Automatic Combustible Gas Alarm

TM 5-6640-213-14

(7)

Troubleshooting.

A troubleshooting chart for the air

system is listed in table 3-4.

AUTOMATIC

COMBUSTIBLE

GAS

ALARM.

3-5.

Inspections.

(1)

Daily

(a) Inspect the instrument and pilot lights to see

that they show normal operation.

(b) Check the meter

readings

and

investigate

any

abnormal

deviations from zero.

(2) Weekly.

Check meter readings and adjust zeros if

necessary

while detectors are in a combustible gas-free environment.

(3) Periodic.

Check response of the instrument period-

ically by exposing the detector to a sample of combustible gas of

known concentration.

Services.

(1) Replace

pilot, alarm and fail lights when found defec-

tive in operation.

(2)

Calibrate

the

instrument,

follows:

(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-

cially.

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.

Detector

Voltage

Measurement

and

Element

Replacement.

(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

detector (A, fig. 3-5 and item 7, fig. 2-8).

Refer to figure 3-5 and

proceed as follows: