18 • 65-2405RK-05-04 Combustible Gas Transmitter
Calibration Frequency
Although there is no particular calibration frequency that is correct for all applications, a calibration
frequency of every 3 to 6 months is adequate for most combustible gas transmitter 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 where combustible gas is not normally present 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 combustible gas is present often and in significant
concentrations or the environment is not well controlled, then more frequent calibration than every 3
months may be necessary. If potential catalyst poisons are known or likely to be present, more frequent
calibration than every 3 months will be necessary.
Determining Response Time
Since the detector junction box is installed remotely from the amplifier, the response time of the
detector will depend on the length of flexible tubing that is attached to the calibration cup/splash guard.
To determine the response time based on the length of tubing connected:
1. Place the controller into its calibration mode or disable external alarms.
2. Note the current gas reading displayed at the controller.
3. Screw the regulator into the calibration cylinder. Do not use a zero air cylinder for this operation.
4. Use the flexible tubing coming from the calibration cup/splash guard to connect the regulator to
the calibration cup.
5. Turn the regulator’s on/off knob counterclockwise to open the regulator. Gas will begin to flow.
Take note of the time or start a stopwatch.
6. When you first start to notice an increase in the gas reading, note how much time passed between
starting the gas flow and noticing a reading response.
7. Turn the regulator’s on/off knob clockwise to close the regulator.
8. Unscrew the regulator from the calibration cylinder.
9. Disconnect the calibration cup/splash guard’s flexible tubing from the regulator.
NOTE:
Do not disconnect the flexible tubing from the calibration cup/splash guard.
10. Add 1 minute to the length of time determined in Step 6. This is the response time for the detector.
When performing a response test, zero adjustment, or span adjustment, gas must be applied for this
length of time.
