User`s Manual - Turner Designs
Contents
1. PSU Positive Connection 1 Red Signal Output White Figure 1 Analog Ground Green With the C sense connected as shown in Figure 1 answer the following questions to verify the sensor is functional 1 Isthere voltage output The C sense has a 45 second warm up period during which the output values will be zero or near zero After 45 seconds the output voltage should be at a level that corresponds to at least 400 ppm This voltage can be calculated using the equation on your C sense calibration sheet For instance if the eguation on your calibration sheet is y 806 85x 42 403 where y is the concentration of COo in ppm and x is the voltage from the C sense in volts set the concentration to 400 ppm and solve for x 998 2410 Rev C Page 6 x 400 42 403 806 85 0 5483 Therefore this C sense sensor should output 0 5483 volts when the pCO gt concentration is 400 ppm 2 Does the voltage output change To cause a change in the output voltage breathe across the membrane for at least one second Human breath contains 40 000 50 000 ppm of CO therefore this should result in a significant increase in output voltage Note Moving the sensor in air may not result in any change 998 2410 Rev C Page 7 3 Maintenance 3 1 Gas Transfer Interface The only component of the C sense requiring maintenance is the gas transfer interface a semi permeable hydrophobic membrane Th2. 60 a v 50 a s 40 sg 30 E 20 8 S 10 g 0 0 10 20 30 40 Water Temperature degree C 998 2410 Rev C Page 17 Example PCO measured 1000 ppm Calibration pressure 1000 mbar Atmospheric pressure 1000 mbar Temperature of water 20 C If the sensor was measuring CO in the air there would be no correction needed for pressure as the calibration pressure and atmospheric pressure are the same In water however the TDGP is greater than atmospheric pressure due to the added partial pressure of H20 From the previous figure at 20 C an additional 20 mbar of gas pressure will be present in the water and sensor gas head space This eguals a TDGP of 1020 mbar Using the following equation where pCOzcor is corrected PCO and pCOzmea is the value measured by the C sense pCOcor pCO mea calibration pressure 1000 ppm 1000 mbar TDGP 1020 mbar pCO cor 980 4 ppm Corrected pCOz 980 ppm 998 2410 Rev C Page 18 Appendix F Conversion of Common CO Units Gaseous COzis commonly measured in units of parts per million ppm This is the ratio of the number of CO molecules per million molecules of air The ppm of CO in air does not change with pressure The ppm CO is also referred to as the mixing ratio xCOo In natural waters CO g is often reported as a partial pressure pCOo with units of microatmospheres atm Unlike xCOz PCO is dependent on the total dissolved gas pressure The tw
3. where to return the end of life product If you purchased your instrument directly from Turner Designs please contact Turner Designs Customer Service By Phone 1 408 212 4041 or Toll Free 877 316 8049 By Email Customer Service at support turnerdesigns com Turner Designs will provide aWEEE RMA Number a Shipping Account Number and a Ship to Address Package and ship the product back to Turner Designs The product will be dealt with per Turner Designs end of life recycling program in an environmentally friendly way 998 2410 Rev C Page 3 1 Introduction C sense is a compact lightweight plug n play sensor designed for measurement of the partial pressure of CO gas in liquids Combining an oil resistant hydrophobic membrane and a temperature compensated non dispersive infrared NDIR detector C sense measures the partial pressure of COzin water oil and water and oil mixtures C sense operates through the diffusion of gas across a hydrophobic membrane into an isolated headspace While any resident gas may enter the headspace the wavelength of the infrared sensor is specific to CO2 absorption The amount of absorption of that wavelength is proportional to the concentration of CO2 gas in the headspace C sense automatically compensates for changes in temperature however the effects of water vapor and variable total dissolved gas pressure TDGP can be significant and should be considered TDGP is the total pressure exhibite
4. CO cor pCOzmea calibration pressure TDGP Or pCOszcor PCOzmea calibration pressure TDGP 998 2410 Rev C Page 16 Appendix E Effects of Water Vapor on Measuring pCO gt 2 C sense employs a semi permeable membrane to eguilibrate a gas head space within the sensor with surrounding water All gases dissolved in the water transfer across the membrane into the head space including water vapor The amount of water vapor in air is commonly referred to as humidity For a sensor submerged in water the relative humidity of an equilibrated gas head space is approximately 100 Measurement of PCO in this condition of 100 humidity is called a wet measurement There are two effects of water vapor on the pCO reading of the sensor elevated total dissolved gas pressure TDGP and a phenomenon called pressure broadening of absorbance lines The broadening of spectral absorbance lines is a minor effect of water vapor on the absorbance of CO at low CO levels and at low temperatures For example the error in pCOz for a 1000 ppm sample at 30 C is on the order of 4 6 ppm At half this temperature the error drops to 2 3 ppm The more significant error due to water vapor is the contribution to TDGP The figure below shows the total partial pressure exerted by water vapor as a function of temperature of the water As water temperature increases the partial pressure of H20 increases in a non linear fashion 80 70 5
5. TURNER DESIGNS SENSE in situ PCO gt Sensor User s Manual April 30 2015 P N 998 2410 Revision C TURNER DESIGNS 845 W Maude Avenue Sunnyvale CA 94085 Phone 408 749 0994 FAX 408 749 0998 Table of Contents 1 Introduction 2 Instrument Setup 2 1 Instrument Checklist 2 2 Optional Accessories 2 3 Gas Concentration Ranges Available 2 4 Deployment 2 5 Functional Test for C sense 3 Maintenance 3 1 Gas Transfer Interface 3 2 Cleaning the Interface 4 Troubleshooting 5 Warranty Appendices A Sensor Specifications B Wiring Guide C Calculating pCO2 from C sense Voltage Output D Correcting for High TDGP E Effects of Water Vapor on Measuring pCOz F Conversion of Common CO Units G Logging Options for the C sense 998 2410 Rev C 01 01 OI 01 00 00 Page 2 WASTE ELECTRICAL AND ELECTRONIC EQUIPMENT WEEE DIRECTIVE Turner Designs is in the business of designing and selling products that benefit the well being of our environment Accordingly we are concerned with preserving the surroundings wherever our instruments are used and happy to work with customers by complying with the WEEE Directive to reduce the environmental impact resulting from the use of our products WEEE Return Process To arrange the return of an end of life product proceed as follows If you purchased your instrument through a Turner Designs Distributor please contact your local representative They will instruct you
6. ble with locking sleeve P N 105 2412 25 meter pigtail cable with locking sleeve P N 105 2413 50 meter pigtail cable with locking sleeve P N 105 2414 e Water Pumped Head P N 2400 700 I Vi 2 3 Gas Concentration Ranges Available 0 1000 ppm P N 2400 001 0 2000 ppm P N 2400 002 0 4000 ppm P N 2400 004 Other C sense ranges available by special order 2 4 Deployment Turner Designs recommends the sensor be deployed horizontally in order to reduce or eliminate particulates in the water column from settling on the semi permeable membrane and to release gas bubbles trapped or formed on the membrane surface An alternative solution to these potential sources of error is the use of the Water Pumped Head PN 2400 700 The shear forces generated by pumping water past the membrane will prevent settling of particulates as well as force bubbles out of the sample volume In addition the Water Pumped Head has the advantage of decreasing equilibration times 998 2410 Rev C Page 5 2 5 Functional Test for C sense To perform a functional check on the C sense connect the colored wires from the pigtail to the power supply and multi meter as shown in Figure 1 below Additional Equipment required for functional tests DC Power Supply 6 12 VDC gt 100 mA Multi meter to read 0 5 VDC lt gt Note Supply voltages greater than 13 5 VDC will result in damage to the sensor DC Power Supply Multimeter Supply Ground 0 VDC Black
7. ced persons during the deployment and recovery of their instruments and cannot be held liable for any injuries or damages incurred during use of their instruments 5 2 Warranty Service To obtain service during the warranty period the owner shall take the following steps 1 Write email or call Turner Designs Technical Support and describe as precisely as possible the nature of the problem Phone 1 877 316 8049 Email support turnerdesigns com 2 Carry out any adjustments or tests as suggested by Technical Support 998 2410 Rev C Page 10 3 If proper performance is not obtained you will be issued a Return Materials Authorization number RMA to reference Package the unit write the RMA number on the outside of the shipping carton and ship the instrument prepaid to Turner Designs If the failure is covered under the warranty terms the instrument will be repaired and returned free of charge for all customers in the contiguous continental United States For customers outside of the contiguous continental United States who purchased eguipment from one of our authorized distributors contact the distributor If you purchased directly contact us We will repair the instrument at no charge Customer pays for shipping duties and documentation to Turner Designs Turner Designs pays for return shipment custom duties taxes and fees are the responsibility of the customer 5 4 Out of Warranty Service Follow steps for Warranty Serv
8. d by all gasses within the water column When this pressure greatly exceeds the pressure at which the C sense was calibrated the output of the C sense should be corrected This correction is outlined in Appendix D Correcting for High TDGP Water vapor absorbs at the same wavelength as CO and therefore the presence of water vapor in the headspace can cause an overestimation of the CO2 concentration This effect can t be corrected for without measuring relative humidity within the headspace For a discussion of how water vapor affects the operation of the C sense see Appendix E Effects of Water Vapor on Measuring pCO Operation of C sense reguires supplying 6 12 VDC and recording an output of 0 5 VDC The output of the sensor is directly proportional to the concentration of pCOo In order to obtain quality measurements a user needs to understand the effects of the equilibration time and warm up time of the NDIR detector in the context of the intended sampling protocol 998 2410 Rev C Page 4 2 Instrument Setup 2 1 Instrument Checklist Each sensor purchase comes complete with e C sense Analog Sensor with a 4 pin Impulse connector MCBH WB 4 MP SS e Copper tape cut outs 30 ea P N 2400 506 3 e USB drive with documentation 2 2 Optional Accessories e Pigtail Cables with Locking Sleeve 0 6 meter pigtail cable with locking sleeve P N 105 2410 5 meter pigtail cable with locking sleeve P N 105 2411 10 meter pigtail ca
9. e membrane assembly is extremely sensitive and should never be disassembled or touched The membrane and sensor face are engineered to minimize biofouling however under most conditions biofilms will slowly form on the surface of the membrane resulting in e Anincrease in equilibration time due to decreased permeability of the membrane e Reduced accuracy of CO estimates due to production of CO2 by organisms contained within the biofilm Care should be taken to ensure that the interface is not damaged through scratching or extreme gas overpressure Small surface scratches on the interface can result in sudden failure and flooding of the instrument under large pressures either hydrostatic or dissolved gas pressure The outlined procedure for cleaning the interface section 3 2 should be strictly adhered to In environments where total dissolved gas pressure TDGP is substantially above atmospheric pressure caution is reguired when removing the sensor from water As water pressure compresses the membrane against a pressure plate when submerged any gas pressure buildup on the reverse side of the membrane can result in bulging of the membrane when removed from immersion In cases of high TDGP it is recommended to slowly bring the sensor to the surface while monitoring gas pressure The excess gas pressure will slowly dissipate as the sensor approaches waters in equilibrium with the atmosphere In addition high TDGP causes significant error in
10. gative 0 VDC Connection C sense Connector Pins C sense Cable Holes Figure AB1 Pinout diagram from the back of the C sense The connector is a 4 pin Impulse male MCBH WB 4 MP SS 998 2410 Rev C Page 14 Appendix C Calculating pCO from C sense Voltage Output Below is a calibration sheet with the eguation to convert voltage output from a 0 4000 ppm C sense into PCO concentration in ppm The slope and offset in this equation are determined at the factory and are specific to C sense serial number 2400110 Be sure to use the slope and offset specific to your sensor when making this calculation Te TURNER SpR W ee il DESIGNS 2 Reliable Instruments for an Unreliable World DNV C sense Serial 2400110 Calibration curve Calibrated on February 20 2014 at 100 7 kPa pressure S N 2400110 _ 4000 4 97 4000 E A Es A 3000 g Fr S Pod 2000 2 608 2000 o 1000 5 ett y 806 85x 42 403 0 16 0 0 1 2 3 4 5 Sensor output V In the equation above y is the concentration of CO in ppm and x is the voltage coming from the C sense Using the 2 points defined on the graph at 2 608 VDC and 4 97 VDC as an example y 806 85 2 608 42 403 2061 9 ppm y 806 85 4 97 42 403 3967 6 ppm 998 2410 Rev C Page 15 Appendix D Correcting for High TDGP The C sense output is not compensated for gas pressure and as a result errors can be introduced
11. ice as listed above If Technical Support can assist you by phone or correspondence we will be glad to at no charge Repair service will be billed on a fixed price basis plus any applicable duties and or taxes Shipment to Turner Designs should be prepaid Your bill will include return shipment freight charges Address for Shipment Turner Designs Inc 845 W Maude Ave Sunnyvale CA 94085 998 2410 Rev C Page 11 998 2410 Rev C Page 12 Appendix A Sensor Specifications Parameter Specification Accuracy 3 of full scale Power Consumption 80 mA O 6 VDC 100 mA during warmup Input Voltage 6 12 VDC Signal Output 0 5 VDC Analog Operating Temperature Range 2 to 35 C Water Temperature Detector Non Dispersive Infrared NDIR Detector Stabilization Time 45 seconds 3 minutes tes equilibration time 4 minutes Housing Material Delrin Dimensions LxD 8 0 x 1 97 in 20 3 x 5 0 cm 50 mm 1 97 Depth Rating 600 meters Weight lt 1 Ib 430 g 203 mm 8 0 Figure AA1 Outer dimensions of the C sense 998 2410 Rev C Appendix B Wiring Guide Pin Number Color Function Connection 4 Red Supply Voltage 6 12 VDC Positive E 2 Black Supply Ground 0 VDC Ground Connection PSU 3 White CO2 Analog Signal Out Multimeter Positive 4 0 5 VDC Connection 4 Green Analog Ground Multimeter Ne
12. in conditions typically temperature wait for signal to return 5 15 seconds Water damage Check for water underneath the membrane as well as the location of a possible puncture In the case of water damage factory membrane and detector replacement is reguired Contact Turner Designs Technical Support support turnerdesigns com for an RMA 4 3 The instrument does not read 400 ppm in air A common thought is that the sensor will read 400 ppm in air This is false Typically readings are around 450 ppm outside and anywhere from 500 1500 ppm in buildings and labs 4 4 During lab testing in air the sensor reads too high or shows large fluctuations Human breath contains 40 000 50 000 ppm CO ensure sensor head is pointed away from human exhalation 4 5 Equilibration time is really slow Biofilm or other foreign substance could be on the membrane Follow the cleaning procedure in section 3 2 4 6 Membrane appears loose or bulged This can happen if the sensor was removed from high total dissolved gas pressure water too rapidly and the gas pressure behind the membrane greatly exceeded the hydrostatic pressure Contact Turner Designs Technical Support support turnerdesigns com 998 2410 Rev C Page 9 5 Warranty 5 1 Warranty Terms Turner Designs warrants the C sense and accessories to be free from defects in materials and workmanship under normal use and service for a period of 12 months from the date of shipment fr
13. l Scientific CR1000 For instructions on how to interface the C sense with the CR1000 datalogger see the technical note at the following web address http www turnerdesigns com t2 doc tech notes S 0162 pdf e PMEC sense Logger For instructions on how to interface the C sense with the PME C sense Logger see the manual at the following web address http pme com wp content uploads 2015 02 C sense Logger Manual pdf 998 2410 Rev C Page 20 998 2410 Rev C Page 21
14. o terms are related by pressure and the following eguation pCOz xCO2 P Where P is the pressure measured in atmospheres To convert an output from the C sense of 430 ppm to atm divide the ppm umol mol value of 430 by 1x10 430 umol mol 1x108 mol mol 4 3x10 unitless Then multiply that unitless ratio by the TDGP in units of atm If TDGP is 1 0005 atm first convert to uatm by multiplying by 1x105 resulting in 1000500 atm 4 3x104 1000500 patm 430 2150 patm From this example it follows that differences in the value of pCOo in units pf ppm and units of natm are a function of the TDGP When TDGP is close to or at atmospheric pressure the value of pCO in units of ppm and patm are similar As the TDGP becomes more significant so does the difference between pCO in units of pom and patm A third unit of measure for CO is the fugacity f COz The fugacity corrects for non ideal gas behavior and can be estimated from approximate expressions along with the temperature and pCOz In most cases fCO is within a few atm of the pCO 998 2410 Rev C Page 19 Appendix G Logging Options for the C sense At present there are two supported logging options for the C sense e DataBank Datalogger For instructions on how to interface the C sense with the Handheld DataBank or the DataBank Station see the Ouick Start Guide at the following web address http www turnerdesigns com t2 doc tech notes 998 2906 pdf e Campbel
15. om Turner Designs with the following restrictions e Turner Designs is not responsible for replacing parts damaged by accident or neglect Damage to the sensor or other internal electronics as a result of flooding from either a punctured membrane or an improperly user applied o ring seal is not covered under this warranty Care must be taken to deploy instruments according to procedures described in this manual to minimize the possibility of damage due to flooding Damage from corrosion is not covered Enhanced corrosion activity and damage may result from improper electrical isolation between the C sense and any supporting platforms attached to the instrument Damage caused by customer modification of the instrument is not covered e This warranty covers only Turner Designs products and is not extended to equipment used with our products We are not responsible for incidental or consequential damages except in those states where this limitation is not allowed This warranty gives you specific legal rights and you may have other rights which vary from state to state e Damage incurred in shipping is not covered e Failure of gas permeable membranes are not covered under this warranty e Welded mounting tabs and other mechanisms used to mount Turner Designs instruments to ships buoys mooring lines etc are not covered under this warranty Turner Designs expects the best and safest engineering practices to be applied by knowledgeable and experien
16. the estimate of PCO by the C sense See Appendix D for a discussion on how to correct for TDGP 3 2 Cleaning the Interface Biofilms can develop on the interface and alter the signal and response time of the instrument Regular cleaning will minimize this effect To clean the membrane interface 1 Prepare a cleaning solution in an open container with 50 ml of liguid laundry detergent added to 20 liters of fresh water 2 Place the sensor into the container and using a small water pump direct the flow of solution onto the membrane surface for 30 minutes Drain the container and refill with fresh water only Rinse the interface with fresh water using the water pump for 10 minutes Repeat steps 3 and 4 6 If biofilms remain repeat the process while extending step 2 to between 2 and12 hours O R O Caution Do NOT touch the membrane for any reason The use of any object sponge for example to clean the interface can result in scratching by dragging particles across the membrane surface 998 2410 Rev C Page 8 4 Troubleshooting 4 1 No output voltage Check power connections and ensure power supply is between 6 and 12 V DC Check connector diagram to ensure instrument is wired correctly The sensor is reverse polarity protected however applying power to the output signal pin may result in failure 4 2 Output reading remains at O V 0 8 V or other voltage Detector fault The most probable cause is rapid change
17. when the total dissolved gas pressure TDGP in the liquid being measured is significantly different from the pressure at which the instrument was calibrated Measuring TDGP at all times is preferred but the accuracy of the C sense precludes significant improvement in measuring pCOz by doing so in most cases The instruments are calibrated at or near average sea level atmospheric pressure of 101 3 kPa There are several reasons for deviations of TDGP in natural waters 1 Whenever the ocean and atmosphere are in contact equilibration of TDGP is occurring Therefore changes in atmospheric pressure drive changes in the TDGP of the water column 2 Both natural and anthropogenic processes are responsible for adding to the TDGP of natural waters by generating turbulence at the air sea interface An example of a natural process would be breaking waves while an anthropogenic process would be the disturbance of the water column by mechanisms associated with maritime transport e g boat wakes prop wash 3 Natural processes of respiration and photosynthesis Correcting the C sense signal for deviations in TDGP is simple provided TDGP is known or can be reasonably estimated Each C sense is calibrated at 20 C and an atmospheric pressure at or near 101 3 kPa The actual pressure during calibration is stated on the calibration sheet and should be used in the following equation to calculate a corrected pCOz pCO cor from a measured pCO pCO mea p
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