Ludlum 2241-2RKFamiliarization and Operation

Ludlum 2241-2 Response Kit

• Contains:– 2241-2 and check source– 44-2 gamma probe– 44-9 pancake probe– Cable, batteries– Manuals

                                          

Ludlum 2241-2• The Model 2241-2 is a portable

microprocessor-based digital Scaler/Ratemeter designed for use with a variety of detector types for measurement of ionizing radiation. 

• Side mounted check source

Model 44-2 Gamma Probe

• Very sensitive to Gamma radiation

• Uses a 1”x1” crystal (NaI)

• Not rugged – but Not delicate

• Intended to search for radiation

Model 44-9  (Pancake) Probe

• Detects Alpha, Beta, Gamma, & X-ray

• Gas Tube covered by thin Mica window

• For use when surveying for contamination

Accessories

• Cable

• Batteries (may be removed for storage)

• Manuals

• Case

Ludlum 2241-2

• 3 position selector switch– Off/Ratemeter/Scaler

• Locking toggle probe switch• Audio on/off switch• Fast/Slow response switch• Light button• Reset button

2241-2 Display• LCD 4-Digit display

• Floating decimal point

• Auto ranging from uR/hr to mR/hr to R/hr

(KCpm to Cpm as well)

2241-2 Display (cont)

• Overflow – “OFLOW” indicates the incoming count of exposure exceeds the capability to display stable or reliable readings.

• Alert – shows at 20 KCpm or 20 uR/hr• Alarm – shows and sounds at 50 KCpm or 50

uR/hr

2241-2 Display (cont)

• Overload – Indicates the detector is being exposed to radiation intensities greater than the detector maximum operating limit, and/or the mica window has been damaged.

• Counting – Indicates the Scaler count switch has been depressed and the Scaler is accumulating counts for the pre-determined count time.

Operating Instructions• Safety – Always switch into “OFF” position before

connecting or disconnecting the cable or detector.

• Install Batteries - Open the battery lid and install two "D" size batteries.  Note (+) (-) marks on the inside of the lid.  Match the battery polarity to these marks.  Close the battery box lid.

• Connecting Probes – Select “Det 1” or “Det 2”. Connect the probe (Det 1 = 44-9, Det 2 = 44-2 they are color coded as well). Connect one end of the cable provided to the detector by firmly pushing the connectors together while twisting clockwise ¼ turn until it latches

Operating Instructions (cont)

• Place Audio switch into off position

• Place F/S switch into Fast position

• Double check your detector switch position

Operating Instructions (cont)• Power on – Turn selector switch clockwise to ‘Ratemeter”

setting. The meter will cycle through its startup routine and display will show – All indications– Program version– Detector channel selected– Go to Ratemeter mode

Operating Instructions (cont)• Battery low indication will blink if batteries are low.

• Operational check – Place gamma probe/pancake probe directly on the check source and observe readings greater than 250 uR/hr. You can also check the calibration readings on the calibration record.

Operating Instructions (cont)• Check the unit’s response:

– Place the probe next to the source – the indications should increase and stabilize– Pull the probe away from the source and the indications should decrease, slowly return to the

source and the indications should rise up again.– Place the F/S switch to SLOW. Remove and replace the probe. Response times should be

significantly slower.

• Place the audio switch into the ON position – the audible should corresponded to the display readings.

• The unit is ready for use.

Scaler Operations• The 2241-2 has a Scaler function to assist in detecting

low levels of radiation.

• Operating in the Scaler mode.– Place audio in the OFF position– Place the OFF/Ratemeter/Scaler 3 position switch in the

SCALER position.– Place the probe face close to the item to be counted (both probes

44-2 and 44-9 can be in Scaler mode)– Press the Scaler start button in the handle. The word “Counting”

will appear in the display.

Scaler Operations (Cont)• Operating in the Scaler mode (Continued).

– The 2241-2 will begin a 12 second count cycle. – At the end of the 12 seconds the word Counting will disappear

and the total for the count will be displayed.

• Place the OFF/Ratemeter/Scaler 3 position switch in the Ratemeter position to begin surveys again.

Alert and Alarm• When the probe detects radiation in levels that exceed the alert level the

word ALERT will appear in the screen.– Remove the probe from near the radiation and press the reset button. The count will

reset to zero and the Alert will go away

• When indications exceed the alarm level the word ALARM will appear in the window and an audible alert will sound– Remove the unit from near the source and press reset once. This will quiet the

audible alarm. Note: the alarm will sound even if the speaker is turned off.– Press the reset a second time and it will reset the count and ALARM will go away.

Using the Ludlum 2241• Take a background reading before surveying for radiation

• Three times above background is radiation

• With the 44-2 Gamma probe use a “Stately Pace” and point the detector at the area to survey

• With the 44-9 use the red plastic cover to protect the mica surface. You can also use it when you use the 44-9 for gamma surveys. (alphas and betas will be blocked)

Using the Ludlum 2241 (cont)• Place the 44-9 pancake head about ¼ to ½ an

inch above the surface surveyed.

• Survey at 1 inch per second with the 44-9

Be careful when handling the connector cable as it can provide an uncomfortable shock.

Using the Ludlum 2241 (cont)• The audio on position consumes batteries faster

than when set to off

• Use the Fast position for general surveys and the Slow position for low level surveys

Recommendations• DO NOT leave the batteries in the unit if you do not

intend to use it.• Give the unit 5-10 seconds to stabilize once you

have turned it on.• Do not get water on the mica window. Wrap it in a

plastic bag (for gammas) Also works to prevent contamination.

• Store where you would be comfortable, no temperature extremes

Questions

Contact Info

Bill Potter

Governor’s Office of Emergency Services

Radiological Preparedness Unit

(916) 845-8755

Bill.potter@oes.ca.gov