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Summary of Contents for Ludlum Measurements 12SA
- Page 1 LUDLUM MODEL 12SA SURVEY METER July 2020 Serial Number 349200 and Succeeding Serial Numbers...
- Page 2 LUDLUM MODEL 12SA SURVEY METER July 2020 Serial Number 349200 and Succeeding Serial Numbers...
- Page 3 RETURN OF GOODS TO MANUFACTURER If equipment needs to be returned to Ludlum Measurements, Inc. for repair or calibration, please send to the address below. All shipments should include documentation containing return shipping address, customer name, telephone number, description of service requested, and all other necessary information.
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Page 5: Table Of Contents
Identification of Controls and Functions Safety Considerations Environmental Conditions for Normal Use Warning Markings and Symbols Cleaning and Maintenance Precautions Maintenance Recalibration Batteries Technical Theory of Operation Input Amplifier Discriminator Scale Ranging Digital Analog Converter Audio Meter Drive Ludlum Measurements, Inc. July 2020... - Page 6 Model 12SA Survey Meter Technical Manual Meter Compensation Fast/Slow Time Constant Low Voltage Supply Low Voltage Reference High Voltage Supply Alarm Recycling Radiation Basics Radiation and Life The Unstable Atom Radioactive Decay Ionizing Radiation Measuring Ionizing Radiation What are the Health Risks from Ionizing Radiation?
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Page 7: Introduction
The instrument is capable of using either standard ˝D˝ cell flashlight batteries or nickel-cadmium rechargeable batteries. However, the Model 12SA does not include circuitry for recharging the batteries. The two ˝D˝ cell batteries are located in an isolated compartment, easily accessible from the front panel. -
Page 8: Getting Started
(batteries, cable, etc.) and ensure that all of the items listed on the packing list are in the carton. Check individual item serial numbers and ensure calibration certificates match. The Model 12SA serial number is located on the front panel below the battery compartment. -
Page 9: Battery Test
Turn the range selector switch to the ×10 position. If no source of radiation is nearby, any meter deflection should be due to background radiation. At Ludlum Measurements, a typical background reading is 6-12 µR/hr (0.06- 0.12 µSv/h). Expose the instrument to a check source with the source oriented with the... -
Page 10: Surveying For Radiation
Model 12SA Survey Meter Technical Manual Section 2 Audible beeps should be heard with increasing frequency as the source is brought closer to the detector, and as the meter needle deflects upscale. Ensure that the lamp and constant audible tone are activated when... -
Page 11: Radiation Limits
Model 12SA Survey Meter Technical Manual Section 2 and other conditions. When surveying for radiation, locating and measuring excess radiation above background is the main focus. Radiation is also generated in a range of medical, commercial and industrial activities. The most familiar, and in national terms, the largest of these sources of exposure is medical X-rays. -
Page 12: False Alarms
Example: Using this dose limit (no more than 2 mR [0.02 mSv] in any one hour), if the Model 12SA reads ˝3˝ while in the ×1000 range, a non-radiation worker would be allowed in the radiation field for no longer than 40 minutes. - Page 13 Model 12SA Survey Meter Technical Manual Section 2 Meter readings registering above background and activated alarm indicators may commonly be caused by either of the conditions just described. However, careful survey should be performed to limit the cause of the high reading to one of the described conditions or to a particular area of high radiation (“hot-spot”).
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Page 14: Specifications
Model 12SA Survey Meter Technical Manual Section 3 Section Specifications Detector : 2.5 x 2.5 cm (1 x 1 in.) sodium iodide (NaI)T1 scintillator : typically 175 cpm/µR/hr ( Cs gamma) Sensitivity : reading within 10% of true value. This instrument may... - Page 15 Model 12SA Survey Meter Technical Manual Section 3 : cast and drawn aluminum with beige powder-coat finish Construction and silk-screened nomenclature : 22.2 x 21.6 x 8.6 cm (8.8 x 8.5 x 3.4 in.) (H x W x L), including...
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Page 16: Identification Of Controls And Functions
Model 12SA Survey Meter Technical Manual Section 4 Section Identification of Controls and Functions Range Selector Switch : a six-position switch marked , ×1000, ×100, ×10, and ×1. When placed in the position, battery charge status is indicated on the meter face. Moving the range selector switch to one of the range multiplier positions (×1000, ×100, ×10, or ×1) - Page 17 Model 12SA Survey Meter Technical Manual Section 4 : When depressed, this switch provides a rapid RESET Pushbutton means of driving the meter needle to zero. : Three indentations on the top and sides of Crystal (detector) center the instrument canister (“can”) give indication of the crystal center where the points intersect.
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Page 18: Safety Considerations
Model 12SA Survey Meter Technical Manual Section 5 Section Safety Considerations Environmental Conditions for Normal Use Indoor or outdoor use No maximum altitude Temperature range of -20 to 50 °C (-4 to 122 °F); may be certified for operation from -40 to 65 °C (-40 to 150 °F) -
Page 19: Cleaning And Maintenance Precautions
Cleaning and Maintenance Precautions The Model 12SA may be cleaned externally 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. -
Page 20: Maintenance
Maintenance nstrument maintenance consists of keeping the instrument clean and periodically checking the batteries and the calibration. The Model 12SA instrument may be externally cleaned with a damp cloth (using only water as the wetting agent). Do not immerse the instrument in any liquid. -
Page 21: Batteries
Model 12SA Survey Meter Technical Manual Section 6 Batteries The batteries should be removed any time the instrument is placed into storage. Battery leakage may cause corrosion on the battery contacts, which must be scraped off and/or washed using a paste solution made from baking soda and water. -
Page 22: Technical Theory Of Operation
Model 12SA Survey Meter Technical Manual Section 7 Section Technical Theory of Operation Input Detector pulses are coupled from the detector through C57 to emitter follower Q96. R83 and R89 provide bias. R137 protects Q96 from input shorts. R27 couples the detector to the high-voltage supply. -
Page 23: Audio
Model 12SA Survey Meter Technical Manual Section 7 drained off by R74. The voltage across C105 is proportional to the incoming count rate. Audio Discriminator pulses are coupled to univibrator pin 12 of U3. The front- panel selector controls the reset at pin 13 of U4. When... -
Page 24: High Voltage Supply
Model 12SA Survey Meter Technical Manual Section 7 High Voltage Supply High voltage is developed by blocking oscillator Q145-T165 and rectified by voltage multiplier CR166, 167, 169, and 175. Output voltage increases as current through Q44 increases, with maximum output voltage with Q44 saturated. -
Page 25: Recycling
To this end, Ludlum Measurements, Inc. strives to supply the consumer of its goods with information regarding reuse and recycling of the many different types of materials used in its products. With many different agencies –... -
Page 26: Radiation Basics
Model 12SA Survey Meter Technical Manual Section 9 Section Radiation Basics Radiation and Life Adapted from Eric J. Hall’ s book, “Radiation and Life” Radiation is energy traveling through space. Sunshine is one of the most familiar forms of radiation. It delivers light, heat, and suntans. We control its effect on us with sunglasses, shade, air conditioners, hats, clothes, and sunscreen. -
Page 27: The Unstable Atom
Model 12SA Survey Meter Technical Manual Section 9 The Unstable Atom Radiation comes from atoms, the basic building blocks of matter. Most atoms are stable; a carbon-12 atom, for example, remains a carbon-12 atom forever, and an oxygen-16 atom remains an oxygen-16 atom forever, but certain atoms eventually disintegrate into a totally new atom. -
Page 28: Radioactive Decay
Model 12SA Survey Meter Technical Manual Section 9 1 kg (2.2 lb) of uranium ore (Australian, 13.51 X 10 0.3%) 1 kg (2.2 lb ) of low-level radioactive waste 27.03 X 10 1 kg (2.2 lb) of coal ash 5.41 X 10 1 kg (2.2 lb) of granite... -
Page 29: Ionizing Radiation
Model 12SA Survey Meter Technical Manual Section 9 Ionizing Radiation Here we are concerned mainly with ionizing radiation from the atomic nucleus. It occurs in two forms – rays and particles – at the high frequency end of the energy spectrum. -
Page 30: Measuring Ionizing Radiation
Model 12SA Survey Meter Technical Manual Section 9 their relatively large size, alpha particles collide readily with matter and lose their energy quickly. They, therefore, have little penetrating power and can be stopped by the first layer of skin or a sheet of paper. -
Page 31: What Are The Health Risks From Ionizing Radiation
Model 12SA Survey Meter Technical Manual Section 9 The amount of ionizing radiation, or 'dose', received by a person is measured in terms of the energy absorbed in the body tissue, and is expressed in RAD. One rad is 0.01 joules deposited per kilogram of mass. -
Page 32: How Much Ionizing Radiation Is Dangerous
Model 12SA Survey Meter Technical Manual Section 9 On the other hand, large doses of radiation directed specifically at a tumor are used in radiation therapy to kill cancerous cells, and thereby often save lives (usually in conjunction with chemotherapy or surgery). Much larger doses are used to kill harmful bacteria in food, and to sterilize bandages and other medical equipment. - Page 33 Model 12SA Survey Meter Technical Manual Section 9 2 rem/yr averaged over 5 years is the limit for radiological personnel such as employees in the nuclear industry, uranium or mineral sands miners, and hospital workers (who are all closely monitored).
- Page 34 Model 12SA Survey Meter Technical Manual Section 9 where given a set population, we can estimate that about 20 percent will die from cancer, but we cannot say which individuals will die. Finally, that a conservative estimate of risk from low doses of radiation is thought to be one in which the risk is linear with dose.
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Page 35: Background Radiation
Model 12SA Survey Meter Technical Manual Section 9 You can also use the same approach to looking at risks on the job: Industry Type Est. life expectancy lost All Industries 60 days Agriculture 320 days Construction 227 days Mining and quarrying... -
Page 36: Man-Made Radiation
Model 12SA Survey Meter Technical Manual Section 9 up to a couple thousand rem. However, there is no evidence of increased cancers or other health problems arising from these high natural levels. Man-made Radiation Ionizing radiation is also generated in a range of medical, commercial, and industrial activities. -
Page 37: Standards And Regulation
Model 12SA Survey Meter Technical Manual Section 9 Standards and Regulation Much of the evidence that has led to today's standards derives from the atomic bomb survivors in 1945, which were exposed to high doses incurred in a very short time. In setting occupational risk estimates, some allowance... -
Page 38: Troubleshooting
Model 12SA Survey Meter Technical Manual Section 10 Section Troubleshooting ccasionally, you may encounter problems with your LMI instrument or detector that may be repaired or resolved in the field, saving turnaround time and expense in returning the instrument to us for repair. Toward that end, LMI electronics technicians offer the following tips for troubleshooting the most common problems. - Page 39 Model 12SA Survey Meter Technical Manual Section 10 SYMPTOM POSSIBLE SOLUTION No power (or meter Check battery contacts. Clean them does not reach with rough sandpaper or use an engraver to clean the tips. TEST BAT OK mark) (continued) Check for loose or broken wires, especially between the main board and the calibration board.
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Page 40: Troubleshooting Scintillators
Model 12SA Survey Meter Technical Manual Section 10 SYMPTOM POSSIBLE SOLUTION No Response to Substitute a “known good” detector Radiation and/or cable. Has the correct operating voltage been set? Refer to the calibration certificate or detector instruction manual correct operating voltage. - Page 41 Model 12SA Survey Meter Technical Manual Section 10 4. Check the PMT to see if the photocathode still exists. If the end of the PMT is clear (not brownish), this indicates a loss of vacuum, which will render the PMT useless.
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Page 42: Parts List
Model 12SA Survey Meter Technical Manual Section 11 Section Parts List Reference Description Part Number Model 12SA UNIT Completely Assembled Survey Meter Model 12SA Survey Meter 48-2621 BOARD Completely Assembled Main Board, Circuit Board 5464-649 Drawing 464 x 649 0.0047µF, 3KV... - Page 43 Model 12SA Survey Meter Technical Manual Section 11 Reference Description Part Number C178 0.1µF, 100V 04-5521 C179 0.01µF, 100V 04-5523 2N3904G 05-5755 TRANSISTORS 2N0422BU 05-5763 2N3904G 05-5755 2N3904G 05-5755 Q145 MPSW51AG 05-5765 INTEGRATED CMXT3904TRLF 05-5890 CIRCUITS TLC372 06-6265 CD4098 06-6066...
- Page 44 Model 12SA Survey Meter Technical Manual Section 11 Reference Description Part Number 82K, 1/4W, 5% 10-7022 33K, 1/4W, 5% 10-7019 10 OHM, 1/4W, 5% 10-7004 2.2K, 1/4W, 5% 10-7012 22K, 1/4W, 5% 10-7070 100K, 1/4W, 5% 10-7023 10K, 1/4W, 5%...
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Page 45: Calibration Board, Drawing 363 × 665
Model 12SA Survey Meter Technical Manual Section 11 Reference Description Part Number Calibration Board, BOARD Completely Assembled Drawing 363 × 665 Calibration Board 5363-821 CAPACITORS 0.047µF, 100V 04-5565 0.0047µF, 100V 04-5570 1M, ×0.1, M 192/193 ×1 09-6814 POTENTIOMETERS 1M, ×1, M 192/193 ×10 09-6814 100K, ×100, M 192/193 ×1000... - Page 46 Model 12SA Survey Meter Technical Manual Section 11 Reference Description Part Number PORTABLE BATTERY NEGATIVE CONTACT ASSEMBLY 2001-065 PORTABLE BATTERY POSITIVE CONTACT ASSEMBLY 2001-066 CASTING Model 12SA 9363-816 PORTABLE DEEP CAN ASSY (MTA) 4363-615 MAIN HARNESS Model 12SA 8363-822 PORTABLE DEEP CAN ASSY. 4363-615...
- Page 47 Model 12SA Survey Meter Technical Manual Section 12 Section Drawings Model Board, Drawing 464 × 649 Model Board Component Layouts, Drawings 464 × 652 (2 sheets) Calibration Board, Drawing 363 × 665 Calibration Board Component Layout, Drawing 363 × 686 (2 sheets) Wiring Diagram, Drawing 464 ×...
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