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Model 43-68, 43-68/1, 43-68/2 Gas Proportional Detector 

 

Ludlum Measurements, Inc. 

Page 6 

February 2011 

Detector Performance 

 
ALPHA PLATEAU:

  Determine the plateau region of the 

background and alpha source counting curves for the applied 
voltage range of 1100-1400 volts. Use 50-volt increments and set 
the counting instrument input sensitivity at 4 mV. The operating 
voltage should be approximately 1250 volts. The background 
count should be 3 cpm or less. The operating voltage will increase 
with a higher input sensitivity. Check each quadrant of the detector 
face for statistically uniform response; that is, ensure that each 
quadrant reading is within 

±

10% of the average of the readings.  If 

the count is not statistically uniform, check for light leaks in the 
window and repeat flush procedures. 

 
BETA-GAMMA PLATEAU:

 Determine the plateau region in the 

background and beta-gamma source counting curves for the 
applied voltage range of 1550 volts to 1900 volts or from 1550 
volts to when either the source or background count rate increases 
dramatically. Use 50-volt increments and leave the input 
sensitivity at 4 mV. The operating voltage should be approximately 
1700-1750 volts, with the background count at 350 cpm or less. 
Setting instrument input sensitivity greater than 4 mV will increase 
the operating voltage. 

 

Static Operation 

 

Check detector for proper operation, for appropriate source 
count, and gas leakage. 

 

 

Disconnect output and input male quick connects. 

Summary of Contents for 159017

Page 1: ...LUDLUM MODEL 43 68 43 68 1 AND 43 68 2 GAS PROPORTIONAL DETECTORS February 2011 Serial Number 159017 and Succeeding Serial Numbers ...

Page 2: ......

Page 3: ...68 43 68 1 AND 43 68 2 GAS PROPORTIONAL DETECTORS February 2011 Serial Number 159017 and Succeeding Serial Numbers LUDLUM MEASUREMENTS INC 501 OAK STREET P O BOX 810 SWEETWATER TEXAS 79556 325 235 5494 FAX 325 235 4672 ...

Page 4: ......

Page 5: ...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 6: ...3 68 2 Gas Proportional Detector Ludlum Measurements Inc February 2011 Table of Contents General 1 Specifications 2 Hook Up 4 Flush 5 Detector Performance 6 Static Operation 6 Recharge 7 Parts List 8 Drawings and Diagrams 9 ...

Page 7: ...3 68 and Model 43 68 1 have the two fittings topside The Model 43 68 fittings are on the same end as the cable connector while the Model 43 68 1 has fittings on opposite corners The Model 43 68 2 fittings are on the narrow side of the end of the detector opposite the handle The cable connector is also located there on the Model 43 68 2 Refer to individual assembly drawings for details Instructions...

Page 8: ...ing gases are also acceptable Gas Recharge expected time of operation on static charge with 0 99 m 39 in cable Gross counting mode is 15 hours or longer Alpha beta mode is 5 hours or longer Background Alpha is 3 counts per minute cpm or less when operating at alpha only plauteau region Beta gamma is typically 350 cpm or less in a 10µR hr field Efficiency 4π geometry typical values for gross counti...

Page 9: ...lpha is typically 1100 1400 volts Operating Voltage Beta gamma is typically 1600 1800 volts Counter Threshold Setting typically 2 5 mV for scaler or gross counting instrument Size 7 4 x 11 7 x 19 8 cm 2 9 x 4 6 x 7 8 in H x W x L Weight 0 9 kg 2 lb Gas Connectors double end shut off quick disconnects ...

Page 10: ...als from interfering with the function of the check valves and should be in place when the detector is operating on a static charge Connect counting gas output and input lines to detector RECOMMENDED EQUIPMENT 1 Dual Stage Regulator allows for better low pressure regulation 2 Needle Valve between second regulator stage and flowmeter for easier flow adjustment 3 Flowmeters range of 0 150 cc min cub...

Page 11: ... cc min or 10 2 cm 4 in of water pressure at 1 2 psi gauge pressure for 15 minutes NOTE A faster flush time can be realized if the output gas line only is removed at the output flowmeter and the flow rate maximized Flush time may be reduced to 5 minutes Note that the quick disconnect fitting should not be removed With the fitting in place gas flows out the connection With the fitting removed a che...

Page 12: ...nt reading is within 10 of the average of the readings If the count is not statistically uniform check for light leaks in the window and repeat flush procedures BETA GAMMA PLATEAU Determine the plateau region in the background and beta gamma source counting curves for the applied voltage range of 1550 volts to 1900 volts or from 1550 volts to when either the source or background count rate increas...

Page 13: ...tatic operation A decrease in detector efficiency should be less than 10 in 15 hours from when the detector is disconnected from the main gas supply for gross counting or 5 hours for alpha beta counting Recharge Connect input and output quick connects Turn main supply to ON at 30 50 cc min for routine recharge or refer to flush procedures for faster flush time ...

Page 14: ...ssembled Model 43 68 2 Gas Probe 47 2017 Body Model 43 68 7342 152 Body Model 43 68 1 7342 161 Body Model 43 68 2 7339 138 Cover Plate 7342 156 Hex Screen 7342 157 Reversible Handle 7342 133 Electrode Plate 7342 146 Window Assembly 4342 097 Screw in C Connector 13 7751 Quick Disconnect Fitting Stem 2 each 13 7912 Quick Disconnect Fitting Pipe 2 each 13 7920 Standoff 8 each 18 8780 Brass Knurled Nu...

Page 15: ...ector Ludlum Measurements Inc Page 9 February 2011 Drawings and Diagrams Assembly View Model 43 68 Drawing 342 x 97 Assembly View Model 43 68 Drawing 339 x 70 Assembly View Model 43 68 1 Drawing 339 x105 Assembly View Model 43 68 2 Drawing 339 x 104 ...

Page 16: ...Model 43 68 43 68 1 43 68 2 Gas Proportional Detector Ludlum Measurements Inc Page 10 February 2011 ...

Page 17: ...Model 43 68 43 68 1 43 68 2 Gas Proportional Detector Ludlum Measurements Inc Page 11 February 2011 ...

Page 18: ...Model 43 68 43 68 1 43 68 2 Gas Proportional Detector Ludlum Measurements Inc Page 12 February 2011 ...

Page 19: ...Model 43 68 43 68 1 43 68 2 Gas Proportional Detector Ludlum Measurements Inc Page 13 February 2011 ...

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