RKI Instruments 35-3000RKA-10 - Manual (Page 21)

35-3000RK-10 PPM Hexane Sample Draw Detector • 21
5. Use the flow adjust pot (VR1) to set the flow to 1.5 SCFH.
6. Make sure the sample draw detector’s Fail LED is off.
Setting the Detector Load Voltage
The detector load voltage must be set when the detector or amplifier is replaced or if you
suspect that it has been changed from the factory setting for your detection range. This
procedure involves setting a voltage while applying calibration gas to the sample draw
detector that matches the full-scale concentration for the sample draw detector. After
replacing the detector or amplifier as described earlier in this manual, the following
procedure must be completed before calibrating the sample draw detector. Be sure to
follow the timing recommendations in “Replacing the Detector” on page 17 and
“Replacing the Amplifier” on page 18 for setting the load voltage.
NOTE: Setting the load voltage may cause alarms. Be sure to put the controller into
calibration mode or disable external alarms before performing this test.
WARNING: The controller is not an active gas monitoring device during the load
voltage setting procedure
NOTE: The following procedure assumes the use of a calibration kit that includes a
calibration gas cylinder equal to the transmitter’s full scale gas concentration, a
dispensing valve with an on/off knob, a gas bag, and a humidifier tube to
connect the gas bag to the regulator and to the sample draw detector inlet line.
NOTE: For best accuracy, RKI Instruments, Inc. recommends introducing the gas at the
end of the inlet sample line when making a load voltage adjustment instead of
using a temporary short sample line.
1. Put the controller into calibration mode or disable external alarms.
2. Open the sample draw detector housing door.
3. Set a voltmeter to measure in the DC millivolt range.
4. Remove the screw, flat washer, and lock washer retaining the amplifier plate to each
of the two mounting standoffs, then carefully lift the amplifier plate to gain access to
the amplifier’s load voltage adjustment pot. See Figure 5 below for the pot location.
5. Screw the dispensing valve onto the calibration gas cylinder. It must have a gas
concentration equal to the sample draw detector’s full scale.
6. Run one end of the humidifier tube through the tubing clamp provided with the
calibration kit and connect this end to the fitting on the gas collection bag.
WARNING: The humidifier tube used with this calibration kit includes polyurethane
tubing on each end of the humidifier tube to facilitate making connections
to hose barbs. Do not clamp on the middle braided tube section of the
humidifier tube. Only clamp on the polyurethane tube on either end of the
braided humidifier tube.