TM 5-4310-344-34
b. Inspect parts for damaged screw threads,
d. Use same test set-up as illustrated in figure
cracks, breaks or worn areas in anodized surfaces, and
other obvious indications of wear, damage and
and connect an adjustable source of high pressure
compressed air to high pressure inlet port of pneumatic
dump valve.
c. Inspect finished surfaces of body, stem,
adjusting screw and metal ball for scoring, scratches,
e. With an air pressure of 60-to 65-psig
nicks and signs of wear.
applied to low pressure inlet port, apply a gradually
increasing air pressure to high pressure inlet port.
d. Do not attempt to repair damaged or
Increase pressure to 3100 100 psig, then shut off high
questionable parts. Discard all such items and install
pressure air supply.
new parts during reassembly.
f.
Piston in pneumatic dump valve should
2-23.
REASSEMBLY.
remain closed to maintain high inlet air pressure. When
it is evident that piston is closed, connect a flowmeter to
dump valve exhaust port. Measured leakage shall not
a. Apply a thin film of pneumatic system
exceed five cubic inches per minute.
grease MIL-G-4343 to new preformed packing (10),
packing groove in body (11), and mating surfaces of
g. After completing tests, relieve air pressure
body and piston assembly (7).
in test set-up, disconnect pneumatic dump valve.
b. Insert preformed packing (10) in groove in
2-20. PRESSURE RELIEF VALVE. The pressure
bore of body (11). Install ball return spring (9) and metal
ball (8) in bore of body.
relief valve is Installed at the outlet port to protect the air
system from excessive back pressure. The valve
c. Install piston assembly (7) in body (11) and
exhausts air to atmosphere at a pressure of 3950 psig
down over metal ball (8) and spring (9).
(max) and reseals when pressure is no less than 3350
psig.
d. Insert spring retainer (6), cupped side
2-21.
against piston assembly (7).
e. Place shim (5) and spring (4) in body (11).
a. Cut safety wire and remove wire and lead
Screw adjusting screw (2) into body. Screw stem (3)
seal. Unscrew adjusting screw (2) and stem (3) from
into adjusting screw.
body (11).
2-24.
TEST AND ADJUSTMENT.
b. Remove spring (4), shim (5), spring
retainer (6) and piston assembly (7) from body (11).
a. Install pressure relief valve in test set-up as
Note
illustrated schematically in figure 2-3. Be sure to
observe dimensions specified for approach and exit
sections.
Do not disassemble piston assembly
(7). The parts are installed and crimped
b. Close bleed valve.
Adjust pressure
within the retainer and cannot be
regulator to apply a gradually increasing air pressure to
removed
without
destroying
the
approach section. Relief valve should open (i.e., air
assembly.
flow from leakage tube exceed three cubic centimeters
per hour) before applied pressure reaches 3500-to 3800-
c. Remove metal ball (8), ball return spring
psig.
(9) and preformed packing (10) from body (11).
2-22.
CLEANING AND INSPECTION.
c. If relief valve falls to open, remove
collector cup, adjust stem of valve a small amount,
replace collector cup, and repeat test. Repeat alternate
a. Wash all parts with dry cleaning solvent,
adjustments and tests until relief valve opens, as
Federal Specification P-D-680, and dry thoroughly with
indicated by a minimum air flow of 0.6 scfm, with an
clean, lint-free cloths. Use filtered, compressed air to
approach section pressure of 3500-to 3800psig
blow solvent and residue from all crevices, springs, and
maximum.
air passages.
2-6
