RKI Instruments GP-01 with self resetting alarms - Manual (Page 10)

10 • Description Model GP-01 Operator’s Manual
they turn dark brown. Frequency of replacement depends on how often the
Model GP-01 is exposed to H
2
S and on the concentration of H
2
S in the
environment. If installed, check the condition of the H
2
S scrubber filter
disks every three months.
NOTE: See “Combustible Gas Detection” on page 15 for a discussion of
when the H
2
S scrubber disks should be used and how they affect
detection of certain gasses.
The sensor cover fits into a larger recessed area and covers the two H
2
S
scrubber filter disks (if installed). It is held in place by the membrane
retainer and one Phillips screw. The sensor cover should be inspected
periodically and replaced if contaminated by dirt or moisture. Refer to
“Maintenance” on page 25 for H2S scrubber and sensor cover replacement
instructions.
Sensor Retainer
The sensor retainer holds the combustible gas sensor in place. It is
attached to the top of the case by two Phillips screws. The sensor retainer
also covers the buzzer.
Should the combustible gas sensor require replacing, refer to the
Maintenance section for sensor replacement instructions. The buzzer,
however, is not field replaceable.
The sensor retainer has a single diffusion port through which ambient air
reaches the combustible gas sensor. A recessed area in the sensor
retainer accepts two H
2
S scrubber filter disks and the sensor cover, which
covers the H
2
S scrubber filter disks if they are installed. The membrane
retainer is installed to the top of the sensor retainer with a single Phillips
screw.
Combustible Gas Sensor
The combustible gas sensor detects combustible gas and vapors in the
atmosphere with a catalytic element. The reaction of gas with oxygen on
the catalyst causes a change in the resistance of the element, which
affects the current flowing through it. The current is amplified by the Model
GP-01’s circuitry, converted to a measurement of combustible gas
concentration, and displayed on the LCD.
CAUTION: Do not expose the combustible gas sensor to high
concentrations of combustible gas, which are found, for
example, in a butane lighter. Exposure to high concentrations
of combustible gas may adversely affect the performance and
life of the combustible gas sensor.