TM-9-2350-311-20-2

HOWITZER, MEDIUM, SELF-PROPELLED, 155MM; M109A2, M109A3, M109A4 AND M109A5

TECHNICAL MANUAL; UNIT MAINTENANCE MANUAL FOR CAB, ARMAMENT, SIGHTING AND FIRE CONTROL, ELEVATING AND TRAVERSING SYSTEMS AND ASSOCIATED COMPONENTS

DECEMBER 1993
TM-9-2350-311-20-2

  TM-9-2350-311-20-2 - Page 718 of 828

TM 9–2350–311–20–2
19–10
Change 2
19–2 RECUPERATOR ASSEMBLY — CONTINUED
c.
Servicing with High Pressure Nitrogen (Method Two) — Continued
CAUTION
Charging the system too fast will heat the dry nitrogen. This will give an inaccurate reading because
the pressure will decrease when the nitrogen cools, possibly causing equipment to malfunction.
NOTE
Estimated time to charge system is 30 minutes. System should be charged at ambient temperature
of weapon use.
13
Open safety-relief valve (23) until all nitrogen is bled from recuperator cylinder (3); then close safety-relief
valve.
14
Repeat steps 12 and 13 to remove all traces of moisture prior to charging system to full pressure with nitro-
gen.
15
Open pressure regulator valve (18) slowly, turning clockwise until pressure on 3000 psi gage (19) registers
100 psi (690 kPa) at 70
°
F (21
°
C).
16
Open stop-check valve (15) slowly, allowing nitrogen to charge recuperator assembly.
17
Open pressure regulator valve (18) to raise pressure at 100 psi (690 kPa) increments until gage (24) stabi-
lizes at 700 psi (5171 kPa) at 70
°
F (21
°
C).
WARNING
Failure to close nitrogen valve on recuperator cylinder could result in injury to personnel from high
pressure gas.
18
Close nitrogen valve (14) and shutoff valve (17). Let system set for one hour after charging.
WARNING
Failure to open safety-relief valve could result in injury.
19
Open safety-relief valve (23) to bleed pressure from nitrogen charging assembly (10) and air pressure gage
assembly (22).
20
Disconnect nitrogen charging assembly (10) and air pressure gage assembly (22) at angle valve (13).
21
Close pressure regulator valve (18) by turning counterclockwise.
22
Disconnect nitrogen charging assembly (10) from shutoff valve (17).
23
After one hour wait, close safety-relief valve (23).


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