TM-9-2350-311-10

TM 9-2350-311-10

2–17 OPERATING AUXILIARY EQUIPMENT — CONTINUED

2-17.6 NBC Equipment (M109A4/M109A5 Howitzers) — Continued

a. General

The NBC equipment illustrated below is provided in M109A4/M109A5 howitzers. It is used against toxic gases in an

NBC environment and during extremely dusty conditions to cleanse the air for the crew. Air is filtered through the M2A2

air purifiers, warmed in the M3 electrical air heater, and distributed through the hoses to the M25A1 masks. Hull NBC

equipment consists of an M2A2 air purifier, an M3 electrical air heater in the driver’s compartment, an M3 electrical air

heater below the bearing/race ring assembly near the gunner’s station, and connecting hoses. Cab NBC equipment

consists of four M3 electrical air heaters on the cab roof, an M2A2 air purifier on the right cab wall, and connecting

hoses. The cannoneers’ seats and NBC stowage boxes mounted to back hull provide stowage for NBC MOPP gear.

• Neither the M2A2 air purifiers nor the M25A1 masks will protect against carbon monoxide.

They will only get rid of odors which would normally indicate the presence of carbon

monoxide.

• When outside temperature is below 32° F (0° C), do not connect the M25A1 mask to orifice

connector immediately or frostbite could result. Use the M25A1 mask only. Run M3

electrical air heaters 15 minutes to heat filtered air before using in cold weather.

• Use care when washing vehicle interior to ensure water does not enter M2A2 air purifiers.

Water will damage the charcoal filters contained in the M2A2 air purifiers.

• If M10 canister on the M25A1 mask is being used for the first time or has been rough

handled, hook M25A1 mask up to a hose, turn on NBC system, and ventilate M25A1 mask

for an hour before using. Refer to TM 3-4240-280-10 for more detailed information about

the M25A1 mask.

b. Operation of Hull NBC Equipment

NOTE

Unused outlet holes on M2A2 air purifier should be covered with caps without center holes. Caps

with center holes are used during testing.

1 Turn MASTER switch (1) to ON.

2 Open spring clip (2) on hull M2A2 air purifier (3) to expose air inlet holes.

3 Turn NBC power switch (4) to ON and NBC indicator light (5) will illuminate.

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