RKI Instruments GasWatch 1 - Manual (Page 13)

GasWatch Instruction Manual (Two-Gas) Calibration • 9
Calibration
This section describes how to prepare for calibration, calibrate the GasWatch, and return
to normal operation. This section also describes equipment that is necessary to perform
the calibration procedure.
Supplies and Equipment
To calibrate the GasWatch, you will need the following supplies and equipment. RKI
calibration kits are available for this purpose (see “Parts List” on page 14).
• For the toxic gas sensor (CO or H
2
S), known calibrating samples of the target gas. The
samples should have concentrations in approximately the middle of the range of
detection.
• For the oxygen sensor, an oxygen-free source, such as pure nitrogen or CO in a
nitrogen balance
• A fixed-flow regulator, non-absorbent tubing, and calibration cup
Assembling the Calibration Kit
WARNING: Calibrate the GasWatch in a non-hazardous environment.
1. Attach the calibration tubing to the calibration cup, then attach the opposite end of the
tubing to the regulator.
2. Slide the calibration cup over the toxic gas (CO or H
2
S) sensor.
NOTE: Do not attach the regulator to the gas cylinder at this time.
Calibrating the GasWatch
This section describes calibration of the toxic gas and oxygen sensors.
Calibrating the toxic gas sensor
1. Verify that the GasWatch is turned off.
Only the time of day is displayed when the GasWatch is off. To turn off the GasWatch,
press the POWER button until only the time of day is displayed (approximately 5
seconds).
2. Press and hold the AIR and MODE buttons simultaneously until the GasWatch beeps
and CAL displays (approximately 2 seconds).
The toxic gas calibration screen automatically displays.
3. Attach the regulator to the toxic gas cylinder. The fixed-flow regulator automatically
begins introducing the calibration sample to the toxic gas sensor.