RKI Instruments GX-2012 - Preparing for Calibration or Bump Testing

162 • Preparing for Calibration or Bump Testing GX-2012 Operator’s Manual
To calibrate or bump test the GX-2012, you will need:
• Known calibrating samples of the gases being detected. The combustible
and toxic gas samples should have concentrations in approximately the
middle of the range of detection. An oxygen-free source, such as 100%
nitrogen is recommended for setting the oxygen zero when using single
calibration.
WARNING: When using auto calibration, the multi-gas cylinder must
have an oxygen concentration in the range of 10% - 18%
oxygen.
• A gas collection bag with hose clamp
• A 0.5 LPM fixed-flow regulator or dispensing valve
• Non-absorbent tubing
To calibrate the %LEL, Oxygen, CO, and H
2
S sensors at the same time,
automatically, with no need for a zero-oxygen source, you can use the auto
calibration feature with a 4-gas cylinder. If the H
2
S channel is not active, then
a 3-gas cylinder may be used for auto calibration. This appendix includes
instructions for auto calibration with a fixed flow regulator or dispensing
valve, a 4-gas cylinder, and a %volume methane cylinder. This document
also includes instructions for calibrating one channel at a time using single
calibration.
NOTE: If the combustible gas channel(s) are calibrated to a gas other
than methane, use an appropriate multigas cylinder or use
single calibration to calibrate the combustible channel(s).
Preparing for Calibration or
Bump Testing
Whether you will calibrate the GX-2012 using auto calibration or single
calibration, or perform a bump test, you will need to set the fresh air 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 gases and of normal oxygen content (20.9%).
2. Turn on the unit as described in “Turning On the GX-2012, Normal Mode
Only” on page 19 using the sample hose and probe.
3. With the unit on, perform a fresh air adjustment by pressing and holding
the AIRS button. The display prompts you to hold the AIRS button.