154 • Calibrating the GX-2012
GX-2012 Operator’s Manual
17. If you have a 5 sensor unit and wish to calibration the %volume combustible gas
sensor, go back to step 1 and repeat the process, selecting the %volume calibration
gas value screen in step 12 and using a %volume methane cylinder to fill your gas
bag.
If you are finished calibrating, use the (SHIFT)
button to navigate to the
NORMAL
menu item, then press and release the POWER ENTER button to return to
Measuring Mode.
Calibrating with the Single Calibration Method
This section describes calibration using the Single Calibration method.
To calibrate using the Auto Calibration method, see “Calibrating with the Auto
Calibration Method” on page 151.
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, and non-
absorbent sample tubing. The standard 4-gas cylinder consists of 50% LEL methane, 12%
oxygen, 50 ppm CO, 25 ppm H
2
S, and a balance of nitrogen. In the example below, the
CH
4
channel’s span is adjusted. See “Parts List” on page 145 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, use
an appropriate gas cylinder to perform the calibration.
CAUTION:
The single calibration method does not have a “FAIL” notification. If a
sensor cannot be set to agree with the calibration source, see
“Troubleshooting” on page 131.
1. While in the calibration menu, use the AIR
or (SHIFT)
button to the ONE CAL
menu option.
MAINTENANCE
ONE CAL
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