RKI Instruments GD-K7D2 (115 VAC) - Manual (Page 24)

20 • Model GD-K7D2 (115 VAC) Sample Draw Transmitter
Calibration
This section describes how to calibrate the GD-K7D2. It includes procedures to prepare for
calibration, set the zero reading, set the response reading, and return to normal operation.
Preparing for Calibration
NOTE: This procedure describes calibration using the RKI calibration kit that incudes a
“demand flow” regulator. A calibration kit that uses a gas collection bag is also
available. Contact RKI Instruments, Inc. for more information concerning the gas
collection bag accessory.
1. Put the controller into its calibration program or disable external alarms to avoid
unwanted alarms during calibration.
2. Screw the regulator into the zero air calibration cylinder.
NOTE: If you can verify that the GD-K7D2 is drawing sample from a fresh air
environment, you do not need to apply zero air to set the zero reading.
3. Disconnect the incoming Teflon sample tubing from the GD-K7D2’s sample filter.
4. Connect the calibration kit sample tubing to the sample filter.
NOTE: Do not connect the calibration kit sample tubing from the sample filter to the
regulator at this time.
5. Loosen the thumbscrew on the front of the cover, then remove the cover from the
detection unit and installation bracket.
6. Use small test clips to connect a milliampmeter to the output check pins.
7. Use the following formula to determine the correct GD-K7D2 (response) output for
the calibrating sample.
Response Output (mA) = (calibrating gas/fullscale) X 16 + 4
For example, if you have a cylinder of 5 ppm calibration gas with a GD-K7D2 full
scale of 10 ppm:
12 mA = (5 ppm/10 ppm) X 16 + 4
Setting the Zero Reading
1. Connect the calibration kit sample tubing from the sample filter to the regulator.
NOTE: The GD-K7D2 pump automatically begins pulling the calibrating sample from
the calibration cylinder when the calibration kit is completely assembled and
connected to the GD-K7D2’s sample filter.
2. Allow the GD-K7D2 to draw gas for two minutes and verify a reading of 4.0 mA. If
necessary, use the zero pot to adjust the reading to 4.0 mA.
3. Disconnect the calibration kit sample tubing from the regulator, then unscrew the
regulator from the zero air calibration cylinder.
Leave the calibration kit sample tubing connected to the sample filter.