150-506-100-03
Appendix B: Additional Information
HRE-506 List 1 and List 2
March 28, 2000
41
V
ALVE
R
EPLACEMENT
P
ROCEDURES
All but the Air Stem Inlet T-valve, shown in
, can be replaced if needed. Order the valve
replacement kit #132-1038-01 listed in
to obtain new valves. Use the following procedures
when replacing any of the four valves.
Replacing the Pressure Relief Valve
The Pressure Relief Valve (PRV) is part of an all metal, nickel plated brass assembly, shown in
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 base plate 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 the PRV 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
Grip the adapter nut with a
3
/
4
-inch wrench and the PRV with a
1
/
2
-inch wrench and tighten the the PRV to
120 inch-pounds of torque.
6
Pressurize the chamber and check the entire assembly for leaks.
Replacing the Breather Vent Valve
The Breather Vent Valve (BVV) is an all metal, nickel plated brass unit, as shown in
. It allows
air to circulate into the enclosure so it can breath and avoid the build up of excessive moisture and other
contaminates. It has a hollow-threaded stem that connects into a brass fitting located at 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 the valve by
hand.
2
Check that the new BVV is equipped with its O-ring.
3
Thread the BVV into the brass fitting. Do not crossthread.
4
Grip the BVV with a
3
/
4
-inch wrench and tighten the valve to 60 inch-pounds of torque.
Do not overtighten. Excessive torque does not improve the seal and may damage the PRV.