RKI Instruments GX-2012 Manual - Manual (Page 65)

GX-2012 Operator’s Manual Calibration Mode • 57
Calibration Mode
Calibration Mode allows you to calibrate the GX-2012’s sensor response and
to bump test the GX-2012.
CAUTION: BEFORE EACH DAY’S USAGE, SENSITIVITY IN THE
% LEL RANGE MUST BE TESTED ON A KNOWN
CONCENTRATION OF THE COMBUSTIBLE TARGET GAS,
METHANE, EQUIVALENT TO 25 - 50% OF FULL SCALE
CONCENTRATION (The % LEL full scale is
100% LEL). ACCURACY MUST BE WITHIN -0 to + 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-2012 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.
You can program the GX-2012 to notify you when it is due for calibration.
See “Updating the Calibration Reminder Setting” on page 130.
Calibration/Bump Test Supplies and Equipment
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.
• A demand-flow regulator to provide adequate sample gas flow
• Non-absorbent tubing