter 19 1 Aer EIES of the salinity result enter the oxygen measuring mode by pressing the button press the button till moment of displaying in the lower LCD row a SAL salinity symbol shortly press the button in the upper LCD row automatically the value of measured salinity in g l will be provided If after pressing the button a Err error sign will be displayed and next the old value of salinity it informs that during the conductivity measurement the unit wasn t changed for g l of NaCl return to the measuring mode by pressing the button 22 3 2 Manual entering of the salinity value The salinity value may be determined on the basis of known conductivity of the measured solution The table 7 gives the real dependence between the salinity and conductivity counted in NaCl To enter the salinity value one should with any conductivity meter measure the conductivity of the solution and from the table 7 read the salinity value in the oxygen measuring mode press the button till displaying in the lower LCD row 5At salinity sign with buttons enter in the upper LCD row the salinity value red from th
34. ensation To start the calibration with manual temperature compensation one has to disconnect the temperature probe Disconnecting the temperature probe switches the meter to manual compensation On the display the entered value of the temperature is displayed not the measured one The f buttons will be unblocked and using them one may enter the value of the solution temperature This value is displayed in the lower row of numbers on the display Next thing is to join the pH electrode with the meter and act according to points a c of the previous section It is important to remember that in case of manual temperature compensation the temperature value entered by the user is taken under consideration Caution simultaneous pressing of both and buttons sets the temperature to 20 C 9 CHANGING THE ELECTRODE AND CHECKING IT S CONDITION If in the memory of the meter there is more than one electrode characteristic one may change the electrode without the calibration This feature is very useful especially when using different kinds of electrodes for sewage and clear water etc or during measurements in the field in case of breaking the electrode One has to connect the earlier calibrated electrode marked with the number and choose the right number of characteristic from the memory according to the steps given in section 8 3 b Et i Etc ELJ symbols After this one may start the measurements 9 1 Checking the electrode s con
35. ent For printing an Interface El 401 Elmetron is required Before starting the work it is necessary to choose the storing or printing function and determine the way of displaying the result 29 2 Parameters of storing and reading from the memory The parameters are changed in the readout mode It may be entered from every measuring function by pressing and holding the button until on the display the number of last stored result will be displayed This number is displayed on turns with the stored result Before starting the storing one has to choose the kind of results collecting on request or as series and also the way of displaying the result Next pressing of the button shows screens with following functions which may be changed a 5Er taking or printing series or single results 6Er cond pH mV O time Pic 30 69 With or button choose in lower row on or ofF symbols pic 30 Choosing nm activates automatic storing of the results and ofF single after every pressing of button b int time interval during series taking pic 31 Pic 31 Value of the time interval is displayed in the upper row of digits and the informative symbol int in the lower row Buttons and are used to set the chosen time in minutes and seconds The shortest time is 1 second and the longest 60 minutes Holding the buttons make changing quicker repetition In case of choosing the 5 amp parameter to off setting
36. ents are caused mainly 98 by the sensor yet not by the device In many cases the troubles result from lack of basic maintenance of the sensor from the user s side It must be remembered that during the measurement the sensor takes oxygen from the environment of the membrane The sensor s manufacturers recommend in their instructions the minimal flow rate of the tested water assuring a stable result If that requirement is not complied the result will regularly decrease During measurements in stagnant solutions the flow can be partly simulated by keeping the sensor in motion with a suitable speed In laboratory conditions i e performing the measurements in a vessel the flow can be forced with a magnetic stirrer Although it must be kept in mind that when measuring low Oz saturation intensive stirring can cause an increase of oxygen content in the tested solution Taking water samples and transferring them to the laboratory can alter the O2 concentration in the samples The best results can be achieved only in conditions which are recommended by the manufacturer of the sensor in the operation manual Long lasting storing of the sensor without performing of measurements above 1 month requires removing of the electrolyte After this period the container must be filled with a fresh electrolyte and the sensor stored in distilled water for about 24 hours 51 A correct measurement is determined by the good condition of the membrane The
37. er on set the printout parameter frt to an chapter 29 2 c choose the printout form chapter 29 2 d and way of printing single or serial printouts chapter 29 2 a turn the printer on if the single kind of taking measurements was chosen every pressing of the button will cause printing the actually measured value temperature and number if taking the series of measurements was chosen after pressing the button printing of actually measured value temperature and number of measurement with chosen time interval will be started If the parameter ALL was set to an together with the value of actually measured result and temperature the date and hour will be printed Printing of the series may be stopped by pressing the or button There are no limits in number of printed results 73 30 2 Printout of the results stored in the memory To print the results stored in the memory join the printer with the meter using the RS Centronics adapter as described on the beginning of the chapter switch the meter and printer on choose the printout format point 29 2 d and way of printing serial or single point 29 2 a enter the results viewing mode point 29 5 with buttons set the number of measurement from which the printing should be started Pressing the starts printing The results of measurements with numbers will be printed In case of setting the 5E parameter to on all results from the set one
38. ftware offered by our company Caution interface El 401 which enables connecting the meter with standard printer and special software for collecting series of measurements on a PC is offered as additional equipment SIS 4 OUTSIDE VIEW On the front wall of the meter there is a LCD display pic 1 on which depending on the chosen function following symbols are displayed result of the conductivity or salinity measurement result of the pH measurement in pH units result of the mV measurement in mV result of the oxygen measurement in or mg l time and date Choosing the function by button is signalised by displayed frame round the right symbol in the lower part of the display cond conductivity pH mV O2 or time Simultaneously with the result a measured temperature value is displayed in OC Symbols of the units are displayed by the results In the oxygen measurement mode there is possibility of reading the atmospheric pressure value eo aa Pic 1 Beside the temperature value a 6 symbol for automatic temperature compensation is displayed or for manual CAL symbol on the left side of the display informs that the meter is in calibration mode After pressing the button all parameters introduced by the user are displayed and also the value of atmospheric pressure measurement in oxygen measurement function If the battery should be changed a symbol is displayed The keyboard pic 2 placed under th
39. ges 10 Combined pH electrode glass membrane Conductivity cell Power adapter 9V Adapter El 401 for connecting the printer with Centronics connector 4XX PC cable Software for collecting large number of data on the PC Adapter for connecting measuring end reference electrode in place of combined one Temperature probe Pt 1000 1 3B with higher accuracy lon selective electrodes 11 ORP measuring electrodes 12 Dissolved oxygen sensor WARRANTY The ELMETRON company ensures a 24 months warranty for the multifunction meter CX 401 number In case of damage the producer will repair the meter within 14 days from the day of delivery The warranty doesn t cover the damages caused by usage not in conformity with the users manual using wrong power adapter mechanical damages and damages caused by repairs made by unauthorised persons The pH electrode conductivity cell oxygen sensor have the warranty of the producer NOTICE Before sending the meter to us please contact the firm by phone or email When sending the meter the used electrode conductivity cell oxygen sensor temperature probe and power adapter should be also included Date of production cceeeeeeeeteeeeeeeees Date of Sale eccccccceceeeeeeteeetceeeeeeeeneeees Date of warranty expiry
40. he TDS value should be counted to weight of the sample equal 1kg 19 3 The measurement of salinity with conversion to TDS The measurement of salinity with conversion to TDS should be done as follows according to chapter 13 1 introduce the Wps coefficient choose the measurement of salinity with conversion to TDS and the displayed unit g l or than act as during conductivity measurement chapter 18 after stabilisation read the result in chosen units g l or 49 IV Dissolved oxygen measurement 50 20 BASIC INFORMATION ABOUT DISSOLVED OXYGEN MEASUREMENT The measurement of dissolved oxygen in water solutions is performed using an oxygen sensor The basic element of the sensor is a Teflon semi permeable membrane which enables the penetration of oxygen contained in the measured solution into the electrolyte inside of the sensor The sensor creates a cell which voltage depends on the oxygen content in the electrolyte The meter enables measurement in of oxygen saturation and mg l The calculation of the mg l value is based on the saturation measurement in and the temperature measurement When requiring high accuracy during mg l measurements the values of salinity and atmospheric pressure must be additionally introduced The saturation measurement in does not depend on these factors The quality of the oxygen sensor has a decisive effect on the measurement accuracy The troubles arising during the measurem
41. he oxygen and temperature probes to the measured solution turn the meter on with button with button choose the oxygen measuring function choose the unit according to chapter 22 2 by accurate measurements in mg l enter the salinity value chapter 22 3 check or simulate the flow of the measured solution wait till stabilisation of the result about 1 1 5 min depends on the probe and read the result 24 2 Measurement with manual temperature compensation To make the measurement with manual temperature compensation one should disconnect the temperature probe from the meter turn the meter on by pressing the button with button choose the oxygen measuring mode choose the unit according to the chapter 22 2 by accurate measurements in mg l enter the salinity value chapter 22 3 insert the oxygen sensor to the measured solution using thermometer measure the temperature of the solution with O buttons enter in the lower row of LCD value of temperature of the measured solution check or simulate the flow of the measured solution after the stabilisation read the result During series of measurements it is recommended to check and correct the introduced value of solution temperature Caution in case of measurements in solutions with low salinity check according to the chapter 22 3 weather the introduced salinity value is 0 00 g l 61 V Atmospheric pressure measurement 62
42. hould be stored in one of the above given solutions The protecting rings should be moved on the junction and upper hole in case of long breaks between the measurements the electrode should be stored after drying in the packaging after taking the electrode of the package the eventual deposit should be removed using water before using the electrode it should be placed in distilled water for about 2 hours if the construction of the electrode enables refilling the electrolyte it should be controlled and refilled periodically by the upper hole in the electrode s body usually as the electrolyte a KCI solution is used CAUTION storing of the electrode in distilled water shortens it s life time and may cause shifting of the zero point 15 8 CALIBRATION OF THE pH ELECTRODE Before starting the measurement with new electrode after long lasting using or before making measurements which require higher accuracy the electrode connected with the meter should be calibrated Results of measurements done without calibration will have a great error The calibration is done on the buffer solutions It depends on comparing pH value of the buffer solutions with the value displayed by the meter and next automatic introduction of correction which is taken into consideration during measurements The calibration should be periodically repeated because during work the parameters of the electrode are changing what influences the accuracy The frequen
43. idation Reduction Potential mV conductivity in uS cm or mS cm dissolved oxygen in water in of saturation or mg l and atmospheric pressure measurement in hPa The meter may be also used for accurate temperature measurement of solutions and air in C The conductivity measurement result may be also displayed in concentration units g l or counted to NaCl KCI or TDS Waterproof housing enables work in difficult weather conditions or in humid environment Multifunction CX 401 meter is being used in food chemical pharmaceutical and energetical industries in water treatment stations laboratories agriculture universities scientific laboratories etc The meter is prepared to work with all types of combination pH electrodes and conductivity cells with wide constant K range equipped with BNC 50 connector It is possible to connect the meter with two electrodes pH measuring and reference by special adapter offered as additional equipment CX 401 co operates with Pt 1000 temperature probe with Chinch connector The meter may collect up to 200 measurements taken as single or series of measurements with set time interval RS 232 output enables connecting the meter wit a PC for sending the data or through special El 401 interface with standard printer what enables printing the data collected in the memory or current results of the measurement In case of necessity of collecting series longer than 200 results it is possible to use special so
44. ids with forced aeration are much more saturated When performing accurate measurements the sensors manufacturers recommend carrying out calibration just before the measurement since after some time the sensor s parameters are changing Even the best oxygen sensors have so called drift about 1 24 h Wide measuring range in multifunction meter CX 401 enables measurements of waters which are permeated with oxygen This situation occurs when in the water plants are blooming and growing in this moment during the photosynthesis process large quantities of oxygen are produced 52 21 THE OXYGEN SENSOR The meter may co operate with galvanic oxygen sensor Conventionally it co operates with the sensor made by ELSENT with accuracy of 1 if the measurement is done in this same temperature as the calibration The accuracy of measurement decreases together with growing of the difference between the temperature of calibration and temperature of measurement It is lt 3 when the difference is 5 C and 5 when the difference is 10 C In case of using another sensor the device requires its adaptation by the manufacturer It must be remembered that the membrane of the sensor should be replaced if it is mechanically damaged or if the device cannot be calibrated The necessary procedures are given in the instruction of the probe s manufacturer Before starting the work please read carefully the information given in chapter 20 22 ENTERING THE PA
45. improper operation of the electrode are deterioration of final result stability it s flowing as well as a higher measuring error Part of the users has problems arising from employing electrodes not being preconditioned before the measurement or making the measurements without removing the shielding ring from the liquid junction or taking measurements with a plugged junction To avoid this situation it is necessary to choose the proper kind of electrode for solutions which are going to be measured ex special electrodes for the sewage liquids with deposits meat cheese etc Therefore if you observe improper operation of the device please take control measurements with another electrode or check the used electrode with another pH meter Generally the deterioration of the meter work is caused by the electrode and not by the meter In case of conductivity measurements it is important to choose the cell with right constant K value for the measuring range Wrong selection may cause larger error occur similar situation occurs during measurements with automatic temperature compensation with incorrectly introduced a coefficient Accuracy of the dissolved oxygen measurements depends on the sensor calibration and regular maintenance which consist in replacing the membranes electrolyte and cleaning the electrodes Lack of correct maintaining of the sensor after some time will make measurements impossible Please turn your attention to the fact that stabile m
46. l be displayed Using w or buttons choose La low resolution of the measurement 0 01 pH i high resolution of the measurement 0 001 pH b Choose the electrode number under which the parameters of calibration will be stored Press the button than using or buttons choose the electrode number symbols t i Etc ELJ under this number the calibration results will be stored Above the electrode number following signs will be displayed Lic under this number there is no characteristic stored and producers values are provided 5ft under this number there are values of last calibration stored b o the last calibration showed that the electrode is loosing it s efficiency and in short time it s calibration won t be possible c Choose or block the function of automatic correction of the change of pH value of buffer solution with the temperature To do so one should press the button than a FLAL symbol points of calibration will be displayed pic 5 next using or buttons choose 22 Fut automatic change of the stored pH value of the buffer solution by it s temperature change according to table 3 uSt setting the value of the buffer solution in the range given in table 3 rir en M LIIL F H uE cond mV O time Pic 5 After choosing the fut symbol one should press the button and start the calibration in buffer solutions according to point e and chapter 8 4 After choosing the U St act ac
47. lutions is stored This dependence is showed in the table 3 Those values are taken into consideration when the calibration is done in other temperatures Values between the points are approximated linearly The highest accuracy may be obtained only when the pH values of the buffer solutions are identical as in the table If there are some differences between the values given in the table and values given by the producer of buffer solutions one should judge weather the error which will occur during calibration with automatic correction of the value won t be to big If yes one should resign from using this option The range of the temperatures taken into consideration during introducing the correction is 0 to 60 C and can t be exceeded 20 Table 3 Kind of buffer solution w C oxalate phthalate phosphate di sodium calcium tetraborate hydroxide 1 666 4 003 6 984 9 464 13 423 1 668 3 999 6 951 9 395 13 207 1 672 oa 1 675 4 002 6 881 9 225 12 627 1 679 4 024 60 1 723 4 091 6 836 8 962 11 449 Ria R EE A ol oj o ajo 21 8 3 The actions during calibration One should a Choose the resolution with which the buffer solution value will be introduced Depending on the fact weather the buffer solutions have the pH value given with 2 or 3 decimal places one should choose the right resolution Using button choose the pH function next press the button art resolution sign wil
48. maintenance Calibration 15 1 Calibration without the sample solution 15 2 Calibration with use of sample solution The simplified way of determining the a coefficient Entering the a coefficient value The conductivity measurement 18 1 The measurement without temperature compensation 18 2 The measurement with temperature compensation 18 3 The measurement with manual temperature compensation NOOK 10 11 12 14 15 17 19 21 24 26 26 26 27 27 28 29 22 19 Salinity and TDS measurement 46 19 1 Salinity measurement with conversion to NaCl or KCI content 47 19 2 Determining the Wrps coefficient 48 19 3 The measurement of salinity with conversion to TDS 48 IV Oxygen concentration measurement 20 Basic information about dissolved oxygen measurement 50 21 The oxygen sensor 52 22 Entering the parameters 52 22 1 Changing the number of probe 52 22 2 Changing the unit 53 22 3 Salinity influence compensation 53 22 4 Automatic compens of the atmospheric pressure influence 56 23 Calibration of the oxygen probe 57 24 Oxygen concentration measurement 59 24 1 Measurement with automatic temperature compensation 60 24 2 Measurement with manual temperature compensation 60 V Atmospheric pressure measurement 25 Atmospheric pressure measurement 62 VI ORP mV and temperature measurement 26 ORP voltage measurement 64 27 Temperature measurement 64 Vil Other 28 Clock date auto switch off function 66
49. mmerse the cell in distilled water with washing up liquid and than wash it in distilled water 46 19 SALINITY AND TDS MEASUREMENT Salts and minerals dissolved in natural water influence the conductivity which in principle is proportional to the quantity of dissolved substances This dependence enables after some calculations to determine the salinity of the measured solution in concentration units g l or or determine the TDS Total Dissolved Solids The received values are always approximated and the final accuracy depends on the way of making the calculations concentration of the measured solution and it s temperature In most salinity meters a simplification is used that dependence between the conductivity and salinity in the solution is linear in the whole measuring range Usually a 0 5 coefficient is used the conductivity result in mS cm is multiplied by this coefficient and the result of salinity in g l is received ex if the conductivity value is 2 mS cm the salinity is 1g l In reality the dependence between the conductivity and salinity isn t linear the conversion coefficient is changing together with the concentration and temperature The table 6 shows the dependence between conductivity and real salinity of NaCl solution in temperature 25 C and values of salinity counted for constant coefficient 0 5 This comparison shows that for greater concentrations using the constant coefficient introduces large error Table 6
50. mpensating the temperature influence on the membrane Because of the limited accuracy of this compensation the highest accuracy can be achieved by calibrating the sensor at the same temperature at which the measurement will be carried out The measurement error increases with the increase of the difference between the calibration and measurement temperatures and results from characteristic features of the sensor but not from the device For the applied sensor ELSENT this error is about lt 3 at a 5 C temperature difference and increases to 5 at a 10 C temperature difference If a higher accuracy is required the interval from the last calibration must be additionally taken into consideration signal drift If the salinity of the tested solution is very small the measurement can be started without entering it s value value 0 00 g l should be entered However accurate measurements should be preceded by the determination of the salt content in the tested solution The salinity of the solution can be determined simply by measuring the electric conductivity using the conductivity meter The easiest way to determine the salinity is conductivity measurement with conversion to NaCl The salinity value is introduced according to chapter 22 3 60 24 1 Measurement with automatic temperature compensation To make the measurement with automatic temperature compensation one should connect the temperature probe with the meter insert t
51. n solution OXYGEN METER ae 400 0 Of probe 1 digit 0 60 00 mg l 0 01 mg l Of probe 1 digit TEMPERATURE COMPENSATION RANGE 0 0 40 0 C SALINITY COMPENSATION RANGE 0 0 50 0 g l Atmospheric pressure compensation range 800 1100 hPa Probe calibration Two point One point Oxygen probe 0 and 100 Oz in 100 02 membrane galvanic Accuracy given in the oxygen Probe section page 52 77 ATMOSPHERIC PRESSURE MEASUREMENT Accuracy 1 digit 800 1100 hPa Atmospheric pressure sensor NPP 301 TEMPERATURE MEASUREMENT z Accuracy 50 0 199 9 OC accuracy of the meter Final accuracy of the measurement depends on the accuracy of the used PT 1000 probe TEMPERATURE PROBE platinum resistor Pt 1000 ACCURACY OF THE PROBE IN RANGE 0 100 C FOR PT1000B RESISTOR 0 8 C FOR PT1000 3B RESISTOR 0 27 C OTHER WORKING TEMPERATURE 5 45 0C POWER 1 9V battery type 6F22 2 stabilised power adapter 9V POWER CONSUMPTION 60 mW SCREEN Custom LCD 55 x 45 mm DIMENSIONS 149 x 82 x 22 mm WEIGHT 222 g with battery 78 34 EQUIPMENT The standard equipment for the CX 400 meter is 1 2 3 Temperature probe Pt 1000B standard Plastic container for the meter electrode and temperature probe Users manual with warranty The additional equipment available for this meter is NOORWN 8 9 Conductivity cells for different conductivity ran
52. nt ways of action 1 enter the value of pH buffer solutions depending on the actually used buffers in the range given for each point of calibration 2 use the values of pH sample solutions entered to the memory by the manufacturer Those values are in conformity with the NIST norm This type of calibration switches on the automatic correction introduction connected with the change of sample solution along with temperature changes Choosing the second option makes the calibration much easier The user doesn t need to warm up or cool down the sample solutions to the temperature given by the user This option includes some simplifications and when very high accuracy is required it shouldn t be used The meter stores independently 5 values of the buffers for each of the calibration modes described above 8 1 Introducing the pH values of buffer solutions Values of the buffer solutions set by the producer in the meter s memory are given in the table 1 Point of Resolution Resolution Calibration 0 001 0 01 Table 1 If the values of used buffer solutions are different than the given above the user may change the set values 18 Range of possible changes is given in the table 2 There is possibility to introduce the values of buffer solutions with two or three decimal places The meter doesn t allow for introducing pH values in ranges other than those given in the table 2 Table 2 3 F600 709 C _ 8 900 A 11 5
53. one point calibration should be done with buffer solution close to 7 00 pH Thanks this the so called zero electrode shift will be eliminated In other points a standard characteristic will be taken from the meter s memory This characteristic corresponds with theoretical efficiency of the pH electrode If measurements are done both in acids and alkalis and the measurements are not done at the ends of measuring range it is enough to calibrate the electrodes in 3 buffer solutions with values in range given in table 2 calibration points 2 3 and 4 In case of accurate measurements in the whole range it is recommended to calibrate the electrode in all 5 points given in the table IN CX 401 characteristic of the electrodes is approximated linearly between the calibration points Starting the calibration under one of the electrode numbers does not remove the set buffer values but irreparably removes the electrode characteristic stored under this number There is no possibility of calibrating only one point leaving the rest of data from the last calibration CX 401 enables independent storing of 3 characteristics of pH electrodes This feature is especially useful when fast replacing of the electrodes is necessary or when it was broken Those electrodes should be earlier calibrated and brought into memory under following symbols t i Etg ELI 17 The order of using the buffer solutions is freely chosen The user may choose two independe
54. ower row on LCD a wnt unit symbol with buttons choose in the upper row on LCD sign ang measurement in units of conductivity pic 9 O Pic 9 34 unie measurement result counted to NaCl in g l pic 10 O time Pic 11 LJL rca measurement result counted to TDS in g l pic 12 Pic 12 35 In case of salinity measurement AEL FEL or tc 5 short pressing of the button chooses displaying the result in of weight concentration or g l By the symbol with name of the salt a or g l symbol will be displayed by pressing the enter the measuring mode The result of measurement in of weight concentration may be counted to value in ppm according to dependence 1 of weight concentration C 10 000 ppm 10 ppt Resolution of measurement in of weight concentration is 0 001 or 10 ppm 13 2 Entering the Wrps coefficient In case of measurement of salinity with conversion to TDS it is necessary to introduce the Wrps coefficient One should follow the steps in the conductivity measuring mode few times press the button till moment of displaying in the upper row on LCD acca symbol TDS coefficient pic 13 with buttons enter the correct value of the TDS coefficient enter the measuring mode by pressing the button O Pic 13 The way of determining the Wrps coefficient is described in section 18 2 36 14 CHOICE AND MAINTENACE OF THE CONDUCTIVI
55. p button 25 In this moment the result will blink what will inform about storing the calibration result in this same time in the upper row the corrected value of measurement will be displayed it will be equal the value of used buffer solution pic 8 If the function of automatic correction of the temperature influence on pH value of the buffer solution is used this value will be considered in the displayed value of the buffer solution If by accident someone will use buffer solution different than those set for the calibration the meter won t be able to detect this value and Err sign will be displayed In this case it is necessary to check the value of the buffer solution or the electrode which may be broken or clogged cag loH LILI I 307 CAL C LILI cond mV O time Pic 8 c one may finish the calibration at this moment by pressing the button or continue the calibration in other buffer solutions by washing the electrode and temperature probe before every immersing in the buffer and acting according to the point b After calibrating one electrode it is possible to calibrate two others choosing the two remaining symbols according to point 8 3 b If after choosing the electrode number and entering the calibration mode one will exit without making the calibration the earlier stored characteristic will be deleted and a standard characteristic will be adapted 26 8 5 Calibration with manual temperature comp
56. pensation which is connected with change of the electrode efficiency and not with the change of the measured solution caused by temperature change Changes of the pH values of some solutions with the temperature are very small and others big ex pure water When comparing solutions which change their values together with the temperature change it should be done in this same temperature Sometimes it happens that results of measurement in this same solution in stable temperature are different When analysing such a situation it is important to take following factors into consideration differences may occur because of poor quality electrode The result was treated as stabilised to fast medium class electrode needs about 40 seconds to full stabilisation the measured solution may not be homogeneous and lack of magnetic stirrer doesn t allow for obtaining similar results During measurements in sewage some chemical reactions which change the result may occur Very small differences may be caused by the meters accuracy The CX 401 accuracy is 0 002 pH 1 digit what practically means that in extreme situation results of 2 measurements may differ for 0 005pH and this will be an acceptable error because 1 measurement will be made with 0 002 pH error and second with 0 002 pH 1 digit information explains difference caused by rounding up of the result on the last visible place on LCD discretisation error 30 If after making a t
57. ple solutions The calibration is done in the actually chosen unit subchapter 13 1 15 2 1 Entering the value of sample solution To enter the value of sample solution one should choose the unit according to point 12 1 in the conductivity measuring mode press the button till appearing a CAL symbol in the lower row on LCD pic 16 with buttons enter in the upper row on LCD the value of sample solution enter the measuring mode by pressing the button Pic 16 15 2 2 Calibration with automatic temperature compensation What to do enter the value of sample solution point 15 2 1 connect the conductivity cell and temperature probe immerse both probes in the sample solution hold the conductivity cell at least 1 cm away from the bottom and walls of the vessel The measuring cell should be completely filled with the measured solution there shouldn t be any air bubbles and the electrodes should be evenly moistened measure the temperature of solution and bring it to 25 C press and hold the button till appearing a CAL symbol on the display pic 17 air bubbles may be removed by moving the immersed cell To make the moistening of the electrodes easier it is recommended to immerse the cell in distilled water with washing up liquid and than wash it in distilled water 40 wait till the stabilisation of the value and press the button Pulsating of the results informs about storing in the
58. r 42 5 Enter with the keyboard temperature value 25 C 6 Again measure the conductivity of the solution ex in 20 C This value will be different than in 25 C Gtx 7 Determine the a coefficient using the formula a Gos Grx Gos 25 Tx x 100 C where T value of the changed temperature in C Ges conductivity measured in 25 C Gtx conductivity measured in temperature Tx This same should be done reducing the temperature to ex 15 10 and 5 C taking down the counted values of a coefficient This same may be done raising the temperature of the sample During measurements in temperatures different than 25 C before starting measurement it is necessary to introduce the received a coefficient for the existing temperature 17 ENTERING THE a COEFFICIENT VALUE The a coefficient range in CX 401 is 0 10 00 with accuracy of regulation 0 01 C For the measurements it is possible to adopt the most often used temperature coefficient a 2 C or in case of higher accuracy requirements determine the kind of measured solution and choose for it the correct value of this coefficient To introduce the a coefficient one should in the conductivity measuring mode press the button till displaying the screen with value of the a coefficient pic 18 A teat temperature coefficient a symbol will be displayed with buttons enter the value of the coefficient return to the m
59. rode redox electrode or the dissolved oxygen sensor to BNC 50 input F1 join the conductivity cell in case of using the temperature probe it should be connected with the chinch temperature input t In case of printing or work with PC join the interface El 401 or cable CP 4XX PC with RS input switch the meter on by pressing the button CAUTION during pH measurements the conductivity cell has to be disconnected from the meter or removed from the measured solution in which the pH electrode is immersed 6 1 Choosing the kind of temperature compensation The meter switches it self to the automatic temperature compensation mode automatically after joining the temperature probe after disconnecting it the meter enters the manual temperature compensation mode In ATC mode near the displayed temperature a 6 symbol appears Manual temperature compensation is indicated by Y symbol near the value entered by the user it may be changed using or keys 12 6 2 Changing the resolution of the measurements The measurement results may be displayed with chosen resolution To change it one should in the measuring mode press the button ar 5 resolution sign will be displayed Pic 4 Using keys or one may choose La low resolution of the measurement h high resolution of the measurement cond mV time Pic 4 For the pH measurement La resolution of the measurement 0 01 pH h resolution of the me
60. sed cell To make the moistening of the electrodes easier it is recommended to immerse the cell in distilled water with washing up liquid and than wash it in distilled water A1 16 THE SIMPLIFIED WAY OF DETERMINING THE o COEFFICIENT The knowledge of a coefficient has a crucial significance during measurements in temperatures different than 25 C This coefficient is changing together with the temperature and concentration Below we are giving values of a coefficient in 25 C for few compounds with determined weight concentration Table 4 Weight a Concentr coefficient In the table 5 there are rough values of a coefficient for KCI and NaCl depending on the temperature and concentration of the measured liquid Table 5 a coefficient SHa KCI solution Saturat ed NaCl In practice the a coefficient may be determined with simplification that on the value of this coefficient greater influence has the temperature change than changes in the composition of the salts and their concentration what shows the data in table 5 To determine the coefficient one should 1 Take the solution which conductivity will be measured in temperatures different than 25 C 2 Bring the solution in the lab to 25 C and measure it s conductivity G25 3 Change the temperature to other determined value ex 20 C 4 Turn the meter to manual temperature compensation by disconnecting the temperature probe from the mete
61. ter measurements The conductivity probe maintenance mainly consists of accurate washing the inside of the measuring cell with distilled water It is forbidden to clean the platinum electrodes mechanically because the platinum layer may be rub of what will result in decreasing the accuracy may cause lowering the stability and change the constant K Measurements of liquids with oils and heavy sediments content may cause platinum contamination make the measurement impossible and irreparably damage the electrodes In case of fat content in the measured liquids it is possible to clean the electrodes by immersing the cell in acetone chloroform fourhydrofuran or detergent Some norms propose universal liquid for cleaning the cells This is mixture of equal parts of isopropyl alcohol ethyl ether and hydrocholic acid diluted with water in 1 1 ratio The conductivity probe with broken measuring cell can t be used for further measurements because the constant K is greatly changed the result is unstable and the influence of placing the cell in measuring vessel greatly changes the result 38 15 CALIBRATION The calibration is done to prepare the meter for cooperation with the used conductivity probe this is the essential condition for obtaining accurate results The calibration may be done without the sample solution by entering to the meter s memory known value of the constant K of cell or with use of standard solution with known cond
62. the interval isn t necessary c Prt printing yes or no With buttons one has to choose an when the results should be printed or af when they should be stored in the memory d ALi Way of displaying the stored results an successively number of sample result time and date of storing the result aFF successively number of sample and result Changing with buttons Return to the results readout display after pressing button Exit from the readout mode after pressing of the button 70 29 3 Storing the single measurements in the memory If according to previous section storing of single results was chosen every pressing of button stores the measured result The results are stored as the next ones after the last stored If someone was checking the earlier stored results and didn t return to the last one the results won t be deleted and the value will be stored after the last measurement If the user wants to store the result from the chosen number first he has to delete the results as described in the point 29 6 and next start storing the results by pressing the button During storing the results the number of result will be displayed for a moment If after pressing the button instead of number an End sign will be displayed it informs that the maximal number of results was stored 29 4 Storing the measuring series There is possibility to store series of measurements up to 200 measurements To do so
63. the test was successful after about 1 5s the meter switches it self automatically to the measuring mode in which it was switched off If a HELP sign will be displayed it means that the meter has lost the factory settings and requires the service repair If after the 1 5 s all symbols will be continuously displayed it informs that the calibration parameters of electrodes or cells were lost After pressing the button the meter will take standard characteristics shift 0 pH characteristic slope 100 for pH electrode constant K 1 000 cm for conductivity cell shift 0 Oz characteristic slope 100 Oz for oxygen sensor And will enter the measuring mode It will be necessary to calibrate the conductivity cell pH and oxygen electrodes The meter is switched off by pressing and longer holding of the button till displaying of the aff symbol In case of working on the batteries to save them the meter switches it self automatically off after the time set by the user from last pressing of any button Way of introducing the time is described in the paragraph number 21 This function is switched off for the time of calibration taking the series of measurements printing the memory content and work with the power adapter 11 6 PREPARATION TO WORK Before starting the work one should join the power adapter plug to the P input if work with the power adapter is planned to BNC 50 input F join the ready to work combination pH elect
64. to the end of memory will be printed in case of setting the 5 parameter to ofF only the result stored under the chosen number will be printed In case of setting the i parameter to an together with the result of measured function and temperature the hour and date will be printed 31 POWER SOURCE AND CHANGING THE BATTERY The meter is 9V battery or stabilised power adapter powered The adapter should be joined with the P connector pic 2 The battery is necessary to keep the clock going Joining the power adapter disconnects the battery The battery condition may be checked according to chapter 28 4 Displaying the symbol informs that the battery should be changed To do this it is necessary to unscrew the two screws in the lower wall of the meter pull out the whole wall and replace the battery The next thing is to put the battery back into the meter and mount the wall The special shape of the wall disables wrong mounting only in one position it is possible to put the wall on The wall on the edge has a sealing ring It is very important to pay attention during closing the meter if the ring on the whole edge was put inside the housing If it is correct screw the screws till feeling the resistance not to hard Leaving the wall not correctly screwed causes loosing the waterproofnes and may cause that water will get into the meter and will destroy it This kind of failure is not repaired on the warranty conditions 74 32 CO OPERATI
65. uctivity Constant K of the conductivity cell may change as reaction to contamination of the electrodes that s why periodically it is necessary to check the meters indications on the sample solution and eventually repeat the calibration When using three cells it is possible to store their characteristics under the Pr Pre Pr3 symbols 15 1 Calibration without the sample solution The meter has the possibility of calibration without the use of sample solution To make this calibration it is necessary to know the constant K of the conductivity probe This value may be given by the cell producer or may be determined using the CX 401 meter after making the calibration in the sample solution To make the calibration one should in the measuring mode press the button till displaying the screen with the value of constant K pic 15 with buttons symbols Pr Pz Pr 3 choose the number of cell press the button on the display a CAL symbol will be displayed with 2 buttons enter the value of constant K press the button and return to the mode of choosing the number of cell or enter the measuring mode by pressing the button Pic 15 39 15 2 Calibration with use of sample solution The meter enables one point calibration in the freely chosen sample solution To decrease the error it is recommended to use solutions with value close to the forecasted value of measurement It is required to use high quality sam
66. vity measurement it is possible to determine the Total Dissolved Solids It is assumed that the salt s composition in the taken samples is not changing significantly 19 1 Salinity measurement with conversion to NaCl or KCI content The measurement of salinity with conversion to NaCl or KCI content should be done as follows choose the salinity measurement with conversion to NaCl or KCI content according to chapter 13 1 choose the unit g l or then act as during the conductivity measurement chapter 18 after stabilisation read the result 48 19 2 Determining the Wps coefficient For salinity measurement with conversion to TDS content it is necessary to determine the Wrps coefficient and enter it to the meter s memory To do so it is necessary to make the conductivity measurement of the tested water with exactly given volume or weight In traditional way determine the Total Dissolved Solids in this water and than count the coefficient according to the below given formulas 1 If the result is to be displayed in g l Wrps TDS lv where Wrps TDS coefficient TDS Total Dissolved Solids in g l y conductivity of the sample in mS cm Caution the TDS value should be counted to volume of sample equal to 1l 2 If the result is to be displayed in of weight concentration Wrps TDS lv where Wrps TDS coefficient TDS Total Dissolved Solids in g kg y conductivity of the sample in mS cm Caution t
67. will the result change when the temperature will change for 1 C The a coefficient in this meter may be changed in range 0 10 00 C The value of this coefficient is introduced to the memory by the user For NaCl in temperatures close to 25 C it is 2 C Ex in case of measurements in 30 C the result changes 5 x 2 10 The counting is done automatically and takes the introduced by the user value of the a coefficient into consideration The value of this coefficient may be found in the literature or may be approximated by the user 33 The conductivity despite the electronic precision should always be treated as burdened with some error which depends on the error of conductivity cell it s linearity temperature and first of all depending on the a coefficient during measurements in temperatures different than 25 C 13 PREPARATION TO WORK Before the calibration and measurements it is necessary to make all activities described in the chapter 6 Additionally according to the chapter below it is necessary to choose the unit in which we will make the calibration and measurement 13 1 Choosing the unit The result of the measurement may be displayed in units of conductivity and salinity The salinity may be counted to NaCl KCI or TDS content The result may be displayed in of weight concentration or in g l To choose the unit one has to in the conductivity measuring mode press the button till displaying in the l
68. with possibility of changing their value option of automatic introduction of temperature correction on the value of pH buffer solutions NIST norm information about the condition of the pH electrode storing of three characteristics of electrodes in each function wide range of conductivity measurement with 6 automatically switched subranges autorange counting the conductivity to salinity in NaCl or KCI according to real dependence to conductivity possibility of introducing the TDS coefficient Calibration of the conductivity cell by introducing the constant K or on sample solutions function of determining the constant K of cell automatic compensation of the salinity influence on the oxygen measurement using the conductivity measurement function measurement and automatic compensation of the atmospheric pressure influence on the dissolved oxygen concentration internal datalogger for 200 measurements with time date and temperature taking series of measurements with set time interval RS 232 output possibility of printing the measurement results or values stored in the memory on standard printer with use of interface Information about the battery condition automatic switch off function after time set by the user 6 3 WHAT IS THE METER DESIGNED FOR Waterproof multifunction meter CX 401 is precise and easy to use meter designed for hydrogen ion concentration measurements in pH units Ox
69. wo point calibration in pH buffers 7 00 pH and 4 00 pH acidic conditions the results are checked in 9 00 pH alkali conditions in some cases the result may be 8 90 pH or 9 10 pH This may occur when the electrode has unsymmetrical characteristic Making a 3 point calibration with alkali neutral and acidic buffers may prevent from such errors Sometimes the measurement results are unstable the quality of the electrode has the crucial influence In most cases the reason for slow drifting of the result it s unstability or prolonging the time of stabilisation is the clogged junction broken electrode or contaminated membrane Often it happens when wrong kind of electrode was chosen for the kind of measured solution Leaving the electrode for few hours in the distilled water or placing it in water with detergent may eliminate this symptoms especially if the measurements were done in solutions with deposits fats or oils The electrode which for a long time wasn t used may have the junction clogged by KCI crystals what may be removed by placing the electrode in distilled water Heavily contaminated electrode may be cleaned in chloroform and deposits of iron in 2N HCl The electrode life may be prolonged by storing it in KCI solution Depending on the kind of measured solution or substance proper kind of electrode should be chosen They differ one from another with shape membranes look kind of junction and body Electrodes for heavily polluted sew
70. y This function is also switched off for the time of calibration time of making a series of measurements printing the memory content and work with power adapter 67 28 4 Checking the battery condition Disconnect the power adapter enter the time function and press the button till moment of displaying in the upper row a htt symbol pic 29 In the lower row the condition of battery described in will be displayed 100 the battery is full 0 the battery should be replaced In case of using the power adapter instead of the sftt symbol a SUF symbol will be displayed and value 100 bAtE l 19 cond pH mv Pic 29 Pressing the button returns the meter to the time mode 28 5 Setting the time and date The setting mode of the actually displayed parameter one enters by pressing and holding the button The position which we are going to change starts blinking the value is changed with or buttons The pulsating position is chosen by short pressing of the button After pressing the button the setting mode is being left 68 29 STORAGE AND READOUT OF THE RESULTS 29 1 Storing or printing The meter enables storing readout or printing of 200 results of actually measured function The results are stored in EEPROM memory which is non volatile so the data isn t lost even after complete lack of power There is also possibility to printout on request the result of measurement which is being done at this mom

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