Instructions 7337/7347

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 


" or 


" 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


Catalog Combustion 2021 - Page 1189

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Fives Group Part Numbers on this Catalog Page
Line Part Number Manufacturer Request Quote
1 7337a/b/c-4 Fives Group Request Quote
2 7337a-3then Fives Group Request Quote