Type EZH Relief or Backpressure Regulator
5
6. The Type PRX/182 pilot spring case vent (key 12,
Figure 7) must be kept open to atmospheric pressure.
Protect the vent assembly from icing, moisture, or debris
that may cause blockage, as required. To change the
vent orientation, twist the vent assembly in the spring
case. To remotely vent the pilot spring case, remove the
vent assembly and install tubing or piping into the 1/4 NPT
spring case vent tapping. Protect the open end of the vent
line by installing a screened vent cap.
7. The Type PRX pilot connections are 1/4 NPT. Connect
the inlet control (sense) line from the “A” port, Figure 6
(key 47) on the bottom of the PRX
Series pilot to a straight
run of pipe 6 to 10 pipe diameters from the relief valve or
backpressure regulator inlet as shown in Figure
3 using
3/8-inch / 9.5 mm or larger outside diameter tubing. If such
a distance is not practical, connect the control line away
from elbows, swages, nipples, or any area where abnormal
flow velocities occur.
Startup and Shutdown
CAUTION
If pressure is introduced first to the main
valve before the pilot, the main valve may
go wide-open and subject the downstream
system to full inlet pressure.
Note
The maximum inlet pressure for specific
constructions are given in Table 6. Use a
pressure gauge to monitor inlet pressure
during startup.
Relief Installation (Figure 6)
Startup
1. Close vent valve (not shown).
2. Slowly open block valve and hand valve, if installed.
3. Adjust the pilot as needed.
Shutdown
1. Close block valve and hand valve, if installed.
2. Slowly open vent valve (not shown).
Backpressure Installation
Startup
1. Close upstream and downstream vent valves
(not shown).
2. Slowly open upstream block valve first and then slowly
open downstream block valve.
3. Adjust the pilot as needed. If the pilot is not piped
downstream, make sure the pilot exhaust is pointed in
the correct direction.
Shutdown
1. Close upstream block valve first and then close the
downstream block valve.
2. Open downstream and upstream vent valves
(not shown).
Type PRX/182 Pilot Adjustment
For PRX Series pilots (Figure 7), loosen locknut
(key 2) and turn the adjusting screw into the spring case
to increase (or out of the spring case to decrease) the
downstream pressure. When the required downstream
pressure is maintained for several minutes, tighten the
locknut to lock the adjusting screw in position.
!
WARNING
Avoid personal injury or damage to property
from sudden release of pressure or
uncontrolled gas or other process fluid. Before
starting to disassemble, carefully release
all pressures according to the appropriate
shutdown procedure. Use a gauge to monitor
relief (inlet) pressure while releasing it.
CAUTION
Use proper lifting techniques, when lifting the
upper and lower actuator casings (keys 11
and 5) off the Type EZH body (key 1). The
actuator assembly weighs more than
100 pounds / 45 kg.
Customer cannot use another type of eyebolt
in the regulator. Only Regulator Technologies
parts can be used to repair the unit.
Eye bolts are installed to aid in the handling
and installation of the Regulator Assembly
only. Do not attempt to lift more weight than
the regulator with these eye bolts.
Maintenance
Relief valve or backpressure regulator parts are subject
to normal wear and must be inspected periodically and
replaced as necessary. Due to the care Fisher
®
takes in
meeting all manufacturing requirements (heat treating,
dimensional tolerances, etc.), use only replacement parts
manufactured or furnished by Fisher. Also when lubrication
is required, use a good quality lubricant and sparingly coat
the recommended parts.
The frequency of inspection and replacement depends upon
the severity of service conditions and upon applicable codes,
government regulations, and company standards.
