A troubleshooting chart for the air
system is listed in table 3-4.
(a) Inspect the instrument and pilot lights to see
that they show normal operation.
(b) Check the meter
deviations from zero.
Check meter readings and adjust zeros if
while detectors are in a combustible gas-free environment.
Check response of the instrument period-
ically by exposing the detector to a sample of combustible gas of
pilot, alarm and fail lights when found defec-
tive in operation.
(a) Expose the detector to a known concentration of
combustible gas in the air.
(b) Correct meter reading by adjusting the gain ad-
juster on the printed circuit board using a known concentration of
gas or the test and calibration kit, which can be obtained commer-
(c) Replace the detector element (c.(2) below) when-
ever it is no longer possible to make the zero adjustments within
the span of the zero adjuster on the corresponding control module.
Check detector voltage between the detector voltage test points on
the printed circuit board each time the element is replaced.
(1) Voltage measurement.
Two people are required to per-
form the initial detector voltage settings and measurement - one
person at the control unit (fig. 3-4) and one preson at the remote
Refer to figure 3-5 and
proceed as follows: