RKI Instruments GasWatch 2 Manual - Manual (Page 26)

21 • Calibration GasWatch 2 Operator’s Manual
Calibration
This section covers the calibration of the GasWatch 2. Setting the fresh air
reading is described first followed by setting the span (GW-2C and GW-2H)
and zero (GW-2X) reading. You are told what is needed to complete the
task, how to assemble the calibration kit, and how to set the span (zero for
GW-2X) reading.
WARNING: Use a 0.5 LPM (liters per minute) fixed flow regulator
when calibrating. Use of a different flow rate may
adversely affect the accuracy of the calibration.
Setting the Fresh Air Reading
You will need to set the fresh air reading first before setting the span (zero
for GW-2X) reading.
1. Find a fresh-air environment. This is an environment free of toxic or
combustible gases and of normal oxygen content (20.9%).
2. Turn on the GasWatch 2 by pressing and holding the POWER/MODE
button for one second. Allow the unit to finish its warm-up sequence.
3. Press and hold the AIR button for about three seconds to allow the
GasWatch 2 to set the fresh air reading. It will set the reading on the
GW-2C and GW-2H to 0 ppm and on the GW-2X it will set the reading
to 20.9% oxygen.
4. While you are pressing the AIR button, the LCD displays “Hold”, a
prompt for you to keep pressing the AIR button.
5. When the fresh air reading has been set, the LCD displays “Adj”, which
prompts you to release the AIR button.
Setting the Span (Zero for GW-2X) Reading
This section tells you how to set the span reading on the GW-2C and GW-
2H and the zero reading on the GW-2X using the Calibration Mode.
Preparation
Set the fresh air reading as described in “Setting the Fresh Air Reading.”
You will also need the supplies listed below. A calibration kit is available
from RKI Instruments, Inc. for each GasWatch 2 model for this purpose
(see “Parts List”).
• A gas cylinder with an appropriate concentration of the target gas for
the GW-2C or GW-2H, or a cylinder of 100% nitrogen for the GW-2X.