Singer Valve 106-PR-48 Installation, Operating And Maintenance Instructions

Pressure Reducing Valve with Direct Acting Low Flow By-Pass

DESCRIPTION:

Model 106/206-PR-48 is a pilot operated pressure
reducing valve designed to automatically reduce a
high inlet pressure to a lower outlet pressure. The
valve will maintain a relatively steady downstream
pressure regardless of fluctuations in the supply
pressure or flow rate.
Main Valve (1) is pilot operated . For
stability, a ¾" direct acting Pressure Reducing Valve
(9) is piped in parallel to the Main Valve. The
standard configuration is to have the by-pass valve
piped into the ports on the opposite side of the pilot
system.
Unless otherwise specified, the valve will be
assembled for service temperatures to 180 deg. F (80
deg.C).

DESCRIPTION OF OPERATION:

Main Valve (1) is normally open when pressure is
applied to the valve inlet. When the same pressure is
applied to the bonnet, the valve closes tight. Refer to
106/206-PG 'Description of Operation'. By controlling
the pressure in the bonnet, the Main Valve can be
made to open fully, close tight or open partially.
The bonnet pressure (and therefore the position of the
Main Valve) is controlled by a pilot circuit consisting
of Fixed Restriction (4), Flow Stabilizer (5) if so
equipped and Pressure Reducing Pilot (7).
When there is no demand (and the downstream
pressure is at the setting of Pilot [7]), Pressure
Reducing Pilot (7) is closed. Pressure from the inlet
side of the Main Valve is directed to the bonnet
through the Fixed Restriction (4) and the Flow
Stabilizer (5), if so equipped. The Main Valve closes.
When flow is required, Pilot (7) senses a drop in the
downstream pressure and opens. Flow through Pilot
(7) is greater than flow through Fixed Restriction (4).
Bonnet pressure is reduced and Main Valve (1) opens
to supply the demand. Speed of opening is de-
termined by the setting of Flow Stabilizer (5), if so
equipped. Refer to Model 26 instructions for details
and adjustment.
Under flowing conditions, Pilot (7) reacts to small
changes in pressure to modulate the bonnet pressure
(and valve position) as required to keep the
downstream
SINGER MODEL 106/206-PR-48
Schematic A-8063E
Installation, Operating and Maintenance Instructions
low flow
IOM A-8063E Page 1 of 2
pressure constant. Note that Main Valve position
follows the position of Pilot (7). When Pilot (7) closes,
the Main Valve closes. When Pilot (7) opens, the
Main Valve opens.
Direct acting Pressure Reducing Valve (9) is normally
held open by the internal spring. Downstream
pressure acting on the diaphragm is opposed by the
spring force. When the downstream pressure acting
on the diaphragm area exceeds the spring force, the
valve closes. Being a direct acting valve, this valve
operates 'instantly' and is very stable.

INSTALLATION:

1. Refer to 106/206-PG 'Installation'.
2. Installation where there is loosely held piping
and/or elbows close to the valve may cause the
valve to pulsate.

ADJUSTING PROCEDURE:

PILOT OPERATED MAIN VALVE ;
1. Open Isolating Valves (2), (6) and (8).
2. Crack outlet stop valve and slowly open inlet stop
valve wide.
3. Bleed air from Main Valve bonnet. SEE 106/206-
PG 'INSTALLATION'.
4. Open outlet stop valve wide.
5. Close Isolating Valve (10).
6. Set reduced (downstream) pressure approximately
5 psi lower than the desired low flow pressure, by
turning Pilot (7) adjusting screw: To increase
pressure, turn adjusting screw clockwise. - To
reduce pressure,
counterclockwise.
7. NOTE THAT THERE
THROUGH THE VALVE WHEN PRESSURE IS
ADJUSTED.
8. IF THE VALVE DOES NOT OPEN (pressure
remains low), check the adjustment of Flow
Stabilizer (5), if so equipped. SEE MODEL 26
INSTRUCTIONS.
9. IF THE VALVE BEGINS TO OSCILLATE OR
HUNT:
•
Bleed air from Main Valve bonnet. SEE 106-
PG/206-PG 'INSTALLATION'.
•
Adjust Flow Stabilizer (4), if so equipped. SEE
MODEL 26 INSTRUCTIONS.
January 2008
th
12850-87
Surrey, BC. Canada. V3W 3H9
Ph: 604-594-5404
Fx: 604-594-8845
www.singervalve.com
turn adjusting screw
MUST BE FLOW
Avenue