Vent or
Reservoir
Bypass
Supply
@ P
1
SRV
PI
Model 8311HP or 8311LP
Back Pressure/Relief
Regulator
System
Recommended Piping Schematic
for Models 8311HP/LP
INSTALLATION, OPERATION & MAINTENANCE MANUAL
IOM-8311HP/LP-BASIC
12-13
1. An inlet block valve should always be installed.
2. If service application is continuous such that shut down
is not readily accomplished, it is rec om mend ed that
an inlet block valve, outlet block valve, and a manual
bypass valve be installed.
3. Pipe unions are recommended for NPT screwed in stal -
la tions to allow removal from piping.
4. An inlet pressure gauge should be located ap prox i mate ly
ten pipe diameters upstream, and within sight.
5. All installations should include a upstream re lief device
if the inlet pressure could exceed the pressure rating of
any upstream equipment or the maximum inlet pres sure
rating of the unit.
6. Clean the piping of all foreign material including chips,
welding scale, oil, grease and dirt before in stall ing the
regulator. Strainers are recommended.
l. DESCRIPTION AND SCOPE
The Model 8311 is a high capacity back pressure / relief regulator with double seat design used to control upstream (inlet or P
1
)
pressure. Sizes are 1-1/2" (DN40), 2" (DN50), 2-1/2" (DN65), 3" (DN80) and 4" (DN100). With proper trim utilization, the unit
is suitable for liquid, gas eous, or steam service. Refer to Tech ni cal Bulletin 8311-TB for design conditions and selection recom-
mendations.
This is not a safety device and must not be sub sti tut ed for a code
approved pressure safety relief valve or rupture disc.
SECTION II
II. INSTALLATION
7. In placing thread sealant on pipe ends prior to en-
gage ment, ensure that excess material is re moved and
not allowed to enter the regulator upon start-up.
8. Flow Direction: Install so the
fl
ow direction match es the
arrow on the body. Install an external sensing line (1/2"
O.D. tubing min i mum) from the 3/8" NPT con nec tion
to a point up stream, pref er a bly at gauge location. If
regulator pipe line is ex pand ing to a larger pipe line,
always connect sensing line to the larger pipe line.
9. For best performance, install in well drained hor i zon tal
pipe, properly trapped, if a steam service ap pli ca tion.
MODELS 8311HP AND 8311LP
BACK PRESSURE / RELIEF REG U LA TORS
SECTION l
CAUTION
Installation of adequate overpressure pro tec tion is recom-
mended to pro tect the reg u la tor from overpressure and
all down stream equip ment from damage in the event of
regulator failure.
WARNING
The maximum inlet pressure is equal to 1.3 times the
larger number of the stated range spring on the nameplate,
and is the recommended “upper op er a tive limit” for the
sensing diaphragm. Higher pres sures could damage the
diaphragm. (Field hy dro stat ic tests frequently destroy
diaphragms. DO NOT HYDROSTATIC TEST THRU AN
IN STALLED UNIT; ISOLATE FROM TEST.)
CAUTION
