TM 3-4240-212-14&P
CHAPTER 2
OPERATING INSTRUCTIONS
Section I. PREPARATION FOR USE
WARNING
2-1.
Before Operating
Never allow any substance to enter the canister
a. Remove M20 breathing apparatus from carrying
neck-especially oil, gasoline, or grease. The
case.
canister contains oxygen producing chemicals
b. Inspect apparatus for loose or missing parts and
which will cause flammable material to burn.
for any apparent damage. Give special attention to the
Keep the outside of the canister, the foil seal,
backplate assembly, harness assembly, canisters, and
and the Inside of the plunger valve assembly
hood.
free of moisture, oil, dirt, or grease.
c. Test pressure relief valve operation (para 3-2).
CAUTION
Do not pull lanyard on quick-starting canister
before installation or canister will deform and
f.
Ensure that inside of plunger valve assembly is
blow out the seal and gasket.
free of oil, dirt, or grease.
(1) If available, use a standard canister when
g. Clean lenses with a soft cloth and rub with
temperature is above 50 F.; use a quickstarting canister
antifogging cloth.
if temperature is from 30 to 50F.
F
h. Report
any
defects to organizational
(2) Pull tab extending from canister tear-off cap
maintenance personnel.
(use pliers, if needed, to remove cap).
(3) Remove disk from canister foil seal,
2-2.
Assembling Breathing Apparatus
(4) If a quick-starting canister is used, remove
a. Installing Hood on Facepiece.
cover from candle-starting mechanism by lifting end of
(1) Thread coupling end of breathing tube
cover nearest bottom edge of canister. Slide cover
assemblies through hood opening (A, fig. 2-1) so that
toward center of canister base.
breathing tubes and valve assembly extend outside the
(5) Allow cover to dangle from lanyard; DO NOT
hood.
PULL LANYARD AND RELEASE COTTER PIN AT THIS
(2) Fit hood opening around top of lenses and
TIME.
around bottom of facepiece (B) below valve assembly.
d. Installing Canister.
b. Connecting Breathing Tubes.
(1) Turn
handwheel
on
bail
assembly
(1) Connect exhalation breathing tube coupling to
counterclockwise until pressure plate clears canister
threaded inlet at top of plunger valve assembly. Turn
guard.
coupling fingertight (as tight as possible with the fingers).
(2) Insert canister in guard and swing bail back
(2) Connect inhalation breathing tube coupling to
until bottom of canister rests on pressure plate.
threaded outlet of inhalation elbow.
Turn coupling
(3) Turn handwheel clockwise until canister neck
fingertight.
is firmly seated in plunger valve assembly.
(3) Tighten both couplings with spanner wrench.
(4) When a quick-starting canister is installed,
(4) Unsnap the breathing tube straps (1, fig. B-
pass loosened candle cover and lanyard through bail
3). Place one breathing tube inside each strap and
assembly toward front of apparatus so that the cotter pin
refasten. The straps hold the breathing tubes in position
can be removed by a direct pull, DO NOT PULL COTTER
when wearing the apparatus.
PIN AT THIS TIME.
c. Preparing Canister.
Section II. OPERATION UNDER NORMAL CONDITIONS
put on before starting; otherwise, it must be started and
2-3.
Starting Apparatus
then put on.
b. Starting Apparatus Using Standard Canister.
(1) Place apparatus on a flat surface so that
Change 2
2-1
