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 The
Model 735 Surge Anticipating Control Valve is an automatic
control valve designed to protect pumps and pipelines from pressure
surge damage resulting from the sharp flow velocity changes
associated with pump starting and stopping and especially with
abrupt pump stoppage caused by power failures.
It is a pilot controlled, hydraulically operated, diaphragm
actuated globe valve in either the oblique (Y) or angle pattern
design. Valve differential pressure powers the diaphragm actuator
open or closed.
The lower control chamber is connected through a fixed orifice
to the downstream pressure, which serves to cushion the closing
of the valve.
The upper control chamber, which operates on a two-way control
principle, has varying pressure produced by the regulating pilots
and the relief pilot's internal upstream restriction needle
valve.
 The
abrupt stopping of a pump will generally produce a drop in pressure
followed by a high pressure surge The low pressure relief pilot
senses this initial drop in pressure and opens allowing the
main valve to open in anticipation of the returning high surge.
The open main valve relieves the high pressure surge to atmosphere.
The high pressure relief pilot sensing this same high surge
also opens to maintain the main valve in the open position.
A hydraulic or mechanical flow control limits the opening of
the valve. This device effectively controls the surge relief
and ensures the main valve closing without excess waste of system
pressure. As this high pressure dissipates and approaches the
set point, the high pressure relief pilot regulates to close,
the pressure in the upper control chamber begins to increase
and the main valve modulates closed allowing system pressure
to increase to the preset pressure setting.
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Valve Line Up
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