18 • 35-3001-01H-DIL Hydrogen Sample-Draw Detector
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.
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 hydrogen sensor of 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:
When calibrating the LEL sensor, if an inlet sample line is installed, calibration gas must
be applied at the end of the inlet line, not at the inlet fitting. The calibration will not be
accurate if calibration gas is applied at the inlet fitting.
Preparing for Calibration
1. Follow the instructions in the controller’s operator’s manual for entering calibration mode.
NOTE:
If you can verify a fresh air environment, it is not necessary to use the zero air calibration
cylinder to set the zero reading.
2. Screw the fixed flow regulator into a zero air calibration cylinder.
Setting the Zero Reading
1. Attach the gas bag tubing to the regulator on the zero air calibration cylinder.
NOTE:
A demand flow regulator cannot be used for calibration.
2. Turn the regulator’s on/off knob clockwise to open it. Fill the gas bag.
3. Turn the regulator’s on/off knob counterclockwise to close it.
4. Clamp the gas bag shut and disconnect it from the fixed flow regulator.
5. Connect the gas bag tubing to the inlet line and release the clamp.
6. Allow the sample-draw detector to draw sample for one minute.
7. Follow the directions in the controller’s operator’s manual for setting the zero reading. If you
used a zero air calibration cylinder to set the zero reading, proceed to step 9. If you verified a
fresh air environment, proceed to the next section, Setting the Response Reading.
8. Disconnect the gas bag tubing from the inlet line.
9. Empty the gas bag.
