RKI Instruments 35-3010RKA-04 - Manual (Page 23)

35-3010RKA-04 Sample-Draw Detector • 19
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 prepare for calibration, 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.
Preparing for Calibration
CAUTION: This procedure may cause alarms at the controller. Take appropriate action to avoid
this, such as entering the calibration mode at the controller.
1. Open the housing door.
2. Set a voltmeter to measure in the millivolt (mV) range.
3. Plug the voltmeter into the test points on the LEL transmitter. Plug the positive lead
into the test point labeled TP+; plug the negative lead into the test point labeled TP-.