Amber Warn Light

TM 5-6640-213-14

when a combustible gas condition exceeding the low alarm settng

exists at the remote detector, or when the alarm test switch ((e)

below) has been actuated.

(d) Red Alarm Light. The red alarm light comes on

when a combustible gas condition exceeding the high alarm setting

exists at the remote detector, or when the alarm test switch has been

actuated.

(e) Alarm Test Switch. The alarm test switch is a

momentary contact pushbutton switch incorporated with the warn light.

When it is depressed electrically, there is a simulation of an alarm

level of gas concentration at the remote detector. This switch

provides a functional check of the analyzer and remote alarm circuit.

(f) Alarm Reset Switch. The alarm reset switch is a

momentary contact pushbutton switch located on the cabinet door.

Depressing the switch deactivates the holding circuits of the alarm

and warning relays if a safe gas condition has been restored at the

remote detector. If a safe condition does not exist, the unit cannot

be reset.

(g) Indicator Meter. The indicator meter shows the

concentration of combustible gas at the detection point.

(h) Terminals. Terminals are accessible when the

front panel is open and the printed circuit card is removed. Term-

inals are provided for incoming power, remote detector leads, alarm

and failure devices, and for external warning devices and recorder,

if desired.

(3) Alarm System Detector. The detector consists of the

body, detector element and shield assembly. The body houses the

detector element and holds the shield in place. The element is a

replaceable gas sensing unit that plugs directly into the body when

the shield is removed. The shield assembly consists of a shield and

a flashback screen, which prevents ignition of combustible gases.

The detector, which is explosion proof, is located in an area where

flammable gas or vapor may be released. It is mounted on a 3/4 inch

conduit that leads to the cabinet assembly; the detector lead enters

the cabinet through 3/4 inch conduit fittings.

(4) Placing the Alarm System in Operation.

(a) Initial Startup Procedures.

1. Turn on the power (the pilot light should

come on). A 45-second delay disables the alarm circuits to permit

instrument warmup. Allow the system to stabilize for 5 minutes.

2. Make sure that the remote detector is in a

combustible gas-free area. The area surrounding the detector can be

checked by using a portable combustible gas indicator.

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