Ames Fire & Waterworks 920GS Stainless Steel Pressure Relief, Sustaining or Backpressure Control Valve - Manual

01/06
920 Series Model
8550 Hansen Road • Houston, Texas 77075 • (Ph) 713.943.0688 • (Fx) 713.944.9445 • www.amesfirewater.com
Operation
The AMES Model 920 / 620 Pressure Relief, Sustaining or Backpressure Control Valve is designed to permit
flow when upstream pressure is above the adjustable setpoint of the control pilot, and throttle toward closed
when upstream pressure falls below the adjustable setpoint. It is controlled by a normally closed control
pilot designed to: 1) Open (allowing fluid out of the main valve cover chamber) when upstream pressure
is above the adjustable setpoint, and, 2) Close (allowing fluid to fill the main valve cover chamber) when
upstream pressure is below the adjustable setpoint. An increase in upstream pressure causes the valve to
modulate toward an open position. A decrease in upstream pressure causes the valve to modulate toward
a closed position.
When the Model 920 / 620 is installed “off the main line” on the branch of a tee, it serves as a Pressure
Relief Control Valve. The 920 / 620 is normally closed, and quickly opens when upstream pressure
exceeds the pilot setting,
relieving pressure, commonly discharging to a storage reservoir, pump suction,
or atmosphere. When upstream pressure is lowered below the pilot setting, the valve closes at a controlled,
adjustable rate.
When the Model 920 / 620 is located “in line” connecting two distribution zones, the valve acts as a
Pressure Sustaining Control Valve. When pressure in the upstream zone falls below the pilot setting,
the valve modulates toward a closed position, sustaining pressure in the upstream zone. The valve will
close, if necessary, until upstream pressure is above the pilot setting. The valve should be specified to
include the optional opening speed control and position indicator when used for Pressure Sustaining
applications.
When the Model 920 / 620 is installed “in line” on the discharge of a pump, it acts as Backpressure
Control Valve. When pump discharge pressure falls below the pilot setting, the valve modulates toward a
closed position, increasing
backpressure against the pump. The valve should be specified to include the
optional opening speed control when used for Backpressure applications.
PRESSURE RELIEF, SUSTAINING, or
BACKPRESSURE CONTROL VALVE
920
620