RKI Instruments Digester Gas Monitor - Manual (Page 70)

64 • Performing a Calibration Digester Gas Monitor Operator’s Manual
Performing a Fresh Air Adjustment
Performing a fresh air adjustment sets the gas reading in fresh air for the selected
channels to zero for all channel types except oxygen. The oxygen channel is set to 20.9%
in fresh air.
To perform a fresh air adjustment for the selected channels, do the following:
1. Navigate to the Select Operation Screen as described in “Entering Calibration Mode”
on page 62.
2. Use the UP/YES or DOWN/NO button to display PERFORM AIR ADJUST on the
Select Operation Screen.
3. Press and release the ENTER button. The Select Channel(s) screen appears.
4. Use the UP/YES or DOWN/NO button to scroll through the channel combination
choices and select the channel or channels that you will air adjust.
5. Press and release the ENTER button to accept the displayed choice and continue
with the air adjustment. The Digester Gas Monitor will begin to draw sample through
the Fresh Air Inlet. The display will alternate between the two screens shown below. In
the example below, channels 1, 2, and 3 have been selected for an air adjust.
6. Confirm that the tubing installed at the Fresh Air Inlet fitting is routed to a fresh air
area.
7. If necessary, adjust the flow rates as described in “Adjusting the Flow Rates” on
page 33 before continuing. The flow rate must be set to 3 SCFH for channels 1, 2, and
3 or per Table 5 for channel 4 (H
2
S).
8. Allow the Digester to draw fresh air for 1 minute.
9. Press and release the ENTER button. For methane, oxygen, and carbon dioxide
channels, the solenoids will click and the flow to the sensors will be stopped for 15
seconds to allow for a stabilization period. The hydrogen sulfide channel does not
need a stabilization period.
10. The Digester Gas Monitor will perform a fresh air adjustment and the display will
indicate AIR ADJUST PASSED for each detector if the air adjust is successful. If the
air adjust was not successful for any channel, the display will indicate AIR ADJUST
FAILED for that channel. The Digester Gas Monitor will then return to the Select
Operation screen.
Select Operation
PERFORM AIR ADJUST
UP / DN then ENT / ESC
Select Channel(s)
For FRESH AIR Adjust
1
UP / DN then ENT / ESC
Apply FRESH AIR
To Gas Detectors
- > ENTER when Done
- > ESCAPE to Abort 1: METHANE 0 %VOL
2: OXYGEN 20.9 %VOL
3: CO2 0.0 %VOL