Standard Components
Operation
The On-Off Float Control Valve with Pressure Sustaining Feature
is designed to open fully or close drip-tight as commanded by the
Float Control Pilot. The Float Pilot may be either valve or remote
mounted. The valve closes drip tight when water level reaches the
adjustable high-level setpoint, and opens fully when water level
is below the adjustable low-level setpoint, allowing a calculated
“draw-down” of water level to increase tank circulation. The valve
will also throttle to sustain a minimum upstream pressure during
tank filling operations.
The On-Off Float Pilot directs upstream pressure into and out
of the cover chamber of the 3-way Accelerator Pilot. When the
cover of the Accelerator Pilot is pressurized, the main valve cover
chamber is vented downstream, causing the valve to open. When
the cover of the Accelerator Pilot is de-pressurized, the main valve
cover chamber is connected to upstream pressure, causing the
valve to close drip tight. Valve opening and closing speeds are
separately adjustable. When water level reaches the adjustable
high-level setpoint, the Float Pilot de-pressurizes the cover cham-
ber of the 3-Way Accelerator, closing the valve drip tight.
1
X
X
Y/FC
3
2
5
6
X
4A
4B
P/L
CLOSES VALVE
OPENS VALVE
FLOW
(AOS)
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. 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 horizon-
tal 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 order-
ing 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 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.
6. Install a pressure gauge at a location upstream of the valve.
7. Install float control onto tank and connect lines to valve per Watts Model F10-13 Specification Sheet.
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.
The valve remains closed as water level decreases. When water
level reaches the adjustable low-level setpoint, the Float Pilot
pressurizes the cover chamber of the 3-Way Accelerator, open-
ing the valve. High and low levels are separately adjustable by
positioning stop collars on the float rod(s) at desired opening and
closing setpoints.
The normally closed sustaining pilot remains open when upstream
pressure is above the adjustable setpoint, and modulates toward
a closed position if upstream pressure falls below the setpoint.
As the sustaining pilot closes, fluid is directed into the main valve
cover chamber, allowing the valve to modulate toward a closed
position, raising upstream pressure. Normal on-off float control
operation resumes when upstream pressure is above the sustain-
ing pilot setpoint.
1 – Main Valve (905GD – Single Chamber)
2 – Model 22 Accelerator Control
3 – On-Off Float Control
4A – High Level Adjustment Stop
4B – Low Level Adjustment Stop
5 – Adjustable Closing Speed
6 – Pressure Sustaining Control
X – Isolation Cocks
Installation
972GD-20 (Globe) On-Off Float Control Valve with Pressure
Sustaining Feature
2 IOM-A-ACV-972-20_672-20 2115
EDP# 1917112
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