Singer Valve 106-PR-48, 206-PR-48 Installation, Operating And Maintenance Instructions
SINGER MODEL 106/206-PR-48
Pressure Reducing Valve with Direct Acting Low Flow By-Pass
Schematic A-8063E
Installation, Operating and Maintenance Instructions
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 low flow
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 determined 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
IOM A-8063E Page 1 of 2 January 2008
Surrey, BC. Canada. V3W 3H9
www.singervalve.com
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, turn adjusting screw
counterclockwise.
7. NOTE THAT THERE MUST BE FLOW
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 106PG/206-PG 'INSTALLATION'.
• Adjust Flow Stabilizer (4), if so equipped. SEE
MODEL 26 INSTRUCTIONS.
12850-87th Avenue
Ph: 604-594-5404
Fx: 604-594-8845
Adjusting Procedure (Cont.):
BY-PASS VALVE ;
1. Open Isolation Valve (10).
2. Close Isolating Valve (8) and leave Isolating
Valves (2) and (6) open.
3. There must be flow through the valve for the
pressure to be adjusted.
4. Set reduced (downstream) pressure at the desired
low flow setting (approximately 5 psi higher than
Main Valve setting). To increase pressure, turn
adjusting screw clockwise. - To reduce pressure,
turn adjusting screw counterclockwise.
IOM A-8063E Page 2 of 2 January 2008
Surrey, BC. Canada. V3W 3H9
12850-87th Avenue
Ph: 604-594-5404
Fx: 604-594-8845
www.singervalve.com
SERVICE SUGGESTIONS:
In addition to service suggestions listed in the 106PG/206-PG instruction, we suggest the following:
IF THE MAIN VALVE FAILS TO CLOSE:
Close Isolating Valve (10). Close Isolating Valve (8) .
If the Main Valve closes, Pilot (7) is defective. If the
valve does not close, close Isolating Valve (2).
Remove the copper tube between Fixed Restriction
(4) and Flow Stabilizer (5), if so equipped. If there is
continuous flow from Flow Stabilizer (5), Main Valve
diaphragm is ruptured. If there is no continuous flow
from Flow Stabilizer (5), open Isolating Valve (2)
slowly. If there is no flow, Strainer (3) is plugged.
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