Ludlum Measurements 3100, Manual, Page: 20 / 57

2-5
Figure 2-4. First Check Display Screen.
2.3.4 Instrument Test.
To assure proper operation of the instrument between calibrations and periods of non-use,
the following instrument operational check should be performed daily or prior to use. This test takes less than 60
seconds to complete.
Rotate the main rotary knob to the CHECK position. When the first screen (Figure 2-4) is shown, after the pump has
shut off (this takes about 8 seconds), press the ACK/RESET button. The second CHECK mode screen, labeled
“Check Test,” will then be shown. Two possibilities exist for this test – internal electronic-only test or external
source test. For more instructions on how to set up this function, please refer to the Model 3100 software manual.
Note: If the airflow has not reached the minimum accepted value before the ACK/RESET button is pressed, the
“Fail Air” audible alarm will turn on without the status message being displayed. Pressing the ACK/RESET button
to silence the audible alarm will exit the “Check Test” screen.
Note: If the “Check Test” value is greater than the alert or alarm values, the audible alarms will be activated without
the accompanying text being displayed.
Note: At the end of the 60 seconds, the instrument will display one of two screens, depicted in either Figure 2-5 or
2-6.
Figure 2-5. Check Test Screen Ok. Figure 2-6. Check Test Screen Fail.
a. INTERNAL-A preset bias and the resulting reading may be defined at calibration in order to give a
consistent reference reading during the CHECK operation. This reading tests the electronics and amplifier
and will generate a repeatable reading if the circuits are functioning properly. If the instrument fails to read
within 20% of a proper reading within 60 seconds, it should be sent to a calibration facility for
recalibration. See Figure 2-7 for an example of an internal test screen.