Emerson Yarway 9200 Series Installation And Maintenance Instructions

YarwaY 9200 SerieS ArC
InstallatIon and maIntenance InstructIons
Before installation these instructions must be fully read and understood
GENEral
These sizes in the 9200 ArC
®
recirculation Control) valve series are designed
to provide protection for low to moderate
pressure (ASMe/AnSi 150 and 300 Class)
centrifugal pumps against overheating and
possible unstable operation during low load
periods. The valve functions simultaneously
as (1) a check valve - to prevent reverse flow
through the pump and as (2) a bypass control
valve - to maintain the minimum required
pump flow and provide pressure letdown.
valves.emerson.com
VAlVeS 2", 3" And 4"
®
OpEratION
Flow through the check valve overcomes the
spring force to open the main check valve
element. When the disc lifts in response to
an increase in main flow, the bypass flow is
decreased as the port openings in the disc stem
begin to close. Conversely, as the pump flow is
reduced, the check disc moves downward and
at a designated point starts to uncover the disc
stem ports allowing bypass flow to begin.
The sizing of the main check/trim is such that
the bypass flow starts before the main flow
drops below the minimum pump flow specified.
The combined main and bypass flows provide
a total greater than the minimum pump flow
requirement.
Bypass flow enters the disc stem passage
through the slots and the round ports and
(Automatic around the annulus in the bypass bushing. it
then continues through the bypass where the
helix element conditions the flow at the valve
bypass outlet. The recirculation flow rate is
controlled by the disc slot sizing. Occasionally
higher pressure applications may require the
use of a Back Pressure regulator (BPr) in the
bypass line for proper pressure letdown.
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engineering doc. #972562 rev. A
VCIOM-03341-EN 17/05