1. Basic details of PRS
• Not required any external source
of power to function
• Pressure from the fluid on the
diaphragm - activates the
open/close action of the valves.
•
•
•
•
High accuracy , High rangeability , Large flow
Tight shut off capability
Easy ,Fast & inexpensive maintenance
Low noise level
Slam Shutoff
• The control mechanism is having
latching arrangement that hold
the main valve stem in open
position.
• The sensing element is pilot
regulator
(Pilot)
which
continuously monitors the line
pressure
which
is
to
be
safeguarded.
• This
pilot
is
spring
loaded
diaphragm type valve and incase
of over-pressurization it gives
pressure
signal
to
control
mechanism which in turn trips off
the main valve.
• The rack latched by the ball gets
released resulting in downward
movement of plug and plug rod by
closing the valve. The visual
indicator
will
indicate
the
position as “CLOSE”.
Valve
Pressure Regulator - Monitor valve (Fail
to Close)
• In the absence of
the
pressure
in
the
system,
the
valve is kept in
closed
condition
by the action of
spring,
which
keeps
the
valve
pressed
against
assembly.
• the
The plug
desired
control pressure is
adjusted through set screw of pilot.
• The plug rod is controlled by the
diaphragm on which the following
forces act
a) Downwards
:
spring
load
,
regulated pressure (Pa) in the
chamber ‘E’ & the weight of the
plug assembly.
b)
Upward
:
pressure(Pm) in the
Motorization
chamber ‘F’
Pressure Regulator – Active valve (Fail
to Open)
• If
there
is
no
pressure, the valve
is kept in a fully
open position by mean
of spring force.
• The
pressure
that
modify the main valve
position
&
thus
control flow, is feed
by the first stage of
pilot
that
reduces
the pressure slightly
higher
to
outlet
pressure
and
• communicate
Downwards (outlet this
pressure rises): Closing
pressure
directly
pressure(Pm)
in the to
chamber ‘E’ & the
the
pilot
input
weight
of the
plug and
assembly
main
regulator
• diaphragm.
Upwards (outlet pressure drops) : spring
load , Motorization pressure(Pm) in the
chamber ‘F’.
Typical installation of Active & Monitor
Configuration
• Monitor regulator
regulator.
is
installed
upstream
of
the
main
(active)
• The two regulators are virtually identical from the point of view of
their mechanical construction.
• Normally, Monitor remains wide open and Active regulator regulates
the outlet pressure at the set value.
• Monitor regulator takes over and regulates the controlled pressure at
its set value, which is marginally higher than that of Active