100 • Using Maintenance Mode
GX-2012 Operator’s Manual
Calibrating Using Single Calibration
If
CL EXPRD
is set to
NOT USE
and calibration becomes due, then the unit must be
calibrated using this menu item and/or the previous menu item,
AUTO CAL
because it
will not be possible to enter normal operation. See “Calibration/Bump Test Supplies and
Equipment” on page 56 for the items you will need to perform a calibration.
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. Perform a fresh air adjust. See “Performing a Fresh Air Adjustment” on page 96 for
instructions.
2. Install the demand flow regulator onto the calibration cylinder.
3. Connect the sample tubing to the demand flow regulator.
4. Install the hose and probe to the GX-2012.
5. Use the AIR
or (SHIFT)
buttons to scroll to the
ONE CAL
menu option.
MAINTENANCE
ONE CAL
www.calcert.com
1.800.544.2843
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