HSRL Series
6
Large volumes of gas may discharge
through the regulator vent during
internal relief valve operation, which
can, if not controlled, result in fire or
explosion from accumulated gas.
The HSRL Series regulators contain internal relief
valves. The internal relief valve in all units will give
overpressure protection against excessive build-
up resulting from seat leakage due to worn parts or
chips or foreign material on the orifice. The amount
of internal relief protection provided varies with the
regulator type and the cause for the overpressure
relief valve operation. When the internal relief valve
opens, gas escapes to the atmosphere through the
regulator’s vent.
Some type of additional external overpressure
protection must be provided if the outlet pressure in
an overpressure condition exceeds the inlet pressure
rating of the gas system or downstream equipment.
Common methods of external overpressure protection
include relief valves, monitoring regulators, shutoff
devices, and series regulation.
Maintenance
!
WaRninG
To avoid personal injury or equipment
damage, do not attempt any maintenance
or disassembly without first isolating
the regulator from system pressure and
relieving all internal pressure.
Regulators that have been disassembled
for repair must be tested for proper
operation before being returned to
service. Only parts manufactured by
Fisher
®
should be used for repairing
Fisher regulators. Relight pilot lights
according to normal startup procedures.
Due to normal wear or damage that
may occur from external sources,
these regulators must be inspected and
maintained periodically. The frequency
of inspection and replacement of the
from the regulator’s internal relief valve. Vent lines
should be at least 3/4-inch NPT pipe or 3/4-inch
NPT size, Gray PVC Schedule 40 Rigid Non-metallic
Electrical Conduit for above Ground Service, per
Underwriters Laboratories (UL
®
) 651. To install the
vent line, remove the vent screen and apply a good
grade of pipe dope to the male threads of the line.
Vent lines should be as straight as possible with a
minimum number of bends.
adjustment
To increase the outlet pressure setting of the
regulator, the adjusting screw must be turned
clockwise. This requires removal of the closing
cap. To reduce the outlet pressure setting, turn
the adjusting screw counterclockwise. A pressure
gauge should always be used to monitor downstream
pressure while adjustments are being made. Do not
adjust the spring to produce an outlet pressure setting
above the limit identified on the information label.
After the spring adjustment has been completed,
replace the closing cap.
Overpressure Protection
!
WaRninG
Some type of overpressure protection
is needed if actual inlet pressure can
exceed the outlet pressure rating.
Overpressuring any portion of this
equipment above the limits shown in
the Specifications section may cause
damage to regulator parts, leaks in
the regulator, or personal injury due to
bursting of pressure-containing parts or
explosion of accumulated gas.
if any portion of the regulator is exposed
to an overpressure condition that
exceeds the limits in the Specifications
section, it must be inspected for damage
that may have occurred.
