Section VIII. MAINTENANCE OF PRESSURE CONTROL
4-19. Pressure Control (Fuel Drums Only).
a. Cleaning and Inspection (Exterior), Testing
(1) Using a mild soap and water solution with a
stiff bristle brush, remove foreign matter from the
(2) Inspect pressure control for cracked, loose,
or missing parts.
(3) Test and adjust pilot valve (para 4-22).
b. Repair. When it becomes necessary to repair
and adjust the pressure control, the procedures in
paragraphs 4-20 thru 4-25 will be followed as re-
4-20. Diaphragm Valve.
a. Removal and Disassembly.
(1) Remove the plug (1, fig. 4-10) from the cover
(3) as necessary.
(2) Hold down the cover (3) firmly to prevent
spring action and remove the nuts (2) from studs
(14). Gradually release the pressure on the cover
and remove the cover from the studs.
(3) Unscrew and remove guide shaft (4) from
(4) Remove spring (5) from the pressure con-
trol. Lift the diaphragm valve from the pressure
(5) Remove the nut (6) from machine screw (13).
(6) Remove the large washer (7), diaphragm (8),
poppet (9), disk (10), spacer (11) and small washer
(12) from the machine screw (13).
b. Cleaning, Inspection and Repair.
(1) Wash all metal parts in a hot, mild soap and
water solution and dry the parts with a clean cloth.
(2) Inspect the machine screw and guide shaft
to determine if they are bent, cracked, broken, bur-
red or have stripped threads.
(3) Inspect the nut for stripped threads and a
(4) Inspect the diaphragm and disk to deter-
mine if they are cut or deteriorated.
(5) Inspect the spring to determine if it is
broken or collapsed.
(6) Inspect the poppet, spacer and washers to
determine if they are cracked or burred.
(7) Replace all unserviceable parts.
c. Reassembly and Installation.
(1) Place the small washer (12, fig. 4-10),
spacer (11), disk (10) and poppet (9) on the
machine screw (13).
(2) Place the diaphragm (8) on the machine
(3) Place the large washer (7) on the machine
screw with the raised side against the diaphragm.
Install the nut (6) on the machine screw and tighten
(4) Align the holes in the diaphragm valve in
the pressure control.
(5) Screw the guide shaft (4) into the cover (3).
(6) Place the spring (5) over the diaphragm
(7) Align the holes in the cover with the studs,
and place the cover on the pressure control.
Assure the guide shaft is in the hole in
the machine screw.
(8) Install nuts (2) on the studs and tighten the
nuts to 20 foot-pounds (2.77 m-kg) torque.
(9) Insert plug (1) in cover.
4-21. Cycling Valve Assembly.
a. Removal and Disassembly.
(1) Hold the ring (2, fig. 4-1 1) in place and
remove the capscrews (1).
(2) Remove the ring (2) and cover (3) from the
(3) Grasp the button (4) and twist and pull it
until the cycling valve is removed from the
(4) Remove the preformed packings (11) from
the valve body (12).
(5) Apply pressure on the spring (8) with the
washer (9) and remove the retaining ring (10) from
the valve body.
(6) Remove the retaining ring (13) from the
cycling valve stem (6) and remove the valve body
from the cycling valve stem.
(7) Remove the washer and spring from the
cycling valve stem.