RKI Instruments GX-3R Pro - Filters

17 • Chapter 2: Description GX-3R Pro Operator’s Manual
Filters
Combustible Gas Sensor H
2
S Removal Filter Disk (Dark Red)
An H
2
S removal filter disk is placed into a recess in the filter gasket over the combustible gas
sensor. The filter disk prolongs the life of the combustible gas sensor by preventing H
2
S in the
ambient air from reaching the sensor. The H
2
S filter disk is dark red in color and although it may
darken over time, its color is not indicative of remaining filter life.
The H
2
S filter disk needs replacing once it’s been exposed to 33 ppm hours of H
2
S. This means
the filter needs replacing after 80 minutes of exposure to 25 ppm H
2
S which equates to 40 2-
minute calibrations with a cylinder containing 25 ppm H
2
S. If H
2
S exists in the monitoring
environment, the H
2
S filter disk will have to be replaced more frequently.
CO/H
2
S Sensor Dual Filter (Black and White)
A dual filter is placed into a recess in the filter gasket over the dual CO/H
2
S sensor. The black half
is a charcoal filter for the CO sensor. The white half is a humidity filter for the H
2
S sensor.
Replace the filter if you notice:
• Unexplained CO readings.
• For users with a 1 ppm H
2
S alarm setpoint: A drift on the H
2
S zero reading, unexplained
H
2
S readings, the filter appears dirty, or every 6 months (whichever is sooner).
CO Sensor Charcoal Filter (Black)
A black charcoal filter is placed into a recess in the filter gasket over the CO sensor. The charcoal
filter disk scrubs H
2
S and certain hydrocarbons out of the sample to avoid false CO readings. If
false or elevated CO readings are noticed, especially in the presence of H
2
S, change the charcoal
filter.
H
2
S and PH
3
Sensors’ Humidity Filter (White)
A white humidity filter is placed into a recess in the filter gasket over the H
2
S or PH
3
sensor (if an
H
2
S or PH
3
sensor is installed). The filter absorbs humidity in the sampling environment to
prevent unstable readings around 0 ppm. “H2S” and “PH3” are printed on the side of the filter.
•H
2
S: For users with a 1 ppm H
2
S alarm setpoint, the filter should be replaced every 6
months, if you notice a drift on the zero reading, or if the filter appears dirty (whichever is
sooner). For users with a 2 ppm or higher H
2
S alarm setpoint, the filter does not
necessarily ever need to be replaced.
•PH
3
: The filter should be replaced every 6 months.
NO
2
and SO
2
Sensors’ H
2
S Removal Filter Disk (Tan)
An H
2
S removal filter disk is placed into a recess in the filter gasket over the NO
2
or SO
2
sensor
(if an NO
2
or SO
2
sensor is installed). The filter disk prolongs the life of the sensors by preventing
H
2
S in the ambient air from reaching the sensor. The filter should be replaced every 6 months.
HCN Sensor’s H
2
S Removal Filter Disk (Dark Gray)
An H
2
S removal filter disk is placed into a recess in the filter gasket over the HCN sensor (if an
HCN sensor is installed). The filter disk prolongs the life of the sensors by preventing H
2
S in the
ambient air from reaching the sensor. The filter should be replaced every 6 months.