Bell & Gossett HS 601G Pilot Operated Pressure and/or Temperature Steam Regulators Series 2000 User Manual

Page 6

10 Pipe

Diameters

Applies to All Pilots
1. The pilot valve(s) can be installed on either side of the

main valve. The main valve is shipped with the U-

tubing and the bleed orifice installed for left-hand side
mounting of the pilot valve(s). If right-hand side
mounting of the pilot(s) is desired, the U-tubing and
the bleed orifice must be relocated to the opposite
sides of the main valve.
Note: Right-hand side and left-hand side positioning is
determined when the main valve inlet directly faces
the observer.

2. Make sure the bleed orifice is installed in the 1/8 NPT

tapping on the outlet end of the main valve on the
opposite side from the U-tubing. Remove the 1/8 NPT
pipe plug from the bleed orifice and replace it with a
1/8 NPT x 1/4" (6mm) OD tubing, straight compression
fitting (from the hardware kit).

3. Install the 1/4 NPT x 1-1/2" (38mm) nipple and half of

the union connection (from the hardware kit) on the
inlet end of the main valve.

4. Use the 1/4 NPT x 4" (101mm) nipple and the remaining

half of the union connection (from the hardware kit) to
mount the first pilot. Mount additional pilots as
required using 1/4" steel pipe nipples.

5. Install the copper tee fitting (from the hardware kit) in

the 1/8 NPT signal tapping on the side of the last pilot
with the tee pointing down.

6. Install the L-fitting (from the hardware kit) in the tapping

at the center of the main valve diaphragm cover.
Note: For steps 7 and 8, trim the length of the copper
tubing as required (see "Tubing Length Chart", page
5) to make a neat installation. Be sure to ream the
tube to the full tube diameter after cutting.

7. Install the S- or J-copper tubing (from the hardware

kit) from the tee fitting to the bleed orifice.

8. Install the L- copper tubing (from the hardware kit)

from the bottom of the tee fitting to the L-fitting in the
main valve diaphragm cover.

Pilot Installation Detail

The function of the bleed orifice is to bleed steam off the
main valve diaphragm when the pilot(s) close(s). A 1/16"
(1.6mm) diameter orifice is standard, and is installed in
the outlet side of the main valve when shipped. This
diameter orifice is used in most applications.

In special situations, the bleed orifice may be drilled out
to 3/32" (2.4mm) diameter to produce faster closing time
of the main valve and thus improve response time.

• A 3/32 in. (2.4mm) diameter orifice should NOT be

used in conjunction with a temperature pilot, as
accuracy of temperature control will be reduced.

• Typical applications for 3/32 in (2.4mm) diameter

bleed orifice may include:
– Pressure differential across the reducing valve is

50 psig (3.5 bar) or greater.

– High pressure PRV on a 2-stage pressure

reducing station.

– Pressure reducing valve with a fast acting

pneumatic temperature regulator downstream
of the main valve.

Bleed Orifice