40 • Calibration Mode
GX-2009 Operator’s Manual
15. Leave the regulator connected to the calibration adapter plate for convenience.
16. Store the components of the calibration kit in a safe and convenient place.
Performing a Span Adjustment in ONE CAL
Entering the ONE CAL menu item allows you to perform a span adjustment on one channel at
a time. This feature is useful for situations when you do not need to calibrate all channels,
such as when you are replacing a sensor.
Perform a span adjustment as part of a calibration after performing a fresh air adjustment.
Performing a span adjustment requires the use of a calibration kit. The procedure below
describes a span adjustment of one channel using a calibration kit that includes a 4-gas
calibration cylinder, a 0.5 LPM (liters per minute) regulator, a calibration adapter plate, and
non-absorbent sample tubing. The standard 4-gas cylinder consists of 50% LEL methane,
12% oxygen, 25 ppm H
2
S, 50 ppm CO, and a balance of nitrogen. If the H
2
S channel on your
GX-2009 is active, then use a 4-gas cylinder so that you can calibrate all channels when
necessary. If the H
2
S channel on your GX-2009 is not active, you may use a 3-gas cylinder.
The standard 3-gas cylinder consists of 50% LEL methane, 12% oxygen, 50 ppm CO, and a
balance of nitrogen. In the example below, the CH
4
channel’s span is adjusted. See “Parts
List” on page 67 for available calibration kits and calibration kit spare parts.
Calibration cylinders that contain only one target gas may also be used for single calibration.
For channels other than oxygen, RKI Instruments, Inc. recommends that you use a cylinder
that contains a concentration of 10-50% of the full scale value of the target gas. For example,
if you are calibrating the combustible gas channel, your calibration cylinder should have a
combustible gas concentration between 10% LEL and 50% LEL. For the oxygen channel,
RKI Instruments, Inc. recommends using 100% nitrogen to perform the adjustment but any
concentration between 0% oxygen (100% nitrogen) and 17% oxygen can be used to make the
adjustment.
NOTE:
If your combustible gas channel is calibrated to a gas other than methane, such as
isobutane, use an appropriate gas cylinder to perform the calibration.
WARNING: Calibrate the GX-2009 in a non-hazardous environment.
1. Before performing a span adjustment, perform a fresh air adjustment as described in
“Performing a Fresh Air Adjustment” on page 34.
ONE CAL
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