Bulletin 7337A-3
Page 3
INSTALLATION
If gas escaping through the internal relief could constitute a
hazard the spring case vent must be piped to a location where
escaping gas will not be hazardous. If the vented gas will be
piped to another location use obstruction-free tubing or piping at
least equal in size to the vent. The end of the vent pipe must be
protected from anything that might clog it.
OVERPRESSURE PROTECTION
Like most pressure-reducing regulators, the 7337A-3 Regulators
have outlet pressure ratings that are lower than the inlet pressure
ratings. Therefore, a pressure relieving or pressure limiting device
is needed if the inlet pressure can exceed the outlet pressure
rating, see "Specifi cations".
The regulators ending in "-SS" provide overpressure protection by
shutting off the fl ow of gas to the downstream system. This slam-
shut device functions by internal registration.
The internal relief in this regulator do es provide limited
downstream overpressure protection, but it should not be
considered complete overpressure protection. Refer to the
capacity information section to determine the required relief
valve capacity.
Q = P C
g
* 1.29
C
g
= See Table C
C
1
= See Table C
G
= gas specifi c gravity (air = 1.0)
P
= inlet pressure, psia
Q =
fl ow rate, SCFH
T
= absolute temperature of gas at inlet in ºRankine
P
= diff erential pressure, psi
(The diff erence between the
regulator inlet pressure and the maximum outlet pressure
that can be tolerated by downstream components)
Table B. 7337A-3 Regulator Springs
‡ Within a grouping, by changing compression springs, the "B" regulator may be made into either of two regulators above it; and those two above may
be changed into each other, but they cannot be changed into "B" regulators because they lack the high pressure diaphragm head assembly.
* Droop is the diff erence between outlet pressure selected and that realized when operating at maximum capacities listed in this table.
CAPACITY INFORMATION
T
able D provides the natural gas regulating capacities of the
7337A-3 regulators at specifi c inlet pressures and outlet pressure
settings. Flows are in SCFH (60°F and 14.7 psia)
of 0.6 speci
fi
c
gravity gas.
For specifi c gravity conversion factors to other gases,
refer to the "Selection Section".
To determine wide-open fl ow capacity of regulator for relief siz-
ing, use the following formula.
For critical fl ow: (P outlet absolute ≤ ½ P inlet absolute)
For subcritical fl ow: (P outlet absolute > ½ P inlet absolute)
Q = C
g
P
sin
√
520
GT
√
(
)
P
P
3417
C
1
7337A-3-GYS, 7337A-3-GYS-SS
8-12"w.c.
Purple
R690-5305
2"w.c.
11-18"w.c. 16-14"w.c.
7337A-3-GNS, 7337A-3-GNS-SS
1½ " NPT
14-30"w.c.
Dk. Green R690-5304
3"w.c.
7-28"w.c.
8-16"w.c.
7337A-3-BS, 7337A-3-BS-SS
‡
1.0-2.5 psig Blue
R690-5303
5"w.c.
7-56"w.c.
7-28"w.c.
7337A-3-2538, 7337A-3-2538-SS
‡
2.5-5.5 psig Yellow
R690-5322
5"w.c.
7-69"w.c.
1-2 psig
7337A-3-LGY, 7337A-3-LGY-SS
8-12"w.c.
Purple
R690-5305
2"w.c.
11-18"w.c.
6-14"w.c.
7337A-3-LGN, 7337A-3-LGN-SS
1½ " NPT
14-30"w.c.
Dk. Green R690-5304
3"w.c.
7-28"w.c.
8-16"w.c.
7337A-3-LB, 7337A-3-LB-SS
‡
1.0-2.5
psig
Blue R690-5303
5"w.c.
7-56"w.c.
7-28"w.c.
7337A-3-2534, 7337A-3-2534-SS
‡
2.5-5.5 psig Yellow
R690-5322
5"w.c.
7-69"w.c.
1-2 psig
7337A-3-LGY1, 7337A-3-LGY1-SS
8-12"w.c.
Purple R690-5305
2"w.c.
11-18"w.c. 6-14"w.c.
7337A-3-LGN1, 7337A-LGN1-SS
1½ " NPT 14-30"w.c. Dk.
Green
R690-5304
3"w.c. 7-28"w.c. 8-16"w.c.
7337A-3-LB1, 7337A-3-LB1-SS
‡
1.0-2.5
psig
Blue R690-5303
5"w.c.
7-56"w.c. 7-28"w.c.
7337A-3-2510, 7337A-3-2510-SS
‡
2.5-5.5 psig Yellow
R690-5322
5"w.c.
7-69"w.c.
1-2 psig
Regulator
Designation
End
Connections
Outlet
Pressure
Range
Compression Spring
Color
Number
Droop *
Approx. point above pres-
sure setting @ which inter-
nal relief starts to discharge
7337A-3_
7337A-3_-SS
Installation | High Pressure Gas Regulator
