Overview
150-454-111-06
6
February 25, 2000
HRE-454
P
RESSURIZED
A
PPLICATIONS
For pressurized applications on the HRE-454, the Schrader air stem valve is used. A pressure gauge is attached to
the valve for the purpose of measuring the internal pressure of the enclosure. This valve is also used to relieve the
internal pressure prior to opening and removing the dome cover. This can be done by depressing the center pin on
the valve (see
and
for air stem valve and pin locations).
Figure 3.
HRE-454 Air-filled Remote Enclosure
A breather vent valve is enclosed in an air-filled shipping kit. The kit is a small plastic bag attached to a red and
brown colored spare pairs shrink tube. The breather vent valve replaces the pressure relief valve if the air-filled
unit is not pressurized. The assembly allows the enclosure to breathe and keeps the internal atmosphere free of
harmful contaminants. The five metal valves are shown in
.
To avoid pressure buildup, the pressure relief valve is set to release air at a maximum pressure
of 15 PSI. Due to manufacturing tolerances of the springs, this maximum pressure has a
tolerance of +/- 3 PSI. This pressure and tolerance is well within the safety concerns that may
apply to the housing, personnel, or cable.
The pressure relief valve is not intended for controlling the air pressure that is being applied to
the housing cable.
Depressurizing must be performed every time the cover is removed from the List 2A, List 2B,
List 4, and List 6 equipment. Failure to do so may cause personal injury or damage to the
equipment. This also applies to a gel-filled unit that is being locally pressurized.
