Model GX-2001 Operator’s Manual
Calibration • 24
Calibration
This section covers the calibration of the Model GX-2001. Setting the zero
reading is described first followed by single calibration and auto calibration.
For single calibration, you are told what is needed to complete the task,
how to assemble the calibration kit, and how to set the span readings of the
four target gasses. The same topics are covered for auto calibration.
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.
CAUTION: BEFORE EACH DAY’S USAGE SENSITIVITY MUST BE
TESTED ON A KNOWN CONCENTRATION OF THE
COMBUSTIBLE TARGET GAS, TYPICALLY METHANE,
EQUIVALENT TO 25 - 50% OF FULL SCALE
CONCENTRATION. ACCURACY MUST BE WITHIN
-0 - + 20% OF ACTUAL. ACCURACY MAY BE CORRECTED
BY FOLLOWING THE CALIBRATION INSTRUCTIONS FOR
THE COMBUSTIBLE CHANNEL BELOW.
If the combustible channel passes the above response test and does not
require calibration, the unit should still be calibrated periodically. The
optimum frequency of calibration depends heavily on how the GX-2001 is
used. For example, instruments used daily may need to be calibrated
weekly or monthly, while instruments that are used only a few times a year
may need to be calibrated before each use. Typical calibration frequencies
range from monthly to quarterly. Make sure to perform the combustible
channel response test as described above and make sure to develop a
calibration schedule tailored to your application that takes this test and
required calibration resulting from this test into account.
Setting the Zero Readings for All Target Gasses
Whether you will calibrate the Model GX-2001 using single calibration or
auto calibration, you will need to set the zero readings first before setting
the span readings for each gas.
1. Find a fresh-air environment. This is an environment free of toxic or
combustible gasses and of normal oxygen content (20.9%).
2. Turn on the Model GX-2001 by pressing and holding the MODE/
POWER button for one second.
3. Press and hold the AIR button for about three seconds to allow the
Model GX-2001 to set the zero reading for HC, CO, and H
2
S and to set
the span for O
2
.