Ames Fire & Waterworks 979GS-20 Stainless Steel Modulating Float Valve with Pressure Sustaining Feature - Manual

01/06
970 Series Model
8550 Hansen Road • Houston, Texas 77075 • (Ph) 713.943.0688 • (Fx) 713.944.9445 • www.amesfirewater.com
MODULATING FLOAT VALVE with
PRESSURE SUSTAINING FEATURE
979-20
679-20
Operation
The AMES Model 979-20 / 679-20 Modulating Float Control Valve with Pressure Sustaining Feature is
designed to automatically maintain a constant liquid level in a tank or reservoir. It is controlled by a remote
mounted Modulating Float Pilot designed to: 1) Modulate Open (allowing fluid out of the main valve cover
chamber) when reservoir level decreases, and, 2) Modulate Closed (allowing fluid to fill the main valve
cover chamber) when reservoir level increases. A decrease in reservoir level causes the valve to modulate
towards an open position, allowing reservoir level to increase. An increase in reservoir level causes the
valve to modulate towards a closed position, allowing reservoir level to decrease.
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 level control operation resumes when upstream pressure is
above the sustaining pilot setpoint.
If desired, the modulating action of the valve can be “reversed” by inverting or “reversing” the action of
the Modulating Float Pilot. The Modulating Float Control is remotely mounted from the valve, and field
connected with 3/8” minimum copper tubing in accordance with factory piping schematic.
Installation Guidelines
• Prior to installation, flush line to remove debris.
• Install valve horizontally “in line” (cover facing up), so flow arrow matches flow through the line. Avoid
installing valves 6” and larger vertically. Consult factory prior to ordering if installation is other than
described.
• Install inlet and outlet isolation valves. NOTE: When using butterfly valves, insure disc does not contact
control valve. Damage or improper valve seating may occur.
• Provide adequate clearance for valve servicing and maintenance.
• Install pressure gauge to monitor valve inlet pressure.
• Connect Modulating Float Control to main valve using 3/8” diameter minimum copper tubing (field
installed) in accordance with factory piping schematic.
• Modulating Float Control should be mounted in a field installed “stilling well” for protection against surface
turbulence and interference.
Other AMES Float Control Valves
972 / 672 On-Off Float Control Valve (4” & smaller)
972-19 / 672-19 On-Off Float Control Valve (6” & larger)
972-20 / 672-20 On-Off Float Control Valve with Pressure Sustaining Feature
979 / 679 Modulating Float Control Valve
979-15 / 679-15 Modulating Float Control Valve with Solenoid (On-Off) Feature