RKI Instruments GX-94 - Manual (Page 45)

GX-94 Operator’s Manual Page 44
2. Remove the diffusion screen.
3. Remove the old charcoal filter w/rubber boot from the CO sensor
diffusion port. Place the new filter in the filter slot. Replace the filter
when CO readings become suspect (e.g., CO circuit calibrates
properly, but shows response in a known CO-free environment), or
when replacing sensor, whichever comes first.
4. Replace the diffusion screen.
5. Replace the diffusion screen retaining screw.
Sensor Maintenance
Electrochemical sensors (O
2
, H
2
S, CO) gradually deteriorate, regard-
less of use, and require periodic replacement. Combustibles sensor life
is generally related to exposure to combustible gas, but certain environ-
mental factors may affect duration.
The GX-94 sensors are easy to replace but contain no user serviceable
parts. For genuine RKI sensors, call RKI or your local distributor. All
sensors are covered by a limited warranty; see warranty for details.
Combustibles Sensor
Replace the combustibles sensor when:
1. The combustibles circuit cannot be calibrated correctly.
2. The HC (%LEL) display does not show 0 immediately after the
start-up sequence, and it cannot be set to zero by the Demand
Zero command.
O
2
Sensor
Replace the O
2
sensor when:
1. The O
2
circuit cannot be set to 00.0% on an oxygen-free sample.
2. The OXY (O
2
) display does not show 20.9% immediately after the
start-up sequence and after the Demand Zero operation.
3. The O
2
reading tends to drift with instrument orientation.