TBM-IC-X-ray Manual
Contents
1. free running so please use a stop watch or wrist watch to determine how long the TBM IC XRAY has been integrating Display Units The pulse rate is factory set to equal 1 0 counts per second in a radiation field of 1 mR h 10 Sv h This is the dose rate display updated every few seconds The update rate is a programmable parameter of the meter See page 10 If the TBM IC XRAY is placed in a 1 mR h 10 Sv h field and left there for exactly one hour the raw counts in the Integrate buffer will be 1 0 count sec X 3600 sec hour 3600 counts This is scaled within the meter by the Integrate Mode Scale Factor Mp m 25 Y Mx 0 0028 and the Integrate Mode Decimal Point Mp m 4 25 Y 2 0 00 parameter settings See page 10 This decimal place setting is equivalent to one digit left shift 3600 total counts X 0028 10 08 left one decimal place 1 008 So that after the one hour period the meter displays 1 01 read as 1 01 mR total dose The meter reading at other time spans is the dose accumulated since the last reset Changing Display Units The display units may be changed between mR to Sv by changing the Integrate Mode Decimal Point and the Rate Input parameters of the CUB5 meter See page 10 for programming instructions and the values to use Unit Equivalencies TBM IC XRAY 080722 4 TECHNICAL ASSOCIATES www drct com sales drct com MODE UNITS RADIATION FIELD Rate mR hr 0 1 1 0 10 100 1000 Rate uSv hr 1 102. 3 Press RST button once to enter module 1 twice for module 2 etc 4 Press SEL to scroll through the settings in that module 5 If display is correct press SEL If not and you wish to change that parameter press RST instead Then make the needed changes and when ready press and hold SEL to store the value Programming Screens Module Step Function As Shipped mR uSv 1 1 Count Modes Mp M4 25 Y 72 ent ud ent ud 1 2 Integrate Mode Decimal Point 0 00 0 0 M m e ss yer 1 3 Integrate Mode Scale Factor calibrate calibrate Mh e 5 e MM 1 4 Counter Reset At Power Up No No 1 5 User Input T6 0 Uge pro loc pro loc 2 1 Rate Enable O gt Yes Yes 2 2 Rate Decimal Point O84 2K 0 0 0 2 3 Rate Display O8 gt 26 10000 0 10000 2 4 Rate Input O8 gt USP 10000 0 1000 2 5 Min Display Refresh Seconds 02 0 02 0 GOgTr24 2 6 Max Display Refresh Seconds PH YF24 12 0 12 0 3 1 Select Enable 26 6 0 Yes Yes 3 2 Reset Enable 064 22 Yes Yes 3 3 Display Scroll 266 emooOe No No 3 4 Program Security Code 000 000 3 5 Fact Set No No 4 1 2 9 Alarm Set See CUB 5 Instructions Programming modules 4 and 5 deal with the optional Alarm and Serial accessories Move the slide switch back to the left to lock the program and operate the instrument Replace the top panel and tighten the thumb screws TBM IC XRAY 080722 10 TECHNICAL ASSOCIATES www drct com sales drct com RECOMMENDED PARTS LIST DE
3. 100 1000 10 000 Total Dose mR 0 0016 0 016 0 16 1 6 16 Total Dose uSv 0 016 0 16 1 6 16 160 Total Dose in this table is that dose accumulated during one minute of exposure to the radiation field of the table column COUNT PULSES LED This LED is near the battery LED It flashes green increasing in intensity as count rate increases This is a two 2 color LED GREEN for normal counts RED and Green together for Over Range above 10 R hr The Over Range condition is at 10 R hr when the meter is in either Dose Rate or Total Dose mode BATTERY TEST Press the button labeled TEST The red LED labeled BAT OK will go on if the battery supply is 4 Volts or above BATTERY REPLACEMENT To replace the 6 AA batteries 1 Unscrew the 2 thumbscrews which hold the rear cover plate on to the instrument Remove this cover plate with its attached battery holder Remove the old batteries and slide the 6 new batteries into place Be careful to use the correct polarity for each cell Reinstall battery holder and battery cover plate You may wish to tape batteries into holder if rough handling or shipping is expected PAH WN Use any manufacturer s 1 5 Volt AA batteries as replacements All six batteries should be identical of the same manufacturer and of close to the same purchase date Do not use cells of other than 1 5 Volts e g NiCd which are 1 2 Volt See the Maintenance and Trouble Shooting section regarding the chamber bias ba
4. and slowly over the end of the ion chamber In the event that the Alpha window becomes torn or damaged turn the instrument off The chamber will need to be replaced with a new one Leave the chamber on until a new one is on hand to minimize discharge of the bias batteries Please see the section on Maintenance and Trouble shooting for further information CALIBRATION The TBM IC XRAY should be checked periodically for accuracy at least annually Verify that the reading is within plus or minus 10 at 2 points on each decade Please note the section below on calibration correction factors when checking or recalibrating the unit Calibration of this instrument is accomplished by adjusting how much chamber current is needed to produce each pulse The number of pulses accumulated is one count sec for 1 mR hr Thus 100 counts accumulated in 1 second will read out correctly as 100 mR hr If one count is recorded every 10 seconds then the display will read 0 1 mR hr Calibrate the TBM IC XRAY with the shield installed and the 10 cm window pointing toward the source Use the distance from about an inch behind the front face of the shield to the source to determine the field strength at the meter Calibration Procedure 1 Turn on instrument wait 4 minutes 2 Use front panel button to test batteries TBM IC XRAY 080722 6 TECHNICAL ASSOCIATES www drct com sales drct com 3 Place TBM IC XRAY at highest available calibrated radiation fiel
5. SCRIPTION PART USED Beta Cap A9926 VC2500 16 1 Ion Chamber Shell Includes Alpha Window A9705 1 lon Chamber Base A9706 1 Center Electrode Graphite coated A9911 1 Spring for Center Electrode SP IC3V 1 Digital Display 53300 405 1 Battery Holder for six 6 AA cells BHGAA 1 Battery cover plate with Holder for 6 AA A9946 1 Thumb Screws to hold lid or battery cover 58 28 506 24 4 Batteries Main Battery Pack Bias Battery Stack Number of Cells 6 15 Voltage per Cell 1 5 V 3V Type Alkaline Lithium Capacity 2850 mAh 38 mAh Size AA 2 X 0 55 0 450 X 0 075 Manufacturer Energizer Renata Part Number E91 CR 1220 Service Life 1000 Hours 7 Years Or equivalent TBM IC XRAY 080722 11
6. TECHNICAL ASSOCIATES OPERATION AND MAINTENANCE MANUAL TBM IC X RAY X RAY COMPLIANCE TEST METER Direct Scientific www drct com tel 310 589 0601 fax 310 919 2981 email sales drct com TECHNICAL ASSOCIATES www drct com sales drct com OPERATION AND MAINTENANCE MANUAL TBM IC X RAY TABLE OF CONTENTS Page 1 General 3 2 Range 3 3 Principle Of Operation 3 4 Preamplifier 3 5 Digital Readout 4 5a Integrate Feature 4 5b Display Units 4 5c Changing Display Units 4 5d Unit Equivalencies 5 6 Count Pulses Led 5 7 Battery Test 5 8 Battery Replacement 5 9 Ion Chamber 5 10 Calibration 6 10a Calibration Correction Factors 7 11 Zero Set 8 12 Maintenance And Trouble Shooting 9 13 Programming 10 14 Recommended Parts List 11 DRAWINGS B 9704 Top View lid removed 2 Pages A 10679 Electrometer Box Lid Labeling A 12933 Front Panel Artwork Red Lion Ratemeter Manual Model CUB5 TBM IC XRAY 080722 2 TECHNICAL ASSOCIATES www drct com sales drct com GENERAL The TBM IC XRAY is a small Ion Chamber Radiation Monitor It has a removable stainless steel shield which fits over the ion chamber The shield has a 10 cm circular window for X Ray equipment compliance testing to the specifications of 21 CRF 1020 40 c 1 amp 1 the section of the Code of Federal Regulations covering Cabinet X Ray equipment The TBM IC XRAY has been calibrated with the shield installed with the 10 cm window pointing toward the source
7. When used without the shield as a general purpose radiation detector it will read higher than the actual field strength See the Test Data shipped with the instrument for a correction factor For use in testing Cabinet X Ray equipment preliminary testing should be done with an instrument giving wide area coverage The TA P 8 NEON is ideal or use the TBM IC XRAY with the shield removed When a suspect area is discovered recheck it with the TBM IC XRAY by reinstalling shield with the 10 cm aperture Check at the specified distance from the X Ray generator The TBM IC XRAY may be ordered with a display calibrated in uSv instead of mR and it may be converted between the two by simple reprogramming of the display parameters RANGE Dose Rate 0 1 mR hr to 10 000 0 mR hr 1 uSv hr to 100 000 uSv hr Dose 0 01 mR to 99 999 99 mR 0 1 uSv to 999 999 9 uSy Display time constant 12 seconds from 0 to 2mR h and 2 3 seconds above 2 mR h PRINCIPLE OF OPERATION Ionizing radiation such as X Rays Gamma Rays and mid to high energy Beta particles enter the Ion chamber The air in the lon Chamber becomes ionized The chamber wall is at a negative potential and the antenna on the chamber axis is positive Ionization generates a small current across the chamber This very small chamber current is amplified and converted to pulses which are counted by the display module and shown on the front panel readout as Dose Rate The pulses are also accumulated
8. a correction factor 1 Remove the shield 2 Install the Beta Cap 3 Place the unit in a known field with the ion chamber axis perpendicular to the direction of the calibration source and the axis on the distance mark for the known field strength 4 Record the field strength and meter reading 5 Repeat for two points in each decade 6 Divide each field strength by the corresponding meter reading Use the average of these values as the correction factor The following measurements were made in a field of 100 mR hr Sleeve installed No Sleeve Front to Source 100 132 Side to Source 130 138 Calibration Correction Factors These instruments are calibrated in international roentgens corrected to 71 6 F 22 C and 29 92 inches Hg TBM IC XRAY 080722 7 TECHNICAL ASSOCIATES www drct com sales drct com The TBM IC XRAY electronics are fully temperature compensated in ambient temperature range As in all free air lon Chambers thermal air expansion and atmospheric pressure variations result in sensitivity changes These changes are on the order of 0 4 per degree C and 3 5 per in Hg which meets all standard portable instrument requirements However even this may be eliminated by the following correction factors 459 7 T 273 15 T Temperature MP or MM 331 3 293 15 Atmospheric Pressure eu P in inches Hg Example A radiation measurement is taken and the meter reading is 25 mR hr The air temperature is 90 degre
9. and may be displayed instead as an Integrated Dose When the shield is in place radiation entering the 10 cm window dominates the reading PREAMPLIFIER The pre amplifier is a current to voltage amplifier This is a very high input impedance amplifier with high meg feedback resistors The input current starts from sub picoampere range The input is susceptible to noise pick up static charge etc if the metal cover is removed from the internal metal E Box The amplified voltage drives a pulse generator which in turn feeds into the LCD counter display module TBM IC XRAY 080722 3 TECHNICAL ASSOCIATES www drct com sales drct com DIGITAL READOUT The front panel is an 8 digit LCD digital readout The meter is a Red Lion CUB5 with programmable parameters The user manual is included at the end of this manual See page 10 for programming instructions and the settings as shipped for operation in both mR and uSv Integrate Feature The front panel display has both Rate Dose Rate and Integrate Accumulated Dose data buffers in operation all the time You can look at either without disturbing the other by pressing the left Select button SEL on the meter e To reset the Integrate buffer push right hand button RST The user can disable this button if required See programming section of manual This is useful if you wish to prevent inadvertent or unauthorized reset during a long integration measurement e The integrate function is
10. d in uSv MAINTENANCE AND TROUBLE SHOOTING When calibrating the instrument if reading is low 1 Check the meter programming see page 10 2 Check wiring 3 Calibrate the TBM IC XRAY by adjusting RANGE pot on the E Box and zero adjust dial on the front panel See the section on Calibration above If the readings are still low check the bias voltage The bias batteries should last in service for the full 7 years of their rated shelf life To check the 45 Volt bias batteries 1 Loosen the screws on the ring at the base of the chamber 2 Unscrew the ion chamber and set it aside 3 Use the side of the positive meter probe along the side of the antenna and the negative probe on the gray graphite area on the face of the unit 4 If the voltage has fallen below 30 the bias batteries need to be replaced 5 Call TA for bias battery replacement instruction sheet TBM IC XRAY 080722 9 TECHNICAL ASSOCIATES www drct com sales drct com PROGRAMMING NOTE TBM IC XRAY is shipped in Program Lock Out Mode Model TBM IC XRAY incorporates a programmable display The program parameters are in non volatile memory and are retained when unit is turned on or off and even if the 6 AA batteries are removed To make changes in the programming parameters Ref CUB5 user manual included at the back of this manual 1 Loosen thumb screws and remove top panel Move slide switch to the right to the OP position 2 Hold SEL button for 2 seconds
11. d point but not exceeding 10 R hr and no less than 100 mR hr 4 Loosen the 2 thumbscrews on instrument panel and lift up front panel Do Not disconnect any wires or the ribbon cable 5 This exposes E box lid See Drawing B10679 at back of this manual 6 Rotate the recessed RANGE potentiometer counter clockwise to increase display reading or clockwise to decrease reading as needed until the display shows correct radiation field value within desired error limits 7 Place TBM IC XRAY at 0 2 mR hr or other low field but not exceeding 2 mR hr 8 Adjust the front panel 10 turn dial to achieve correct meter reading clockwise turn increases readings 9 Repeat steps 6 through 8 10 Move to location where field is low Preferably 10 20 micro R hr 11 Verify that display reads zero most of the time It may occasionally read higher due to counting statistics or shot noise in the pre amp 12 Press SET button on the top instrument panel Hold button down for 15 seconds if display reads 2 0 the calibration procedure is finished 13 If it does not read 2 0 continue holding the SET button and slowly adjust recessed pot marked SET on E box lid just to the left of the ribbon cable until 2 0 reading is achieved 14 Recheck the unit at 2 points on each decade This reading is 20 when the instrument is set to read in Sv To use the TBM IC XRAY without the shield as a general purpose Gamma ray and X ray detector calculate
12. es F and the barometric pressure is 29 13 in Hg 459 7 90 _ 549 7 Temperature 1 035 531 3 531 3 Pressure n 1 027 29 13 Correction factor 1 035 x 1 027 1 063 Corrected reading 25mR hr x 1 063 26 6 mR hr The effects of air temperature and pressure must be taken into consideration when these instruments are re calibrated or when the calibration is checked ZERO SET On the left side of the TBM IC XRAY front panel are the Zero Set Controls consisting of the SET button and ten turn dial 1 Take the instrument to a location where background radiation field is not elevated above the normal nominal 015 mR h Turn on TBM IC XRAY and wait 2 minutes Rotate the thumb lock to unlock the ten turn dial Press and hold SET button Hold button down for 20 seconds Display will show the number given on your calibration certificate usually 2 0 If display does not show this number then continue to hold down SET button and adjust ten turn dial a small amount until correct number is shown Note The physical rotation of the pot may cause a temporary overshoot in the reading so please observe reading for 20 seconds to be sure 2 0 0 1 reading is stable 8 Rotate the thumb lock to lock the ten turn dial 9 Release SET button and wait 10 seconds for Rate display to settle YOO BR WN TBM IC XRAY 080722 8 TECHNICAL ASSOCIATES www drct com sales drct com This reading is 20 when the instrument is set to rea
13. ttery cells They should last for their rated 7 year shelf life ION CHAMBER WARNING Ion Chamber should not be opened unnecessarily A temporary zeto shift may occur and unit will read too high for several days The TBM IC XRAY ion chamber consists of e A white plastic 3 by 3 diameter cylinder Sealed on the outer end with a light tight mylar window the Alpha window TBM IC XRAY 080722 5 TECHNICAL ASSOCIATES www drct com sales drct com e Coated with conductive graphite inside and on the mounting threads e lt A red plastic cap the Beta cap which slides onto the front of the cylinder e lt A separate stainless steel shell which slips on over the cylinder Installed as shipped e A black plastic cover protects the Alpha window The Alpha window is 0 5 mg cm It is made integrally with the cylinder and the whole chamber must be replaced if it breaks The Beta Cap must be removed e To allow measurement of Alpha low energy Betas and very low energy X Rays e To slide on the shielding sleeve for measurement through a 10 cm window WARNING When the Alpha window is exposed it can be very easily damaged Do not contact the exposed mylar window Do not cover the air holes when removing or installing the beta cap The air pressure difference may rupture the Alpha window To remove the red Beta cap be sure the air vents are not covered then gently pull it off the ion chamber To reinstall the Beta cap slide it gently
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