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Chapter 4 Maintenance Series 830/840/860 Instruction Manual
4-6 IM-83/84/86-H
Sensor Maintenance
The sensor tube is straight and has a relatively large, 0.031 inch
ID, which makes inspection and cleaning easy. Sensor mainte-
nance consists of:
• inspecting and cleaning the sensor flow path
• checking the sensor for proper electrical function
Sensor Cleaning and Inspection
Cleaning is accomplished by simply rodding out the sensor with
the Sensor Cleaning Stylette, part number “CK”, available from
Sierra for this purpose. (A 0.020 inch to 0.028 inch diameter piano
wire may also be used.) To access the sensor for inspection or
cleaning:
1. Remove the unit from the system.
2. Remove the two socket head ac-
cess port plugs with a 1/4 inch
Allen wrench.
3. Visually inspect the sensing ports
and sensor.
4. Use a hemostat or tweezers to push the cleaning wire into the
downstream opening of the sensor tube. Do not force the clean-
ing wire; move it back and forth–DO NOT TWIST OR
ROTATE.
5. Flush the sensor tube with a non-residuous solvent. In cases
where solids are deposited in sensor, units should be returned
to factory for complete cleaning and re-calibration.
6. Blow dry all parts with dry nitrogen and re-assemble.
7. When the transducer is re-installed in the system, leak test the
connection.
8. Check transducer calibration.
Caution!
Do not remove the sen-
sor cover, this could shift
transducer calibration.
Caution!
When using toxic or cor-
rosive gases, purge the
unit thoroughly with inert
dry gas before discon-
necting from the gas line.