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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.

engineering doc. #972562 rev. A

VCIOM-03341-EN 17/05