RKI Instruments GD-K7D2 (24 VDC) - Manual (Page 24)

20 • Model GD-K7D2 (24 VDC) Sample Draw Transmitter
calibration frequency of every 6 months is adequate.
If an application is very demanding, for example if the environment is not well controlled,
then more frequent calibration than every 3 months may be necessary.
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