Standard Components
Operation
The Combination Pressure Reducing and Surge Automatic Control
Valve (ACV) is designed to automatically reduce a fluctuating higher
upstream pressure to a constant lower downstream pressure, and
will quickly modulate toward a closed position if downstream pres-
sure suddenly becomes greater than the desired regulated setpoint.
The quick closing action prevents possible damaging high inlet
pressure from passing through the valve to downstream piping.
Normal regulating action is controlled by a normally open, pressure
reducing pilot designed to: 1) Open (allowing fluid out of the main
valve cover chamber) when downstream pressure is below the
adjustable setpoint, and 2) Close (allowing fluid to fill the main valve
cover chamber) when downstream pressure is above the adjustable
setpoint. A decrease in downstream pressure causes the valve to
modulate toward an open position, raising downstream pressure.
An increase in downstream pressure causes the valve to modulate
toward a closed position, lowering downstream pressure.
If downstream pressure suddenly becomes greater than the
desired regulated setpoint, the normally closed surge control pilot
opens and rapidly admits higher inlet pressure into the valve cover,
increasing rate of valve closure. Normal pressure reducing opera-
tion resumes when downstream pressure decreases below the
desired regulated setpoint.
1
X
X
X
X
Y/FC
P/L
2
3
4
CLOSES VALVE
OPENS VALVE
FLOW
4
CLOSES VALVE
OPENS VALVE
FLOW
AOS
Start-up of an automatic control valve requires that proper procedures be followed. Time must be allowed for the valve to react to
adjustments and the system to stabilize. The objective is to bring the valve into service in a controlled manner to protect the system
from damaging over-pressure.
1. Prior to installation, flush line to remove debris.
2. Install valve so the flow arrow matches flow through the line, and gauges to monitor valve inlet and outlet pressures. A Position
Indicator can be installed to provide visual indication of valve position and operation without disassembly.
3. Install isolation valves upstream and downstream of the main valve.
4. Open the isolation ball valves in the control tubing if so equipped. Failure to open these will prevent the valve from functioning
properly.
Note:
If using butterfly valves, ensure valve disc does not contact the main valve.
5. Provide adequate clearance for valve servicing and maintenance. Refer to valve servicing dimensions on next page.
6. Avoid installing valves 6" and larger in the vertical position (main valve stem horizontal). Automatic Control Valves (ACVs) are
designed for horizontal in-line installation, with the cover facing up (main valve stem vertical). Slow operation or premature stem
and guide wear may occur if valve is not installed according to factory recommendations. Consult factory for detailed engineering
review prior to ordering if valve is to be installed other than horizontally in-line.
7. If valve is equipped with a pilot control system, extra precautions should be made during installation to protect the piping circuit
from damage. Only remove the pilot control system from the valve if necessary. Tubing and fittings should be kept clean and
replaced exactly as removed. Consult appropriate hydraulic schematic to ensure proper re-assembly.
8. After installation, vent entrapped air from valve cover and pilot system by following instructions on Technical Bulletin.
1 – Main Valve (905GD – Single Chamber)
2 – Pressure Reducing Control
3 – Downstream Surge Control
4 – Fixed Orifice
X – Isolation Cocks
Installation
910GD-11 (Globe) Pressure Reducing Control Valve with
Downstream Surge Control Feature
2 IOM-A-ACV-910-11_610-11 2115
EDP# 1917042
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