RKI Instruments Digester Gas Monitor User Manual
Page 89
Digester Gas Monitor Operator’s Manual
Sensor Replacement • 83
9.
Reinstall the preamp circuit board with the sensor onto the flow block.
10. Turn the regulator knob clockwise to set the sensor flow to 3 SCFH when you restart
the system.
11. Turn on incoming power.
12. Calibrate the replacement sensor as described in “Performing a Calibration” on
page 63.
Replacing the Oxygen Sensor
1.
Turn off the Digester Gas Monitor.
2.
Turn off incoming power to the Digester Gas Monitor.
3.
Open the housing door of the Digester Gas Monitor.
4.
Turn the regulator knob all the way counterclockwise to close the regulator output.
5.
The oxygen sensor is located in the upper right corner of the flow block when viewed
from the top. Unscrew the two screws that hold the oxygen sensor bracket a few turns
so that you can rotate and remove the oxygen sensor bracket.
There is an O-ring located in the bottom of the sensor cavity. Make sure the O-ring
stays in place.
6.
Unplug the connector from the socket that leads from the sensor.
7.
Plug the socket of the replacement sensor into the connector.
8.
Place the sensor in the oxygen sensor cavity of the flow block, then position the
retaining plate on the two standoffs.
9.
Reinstall the oxygen sensor bracket and tighten both bracket screws firmly.
10. Turn the regulator knob clockwise to set the sensor flow to 3 SCFH when you restart
the system.
11. Turn on incoming power.
12. Calibrate the replacement sensor as described in “Performing a Calibration” on
page 63.
Replacing the H
2
S Sensor
1.
Turn off the Digester Gas Monitor.
2.
Turn off incoming power to the Digester Gas Monitor.
3.
Open the housing door of the Digester Gas Monitor.
4.
Turn the regulator knob all the way counterclockwise to close the regulator output.
5.
The H
2
S sensor and preamp are located in the bottom left corner of the flow block
when viewed from the top. Unscrew the 2 screws that retain the preamp circuit board.
Take care not to lose the flat washer and lock washer under each screw head.
6.
Lift the preamp circuit board away from the flow block.
Be careful not to pull on the cable that connects the preamp circuit to the main circuit
board.
There is a gasket in the bottom of the sensor cavity. Make sure the gasket stays in
place.
7.
Pull the H
2
S sensor off the preamp circuit board.
8.
Plug the new sensor into the preamp board.