RKI Instruments 35-3001-09 - Manual (Page 22)

18 • 35-3001-09 Oxygen/Hydrogen Sulfide Sample-Draw Detector
3. Install the new filter. Be sure the side of the filter marked “INLET” is connected to the elbow
that is connected to the inlet fitting.
4. Verify that the flow rate is approximately 1.0 SCFH, then close the housing door.
Replacing the Particle Filter
1. Disconnect the tubing routed to the sampling area, if installed, from the particle filter.
2. Disconnect the particle filter from the inlet fitting’s tubing stub.
3. Install the new particle filter onto the inlet fitting’s tubing stub. Be sure the arrow on the
particle filter is pointing toward the inlet fitting.
4. Reinstall the tubing routed to the sampling area.
Adjusting the Low Flow Setting
NOTE: Adjusting the low flow setting will cause a low flow alarm at the sample-draw detector
and a fail alarm at the controller. Be sure to put the controller into its calibration program
or disable external alarms before performing this test.
The factory-set low flow setting is 0.6 SCFH (±0.1). To adjust the low flow setting:
1. Use the sensor flow control valve to set the flow to 0.6 SCFH. Turn the valve’s knob clockwise
to increase the flow and counterclockwise to decrease the flow.
If the sample-draw detector goes into low flow alarm before you can adjust the flow down to
0.6 SCFH, adjust the pressure switch adjustment screw 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.
NOTE: The pressure switch adjustment screw is accessible through a circular cutout in the
flowmeter circuit board.
2. Slowly turn the pressure switch adjustment screw counterclockwise just until the sample-draw
detector goes into low flow alarm.
3. Turn the sensor flow control valve’s knob clockwise to increase the flow until the unit is out of
low flow alarm.
4. Decrease the flow very slowly by turning the sensor flow control valve’s knob
counterclockwise and verify that the low flow alarm is 0.6 SCFH (±0.1).
If the low flow alarm is set too low, turn the pressure switch adjustment screw slightly
clockwise. Repeat steps 3 and 4 if necessary.
5. Use the sensor flow control valve to set the flow to 1.0 SCFH.
6. Make sure the sample-draw detector’s Fail LED 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.
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.