ADC 150-1122-03, User Manual

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Appendix B - Technical Reference 150-454-111-06
60 February 25, 2000 HRE-454
V
ALVE
R
EPLACEMENT
P
ROCEDURES
All but the Air Stem/Air Intake T-valve shown in Figure 4 on page 7 can be replaced, if needed. Order the valve
replacement kit #132-1038-01 listed in Table 13 on page 59 to obtain new valves. Use the following procedures
when replacing any of the four replaceable valves.
Pressure Relief Valve
The pressure relief valve (PRV) is part of an all metal, nickel-plated brass assembly as shown in Figure 4 on
page 7 . The valve acts as a guard against over-pressurizing the enclosure and releases the internal pressure when
it exceeds a nominal level of 15 PSI. The assembly consists of an adapter that screws into a brass fitting located
in the bottom of the baseplate and the PRV valve itself which screws into this adapter. The adapter has two O-rings
that are required to create an airtight seal. One is located on its outer threaded stem that connects to the brass
fitting; the other is located at the base of its inner well where it seals the PRV to the adapter.
To remove and replace the PRV, proceed as follows:
1 Grip the adapter nut with a
3
/
4
-inch wrench and the PRV with a
1
/
2
-inch wrench.
2 While holding the adapter nut steady (it should not be moved), loosen the PRV by turning it
counterclockwise, then remove it by hand. If the adapter nut becomes loose, tighten it to a torque of 60
inch-pounds.
3 Check that the O-ring in the adapter’s inner well has remained in place. If not, reseat it.
4 Thread the new PRV into the adapter. Do not crossthread.
5 Again grip the adapter nut with a
3
/
4
-inch wrench and the PRV with a
1
/
2
-inch wrench. Tighten the PRV to
120 inch-pounds of torque.
6 Pressurize the chamber and check the entire assembly for leaks.
Breather Vent Valve
The breather vent valve (BVV) is an all metal, nickel-plated brass unit as shown in Figure 4 on page 7 . It allows
air to circulate into the enclosure so it can breathe and avoid the buildup of excessive moisture and other
contaminants. It has a hollow-threaded stem that screws into a brass fitting located on the bottom of the base. An
O-ring is located on its outer threaded stem that connects to the brass fitting. The hollow stem contains a piece of
plastic screen to prevent insects from migrating into the enclosure.
To remove and replace the breather vent, proceed as follows:
1 Grip the BVV with a
3
/
4
-inch wrench and loosen by turning it counterclockwise, then remove it by hand.
2 Check that the new BVV came equipped with its O-ring.
3 Thread the new BVV into the brass fitting. Do not crossthread.
4 Again grip the BVV with a
3
/
4
-inch wrench and tighten to 60 inch-pounds of torque.
Do not overtighten. Excessive torque does not improve the seal and may damage the PRV.