RKI Instruments 35-3010RK-04 - Manual (Page 21)

35-3010RK-04 Sample-Draw Detector • 17
If the sample draw detector goes into low flow alarm before you can adjust the flow
down to 0.6 SCFH, adjust the low flow potentiometer 1/4 turn clockwise, then
attempt to set the flow again. Repeat this step until you are able to adjust the flow to
0.6 SCFH.
2. Slowly turn the low flow potentiometer counterclockwise just until the sample draw
detector goes into low flow alarm.
NOTE: The low flow potentiometer is accessible through a circular cutout in the main
circuit board. The cutout is labeled PS1.
3. Verify that the low flow alarm is 0.6 SCFH (±0.2). Repeat steps 3 and 4 if necessary.
4. Use the flow adjust potentiometer (VR1) to set the flow to 1.2 SCFH.
5. Make sure the sample draw detector’s Fail light is off.
Calibration Frequency
Although there is no particular calibration frequency that is correct for all applications, a
calibration frequency of every 3 months is adequate for most sample draw detector
applications. Unless experience in a particular application dictates otherwise, RKI
Instruments, Inc. recommends a calibration frequency of every 3 months for the sample
draw detector.
If an application is not very demanding, for example detection in a clean, temperature
controlled environment, and calibration adjustments are minimal at calibration, then a
calibration frequency of every 6 months is adequate for the sample draw detector.
If the application is very demanding, for example if the environment is not well
controlled, then more frequent calibration than every 3 months may be necessary for the
sample draw detector.
Calibration, LEL Detector
This section describes how to calibrate the LEL sensor in the sample draw detector. It
includes procedures to set the zero reading, set the response reading, and return to normal
operation.
NOTE: This procedure describes calibration using a demand flow regulator, a zero air
calibration cylinder, and a 3-gas calibration cylinder.
Setting the Zero Reading
NOTE: If you can verify a fresh air environment, it is not necessary to use the zero air
calibration cylinder to set the zero reading.
1. Open the housing door.
2. Screw the regulator into the zero air calibration cylinder.
3. Connect the calibration kit sample tubing to the regulator.
4. The zero reading for the LEL channel is set at the controller. See the controller
operator’s manual for instructions to set the zero reading.