981GD (Globe) Pump Control Control Valve with Pressure
Reducing Feature
2 IOM-A-ACV-981_681 2115
EDP# 1917096
© 2021 Watts
Standard Components
1
X
X
Y/FC
2
3(L)
4
5
5
6
7
8
X
X
CLOSES VALVE
OPENS VALVE
FLOW
Installation
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.
3. Install isolation valves upstream and downstream of the main valve.
4. Provide adequate clearance for valve servicing and maintenance. Refer to valve servicing dimensions on next page. Avoid installing valves
6" and larger in the vertical position (main valve stem horizontal). Automatic Control Valves (ACVs) are designed for horizontal in-line instal-
lation, 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.
5. If valve is equipped with a pilot control system, extra precautions should be made during installation to protect the piping circuit from dam-
age. 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.
6. Connect solenoid wiring leads to desired switching device, using safe, standard electrical practices.
7. Wire the limit switch contacts to the proper relay connections, using safe, standard electrical practices. Adjust the limit switch collar to the
approximate make/break contact position.
8. After installation, vent entrapped air from valve cover and pilot system by following instructions on Technical Bulletin.
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.
Operation
The Pump Control Valve with Pressure Reducing Feature is designed
to minimize the surges associated with the starting and stopping of
pumps. The valve slowly opens and closes as required to control
pumping related surges, and throttles to maintain a maximum down-
stream pressure during the pumping cycle. The pump starts and stops
against a closed valve.
Pump Start Up:
When the pump is signaled to start, the 3-Way So-
lenoid is energized, directing pressure into the cover chamber of the
3-way Accelerator Pilot. The Accelerator Pilot allows the main valve
cover chamber to be vented downstream, causing the valve to open
at a controlled rate, gradually admitting pumping pressure into the dis-
tribution system. The rate of opening is controlled by the adjustable
opening speed control, which restricts the speed of fluid and pressure
evacuating the main valve cover chamber.
Pressure Reducing Feature:
During the pumping cycle, the valve acts
as a Pressure Reducing Control Valve. Throttling (Pressure Reducing)
action is controlled by a normally open, pressure reducing pilot de-
signed 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 through the
integral orifice of the Accelerator Pilot) when downstream pressure is
above the adjustable setpoint. A decrease in downstream pressure
causes the valve to modulate toward an open position, raising down-
stream pressure. An increase in downstream pressure causes the valve
to modulate toward a closed position, lowering downstream pressure.
Pump Shutdown:
When the pump is signaled to turn off, the 3-Way
Solenoid is de-energized, venting the cover chamber of the 3-way Ac-
celerator Pilot. The Accelerator Pilot allows the main valve cover cham-
ber to be connected to upstream pressure, causing the valve to close
at a controlled rate. The valve slowly begins to close while the pump
continues to operate. The closing rate of the valve is controlled by
the adjustable closing speed control, which restricts the speed of fluid
and pressure entering the main valve cover chamber. When the valve
reaches the closed position, the limit switch is actuated, turning the
pump off.
Hydraulic Check Feature:
When the pump is turned off and down-
stream pressure is greater than upstream pressure, downstream pres-
sure is admitted to the main valve cover chamber through a check
valve in the pilot control system, closing the valve, preventing reversal
of flow.
Manual Operation:
Engaging the Solenoid Manual operator simulates
power to the solenoid, manually opening the main valve. Disengaging
the Solenoid Manual operator returns the valve to the closed position.
1 – Main Valve (905GD – Single Chamber)
2 – Model 22-1 Accelerator Control
3 – Limit Switch
4 – 3-Way Solenoid
5 – Check Valve
6 – Adjustable Opening Speed
7 – Adjustable Closing Speed
8 – Pressure Reducing Control
Y – Y-Strainer
X – Isolation Cocks
