North American High Pressure Regulators
and Relief Valves
Ref: Bulletin 7337A-3, 7337A/B/C-4, 7337-4 and 7347
Make sure all piping is clean before installing regulator(s). Blow
out piping if necessary before installing components.
Inspect regulator for damage and make sure the valve disc and
seat are clean.
It is preferable, but not necessary, that
Coat male pipe threads lightly with pipe joint compound (ex-
cess can migrate to the valve seat and aff ect operation). If using
Tefl on tape, do not wrap the fi rst two threads (avoid using tape at
all if possible).
Install unions on both the inlet and outlet of the regulator to
facilitate repair or replacement if necessary.
If uninterrupted operation is necessary in the event of a regula-
tor failure, install two regulators in parallel. Each regulator will
require manual shutoff valves on both inlet and outlet.
337-4 Regulators (see Figure 1)
The downstream pipe size, should be increased as close to the
regulator outlet as possible. A reducing coupling must be used,
not a bushing.
Measuring 10 pipe diameters downstream of the outlet of the
educing coupling, on the top or side of the pipe, provide a con-
nection for a pressure sensing line (see Fig. 1). This connection
must be in a straight length of pipe, and not aft er elbows or any
other fi ttings. Using
" pipe, connect the underside of the
regulator diaphragm case to this connection.
Install an 1837D-01 Needle Valve in the pressure sensing line to
provide means for pulsation dampening. This valve has an inter-
nal orifi ce which prevents shutoff . DO NOT use a conventional
needle valve which can completely shut off the downstream
signal and result in a dangerous condition.
7337A-3 and 7347 Regulators
The regulator outlet pipe size must be maintained for 10 pipe
diameters before increasing the size. The 7337A-3 piping may
then be increased. The 7347 piping may then be increased one
pipe size only.
The 7337A-3 and 7347 Regulators MUST NOT be cross-connect-
ed to the air line. To do so will create a hazardous condition
because they have internal relief valves.
The 7337-4 Regulator vent may be cross-connected to the com-
bustion air line downstream of the combustion air control valve
for the following reasons:
1) To permit functioning as a ratio regulator.
2) To provide a constant pressure drop across a downstream
cross-connected ratio regulator. (Provides more accurate con-
trol especially on turndown.)
When cross-connecting 7337-4L-1 and -2 Regulators, remove and
discard the snap-ring and fl apper valve inside the regulator vent
Y | C