RKI Instruments GasWatch 2 Manual - Manual (Page 27)

GasWatch 2 Operator’s Manual Calibration • 22
NOTE: On the GW-2X, instead of 100% nitrogen (0% oxygen), it is
allowable to use an oxygen concentration of up to 19.5% to set
the zero reading.
• To carry out the calibration, you will need a fixed-flow regulator with an
on/off knob and a flow rate of 0.5 LPM (liters per minute), non-
absorbent tubing, and the calibration adapter that will fit over the
GasWatch 2’s sensor.
Assembling the Calibration Kit
WARNING: Calibrate the GasWatch 2 in a non-hazardous
environment.
1. Attach the calibration adapter to the unit. It opens up like a clothes pin
and fits over the sensor area and retains itself over the sensor.
2. Attach the calibration tubing to the calibration adapter, then attach the
opposite end of the tubing to the regulator.
Setting the Span Readings for the Target Gas
1. Make sure you have set the fresh air reading and have set up the
calibration kit as described in the procedure above.
2. Make sure the GasWatch 2 is off.
3. Press and hold the AIR button, then press and hold the POWER/MODE
button. Release both buttons when you hear a “beep.” The unit is in
calibration mode and the LCD displays “CAL” in the lower left and the
battery level in the upper right. It also displays the gas concentration the
unit expects you to use, the calibration value, when setting the span or
zero reading.
4. If necessary, use the AIR button to adjust the calibration value to the
desired setting. The calibration value must match the gas concentration
in the calibration cylinder.
5. Press the POWER/MODE button to accept the calibration value and
proceed to the calibration screen. The current gas reading is displayed.
6. Attach the regulator to the gas cylinder.
7. Turn the regulator knob counterclockwise to open the regulator.
NOTE: If you wish to cancel the span or zero adjustment process, press
and hold the AIR button for about 3 seconds. The unit will cancel
the span or zero adjustment and begin its startup sequence.