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TM 3-1040-220-12&P
Section VI. PRESSURE GROUP
(c) Remove two nuts and two mounting clips from
4-13. Dial Indicating High Pressure Gage
the back of the gage.
(d)
Remove the gage.
a. Description and ,'Function. This gage is scaled
(2) Installation.
from zero to 3.000 pounds per square inch (psi)
(a) Coat the threads of the gage with sealing
graduated in labeled increments of 500 psi. This gage is
compound (NSN 8030-00-209-8005) or Teflon antiseize
a round dial bourdon tube type. The dial indicating
tape (NSN 8030-00-889-3535).
pressure gage indicates air-pressure in the compressed
(b) Installation of the gage procedure is the reverse
gas cylinders when the globe valve is open.
of removal procedure, (1) above.
WARNING
4-15. Rupture Disk
Make sure that all pressure has been relieved from the
cylinders before performing any maintenance operation
a. Description and Function. The rupture disk is a
on any component of the disperser. b. Maintenance.
soft aluminum disk. It is designed to rupture when air
Organizational maintenance personnel Preauthorized to
pressure against it exceeds 110 pounds per square inch
replace the high pressure dial indicating pressure gage.
(psi). This rupture disk is located inside the safety head
assembly. The rupture disk is the pressure relieving
(1) Removal.
device used to prevent a build up of excessive air
(a) Open the angle valve, globe valve, and the lever
pressure if the pressure regulator and relief valve
plug valve. Relieve pressure in the agent container by
malfunction. The safety head assembly consists of a
manually operating the lever of the pressure relief valve.
safety head screw, a retaining ring, a rupture disk, and
(b) Disconnect the threaded connector of the
the safety head body. The safety head assembly is
nonmetallic hose assembly from the reducer at the back
mounted in the cross that is above the lever plug valve
of the gage.
and protrudes through the front of the control panel.
(c) Remove two nuts and two mounting clips from
When the rupture disk ruptures, air pressure escapes to
the back of the gage.
the atmosphere.
b. Maintenance. Organizational
(d) Remove the gage.
maintenance personnel are authorized to replace the
(2) Installation.
rupture disk.
(a) Coat the threads of the gage with sealing
(1) Removal.
compound (NSN 8030-00-209-8005) or teflon antiseize
(a) Open the angle valve, globe valve, and the lever
tape (NSN 8030-00-889-3535).
plug valve. Relieve pressure in the agent container by
(b) Installation procedure is the reverse of removal
manually operating the lever of the pressure relief valve.
procedure, (1) above.
(b) Loosen the fitting (locknut) that locks safety head
4-14. Dial Indicating Low Pressure Gage
threads in the cross. Unscrew the safety head and fitting
from the cross as a unit.
a. Description and Function. This gage is scaled
from zero to 200 pounds per square inch (psi), graduated
(c) Use one open end wrench to hold safety head
at 10 pound psi increments with labeled graduations
body. Use a second wrench to remove the safety head
every 20 units. This gage indicates air pressure in the
screw.
agent container when the lever plug valve and the globe
(d) Remove the retaining ring and the expended
valve (para 4-13) are open.
b. Maintenance.
rupture disk. Discard the rupture disk.
Organizational
maintenance personnel are authorized
to replace the low pressure dial indicating pressure gage.
(2) Installation.
(1) Removal.
(a) Install a new rupture disk in safety head body.
(a) Open the angle valve, globe valve, and `.h lever plug
Install a new retaining ring in the safety head body.
valve. Relieve pressure in the agent container by
(b) Apply a coat of sealing compound (NSN 8030-
manually operating the lever of the pressure relief valve.
00-209-8005) or Teflon antiseize tape (NSN 8030-00-
(b) Disconnect the threaded connector of the
889-3535) to threads of safety head screws.
nonmetallic hose assembly from the elbow at the gage.
(c) Screw the safety head screw into the safety
head body. Be careful to keep the rupture disk over the
opening (properly positioned). Tighten the safety head
screw handtight.
4-7
