RKI Instruments GX-86 User Manual

Page 14

10 • Calibration

Model GX-86 Instruction Manual

NOTE: The combustibles measurement is flow-sensitive. If you are using a dispensing

valve instead of a regulator, use a flowmeter and set the flow rate to 1.0 SCFH
(approximately 0.5 LPM).

6. Watch the GX-86 display to verify the combustibles reading matches the

concentration of the calibrating sample. If the reading does not correspond with the
sample, slowly adjust the COMB SPAN control.

7. Expose the sensor to fresh air and verify that the combustibles reading returns to zero.

8. Repeat the exposure to the calibrating sample and verify that the combustibles

reading reaches the correct level. Repeat steps 5 through 8 until no further adjustment
is required.

NOTE: If the combustibles reading cannot be set high enough to agree with the

calibrating sample, replace the sensor.

Calibrating the oxygen channel

1. Use a calibration cup and gas cylinder to expose the oxygen sensor to a know oxygen-

free sample, such as 100% nitrogen (available from RKI).

2. Watch the display to verify that the O

reading decreases to 0.0. If the reading does not

reach 0.0, adjust the O

ZERO control.

NOTE: Replace the oxygen sensor if the you cannot adjust the oxygen reading to 0.0.

Replace the oxygen sensor if you cannot adjust the oxygen reading to 20.9% with
the auto zeroing featuring the next time the GX-86 is turned on.

Calibrating the H

S and CO channels

The H

S and CO circuits use the same procedure for span adjustment. Follow these steps

using the appropriate calibrating sample for the corresponding sensor.

1. Use a calibration cup and gas cylinder to expose the sensor to a calibrating gas

sample. The sample should represent the target gas at a midrange concentration. (The
RKI Calibration Kit is ideal for this application. See kit instructions for assembly and
use.)

2. Watch the display to verify the reading agrees with the concentration in the

calibrating sample. If not, adjust the corresponding control (H

S or CO SPAN).

NOTE: If the reading cannot be set high enough to agree with the calibrating sample,

replace the sensor.