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Ludlum Measurements 239605, Manual

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Ludlum Measurements 239605 Manual Download Page 7

Model 3-IS & 3-IS-1 

Technical Manual 

 

Ludlum Measurements, Inc. 

 

October, 2010 

 

Summary of Contents for 239605

Page 1: ...LUDLUM MODEL 3 IS AND 3 IS 1 INTRINSICALLY SAFE SURVEY METER October 2010 Serial Number 239605 and Succeeding Serial Number ...

Page 2: ...ng A special cable Part Number 8303 764 xx where xx represents a length in feet is supplied with the Model 3 IS If replacement is needed ensure that the same type is used This cable is identified by type C connectors with locking screws and a light blue molded rubber strain relief Cable lengths are available up to 37 feet LUDLUM MEASUREMENTS INC 501 OAK STREET P O BOX 810 SWEETWATER TEXAS 79556 32...

Page 3: ......

Page 4: ...anty of merchantability or fitness which extend beyond the description of the face there of If the product does not perform as warranted herein purchaser s sole remedy shall be repair or replacement at the option of Ludlum Measurements In no event will Ludlum Measurements be liable for damages lost revenue lost wages or any other incidental or consequential damages arising from the purchase use or...

Page 5: ...Model3 IS 3 IS 1 TechnicalManual Ludlum Measurements Inc October 2010 ...

Page 6: ...Model3 IS 3 IS 1 TechnicalManual Ludlum Measurements Inc October 2010 ...

Page 7: ...Model3 IS 3 IS 1 TechnicalManual Ludlum Measurements Inc October 2010 ...

Page 8: ...Meter Face Dial 2 3 Operational Check 2 6 Specifications 3 Identification of Controls and Functions 4 Safety Considerations 5 Environmental Conditions for Normal Use 5 1 Connecting a Detector to the Instrument 5 1 Warning Markings and Symbols 5 2 Cleaning and Maintenance Precautions 5 3 Calibration and Maintenance 6 Calibration 6 1 Exposure Rate Calibration 6 2 CPM Calibration 6 2 Establishing an ...

Page 9: ...Scintillators 7 4 Technical Theory of Operation 8 Low Voltage Supply 8 1 High Voltage Supply 8 1 Detector Input 8 1 Amplifier 8 1 Discriminator 8 2 Audio 8 2 Scale Ranging 8 2 Meter Drive 8 2 Meter Reset 8 2 Fast Slow Time Constant 8 2 Recycling 9 Parts List 10 Model 3 IS Survey Meter 10 1 Main Board Drawing 464 355 10 1 Safety Board Drawing 464 361 10 3 Wiring Diagram Drawing 464 358 10 4 Drawing...

Page 10: ...and meter housing are made of cast aluminum and the can is 0 090 thick aluminum The audio provides a brief click for every radiation event detected It also provides a steady tone to warn the user of a low battery condition This low battery warning overrides the position of the AUD ON OFF switch There are three Geiger Mueller GM detectors which are qualified for use with the Model 3 IS Additionally...

Page 11: ...e D batteries To reduce the risk of ignition of a flammable or explosive atmosphere batteries must be changed only in a location known to be a non hazardous area Warning When repairing this unit substitution of components may impair INTRINSIC SAFETY Avertissement La substitution de composants peut compromettre la SECURITE INTRINSEQUE Afin de prevenir I Inflammation D Atmospheres dangereuses ne cha...

Page 12: ... detectors and instruments are not interchanged Each instrument is calibrated to specific detector s and therefore not interchangeable To return an instrument for repair or calibration provide sufficient packing material to prevent damage during shipment Also provide appropriate warning labels to ensure careful handling Include detector s and related cable s for calibration Include brief informati...

Page 13: ...arning A special cable Part Number 8303 764 xx where xx represents a length in feet is supplied with the Model 3 IS If replacement is needed ensure that the same type is used This cable is identified by type C connectors with locking screws and a light blue molded rubber strain relief Cable part number is 8303 764 xx where xx represents a length in feet Cable lengths are available up to 37 feet Co...

Page 14: ...than the F position The detector cable on the Model 3 IS only can be a source of problems Test the detector cable by bending or flexing either end of the cable and checking for an increase in the rate of counts detected Replace the cable if increases in the rate of counts are detected Check the meter reset function by depressing the RES pushbutton switch and ensuring the meter needle drops to 0 On...

Page 15: ... 1 scale multiple then the reading is 3 5 kcpm multiplied by 0 1 350 cpm The same needle indications on successive ranges would be 1 3 5 kcpm or 3 500 cpm 10 35 kcpm or 35 000 cpm 100 350 kcpm or 350 000 cpm A typical dual scale two arcs meter face is shown below The top scale reads 0 2 mR hr The bottom scale also reads 0 2 mR hr and is for 100 only scale The 100 ONLY scale will work correctly whe...

Page 16: ...near mR hr scale is commonly referred to as a combo meter face since it has both count rate cpm and exposure rate mR hr arcs Simpler meter faces may only have a count rate or an exposure rate arc s like the previous meter faces shown A combo meter face is specifically designed for a particular detector In the example above the 1 0 mR hr mark on the middle arc lines up with 3 3kcpm on the upper arc...

Page 17: ...between calibrations an instrument operational check including battery test and instrument test as described above should be performed at least daily or prior to use whichever is less frequent A reference reading or readings with a check source should be obtained with the detector s in a constant and reproducible manner at the time of calibration or at the time the instrument is received in the fi...

Page 18: ...battery condition High Voltage adjustable from 400 to 1100 volts Threshold fixed at 40 mV 10 mV Meter 6 4 cm 2 5 inch arc 1 mA analog type Meter Face Typically 0 2 mR hr or 0 5k cpm BAT TEST others available Model 3IS 1 is 0 10 mR hr BAT TEST Range typically 0 200 mR hr or 0 500 000 counts minute cpm M3IS 1 is 0 1 mR hr to 1 0 R hr Linearity reading within 10 of true value with detector connected ...

Page 19: ...sleet and snow Cable Model 3 IS only a special 39 inch coaxial cable with set screw locking C connector and light blue molded rubber strain relief is provided with each instrument Warning Model 3 IS only A special cable is supplied Part Number 8303 764 xx where xx represents a length in feet with the Model 3 IS If replacement is needed ensure that the same type is used This cable is identified by ...

Page 20: ...heck scale on the meter provides a visual means of checking the battery charge status Moving the range selector switch to one of the range multiplier positions 100 10 1 and 0 1 provides the operator with an overall range of 0 to 500 000 cpm Multiply the scale reading by the multiplier to determine the actual scale reading Calibration Controls Recessed potentiometers which are used to calibrate the...

Page 21: ...ovides meter response Selecting the fast F position of the toggle switch provides 90 of full scale meter deflection in four seconds In the slow S position 90 of full scale meter deflection takes 22 seconds In F position there is fast response and large meter deviation The S position should be used for slow response and damped meter deviation Note The slow response position is normally used when th...

Page 22: ...64 Connecting a Detector to the Instrument Caution The detector operating voltage HV is supplied to the detector via the detector input connector A mild electric shock may occur if you make contact with the center pin of the input connector Switch the Model 3 IS range selector switch to the OFF position and wait for 60 seconds before connecting or disconnecting the cable or detector Warning A spec...

Page 23: ...64 No B 3 1 designates hazardous live voltage and risk of electric shock During normal use internal components are hazardous live This instrument must be isolated or disconnected from the hazardous live voltage before accessing the internal components This symbol appears on the front panel Note the following precautions Warning The operator is strongly cautioned to take the following precautions t...

Page 24: ...with a damp cloth using only water as the wetting agent Do not immerse the instrument in any liquid Observe the following precautions when cleaning or performing maintenance on the instrument 1 Turn the instrument OFF and remove the batteries 2 Allow the instrument to sit for 1 minute before cleaning the exterior or accessing any internal components for maintenance ...

Page 25: ...ed below Unless otherwise specified the instrument is calibrated to exposure rate at the factory Note Measure High Voltage with a Model 500 Pulser or a High Impedance voltmeter with a high meg probe If one of these instruments is not available use a voltmeter with a minimum of 1000 megohm input resistance Calibration shall include response evaluations and adjustment for two points of each scale of...

Page 26: ...tector so the field corresponds to approximately 20 of full scale meter deflection Confirm that the meter reading is within 10 of the field Repeat this process for the 10 1 and 0 1 ranges If your gamma exposure range cannot calibrate two positions on each scale the Pulser may be used to electronically calibrate the remaining points Reconnect the Pulser to the instrument and determine the count rat...

Page 27: ... ranges Note In the event that any reading is not within 10 of the true value on any scale after any of the above calibration methods is performed a reading within 20 of true value shall be acceptable if a calibration graph or chart is provided with the instrument Instruments that cannot meet these criteria are defective and require repair Establishing an Operating Point The operating point for th...

Page 28: ...he energy of the detected radiation The GM detectors for this unit operate at 900 volts Scintillators Scintillation type detectors have a wide gain spectrum typically 1000 1 at a single operating point An operating voltage versus count rate curve plateau must be established to determine the proper operating voltage The operating voltage is typically set above the knee of the plateau Plot the HV ve...

Page 29: ...ning battery replacement or detector cable replacement Note Ludlum Measurements Inc recommends recalibration at intervals no greater than one year Check the appropriate regulations to determine required recalibration intervals Ludlum Measurements offers a full service repair and calibration department We not only repair and calibrate our own instruments but most other manufacturer s instruments Ca...

Page 30: ... Measurements Inc Page 6 6 October 2010 Note Never store the instrument over 30 days without removing the batteries Although this instrument will operate at very high ambient temperatures battery seal failure may occur at temperatures as low as 100 F ...

Page 31: ...ector cables 2 sticky meters 3 battery contacts Note that the first troubleshooting tip is for determining whether the problem is with the electronics or with the detector A Ludlum Model 500 Pulser is invaluable at this point because of its ability to simultaneously check high voltage input sensitivity or threshold and the electronics for proper counting We hope these tips will prove to be helpful...

Page 32: ...the HV ensure that one with high impedance is used as a standard Multimeter could be damaged in this process 2 Check for noise in the detector cable by disconnecting the detector placing the instrument on the lowest range setting and wiggling the cable while observing the meter face for significant changes in readings 3 Check for sticky meter movement Does the reading change when you tap the meter...

Page 33: ...ute a known good detector and or cable 2 Has the correct operating voltage been set Refer to the calibration certificate or detector instruction manual for correct operating voltage If the instrument uses multiple detectors confirm that the high voltage is matched to the current detector being used 1 Ensure that the AUD ON OFF switch is in the ON position 2 Remove the instrument housing and check ...

Page 34: ...roblem Note When replacing the window make sure to use a window made with the same thickness mylar and the same number of layers as the original window 2 Verify that the HV and input sensitivity are correct Alpha and gamma scintillators typically operate from 10 35 mV High voltage varies with the photomultiplier tubes PMT from as low as 600 Vdc to as high as 1100 Vdc 3 On a gamma scintillator visu...

Page 35: ...ltage is coupled back through R39 to pin 8 of U13 High voltage output is set by front panel potentiometer R42 which sets the voltage feedback of 1 31 Vdc to pin 8 of U13 R38 and C28 provide filtering Detector Input Detector pulses are coupled from the detector through C6 to amplifier input pin 2 of U4 CR1 protects U4 from input shorts R37 couples the detector to the high voltage supply Amplifier A...

Page 36: ... R22 and C7 Scale Ranging Detector pulses from the discriminator are coupled to univibrator pin 5 of U9 For each scale the pulse width of pin 6 of U9 is changed by a factor of 10 with the actual pulse width being controlled by the front panel switch the analog switches U1 and U2 and the related potentiometers This arrangement allows the same current to be delivered to C9 by 1 count on the 0 1 rang...

Page 37: ...but simply desires to inform its consumers of the range of recyclable materials present in its products so that the user will have flexibility in following all local and federal laws The following types of recyclable materials are present in Ludlum Measurements Inc electronics products and should be recycled separately The list is not all inclusive nor does it suggest that all materials are presen...

Page 38: ... 04 5755 C3 0 0047µF 100V 04 5669 C4 10pF 100V 04 5673 C5 0 01µF 50V 04 5664 C6 100pF 3KV 04 5735 C7 0 022µF 50V 04 5667 C8 1µF 16V 04 5701 C9 10µF 25V 04 5655 C10 100pF 100V 04 5661 C11 68µF 10V 04 5654 C12 10µF 25V 04 5728 C14 470pF 100V 04 5668 C15 220pF 100V 04 5674 C16 68µF 10V 04 5654 C17 47µF 10V 04 5666 C18 C27 0 001µF 500V 04 5734 C29 10µF 25V 04 5655 C30 C31 1µF 16V 04 5701 C32 470pF 100...

Page 39: ... 07 6411 CR3 CR7 CMPD2005S 07 6468 CR9 RECTIFIER CMSH1 40M 07 6411 SW1 D5G0206S 9802 08 6761 SW2 TP11LTCQE 08 6770 SW3 SW4 7101SDCQE 08 6781 R33 250K 64W254 100 09 6819 R34 250K 64W254 1009 6819 R35 500K 64W504 1 09 6850 R36 250K 64W254 0 1 09 6819 R42 1 2M 3296W HV 09 6957 R1 R5 200K 1 8W 1 12 7992 R6 8 25K 1 8W 1 12 7838 R7 10K 1 8W 1 12 7839 R8 2 37K 1 8W 1 12 7861 R9 R11 10K 1 8W 1 12 7839 R12...

Page 40: ...8 1K 1 8W 1 12 7881 R28 100K 1 8W 1 12 7834 R29 1K 1 8W 1 12 7832 R30 100K 1 8W 1 12 7834 R31 475K 1 8W 1 12 7859 R32 100K 1 8W 1 12 7834 R37 100K 1 8W 1 12 7834 R39 500M 3KV 2 12 7031 R40 604K 1 8W 1 12 7889 R43 14 7K 1 4W 1 12 7068 R44 1K 1 4W 1 12 7832 P1 640456 5 MTA10013 8057 P2 640456 6 MTA100 installed as required 13 8095 P3 640456 2 MTA10013 8073 L1 22 µH 21 9808 T1 31032R 21 9925 BOARD Co...

Page 41: ...asurements Inc Page 10 4 October 2010 Reference Description PartNumber Model 3 IS 1 Detector Board 5408 267 R2 1 MEG 1 4W 5 10 7028 V1 GM Tube LND72611 01 5011 M1 Meter 4363 188 R1 25 ohm 2 5W 5 12 7245 Wiring Diagram Drawing 464 358 BOARD MISCELLANEOUS ...

Page 42: ...surements Inc Page 11 1 October 2010 Drawings MAIN CIRCUIT BOARD Drawing 464 355 3 sheets MAIN CIRCUIT BOARD LAYOUT Drawing 464 356 2 sheets SAFETY BOARD Drawing 464 361 SAFETY BOARD LAYOUT Drawing 464 362 CHASSIS WIRING DIAGRAM Drawing 464 358 Section 11 ...

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