Advertisement
WARNING
SERIOUS INJURY TO PERSONNEL AND/OR DAMAGE TO EQUIPMENT MAY OCCUR IF
SYSTEM OR COMPONENT DESIGN PRESSURE IS EXCEEDED. SHOULD THERE BE ANY
DOUBT AS TO THE PRESSURES LIKELY TO BE GENERATED IN THE SYSTEM WITH AN
INOPERATIVE OR INCORRECTLY SET BYPASS VALVE, PLEASE CONTACT EBSRAY FOR
MORE INFORMATION.
NOTE
In order to set the bypass valve, a throttling valve must be located in the discharge line
downstream of the bypass valve. A pressure gauge must be installed in the discharge line
between the pump and the throttling valve.
6.1 ADJUSTMENT PROCEDURE
1.
First open the throttling valve and any other
valves in the discharge line in order to minimise
the discharge pressure as much as possible.
Failure to do this could cause excessive and /or
dangerous pressures to be generated.
2.
Before starting the pump, loosen the locknut on
the bypass valve adjusting screw and screw the
adjusting
screw fully in
increases the tension on the spring and is the
maximum pressure setting for the particular
spring as fitted. [A number of springs are
available to give different pressure ranges]
3.
Start the pump and slowly close the throttling
valve
(ensuring
operating pressure is not exceeded) until the
pressure gauge shows expected bypass valve
cracking pressure. (Also called 'set pressure')
Now turn the adjusting screw out (anticlockwise)
until the gauge registers a slight drop in
pressure. At this point the bypass valve has
begun to open ie. cracking. Screw in the
adjusting screw one turn (clockwise) and then
tighten the locknut. The Bypass Valve is now set
6.2 VERIFICATION OF ADJUSTMENT
Re-open the throttling valve. Stop pump then
restart pump. Observe the pressure gauge whilst
again slowly and cautiously closing the throttling
valve. The gauge should register a levelling off
(or reduction) in the characteristic pressure rise
once the bypass valve cracking pressure has
been reached.
6.3 IMPORTANT NOTES
1.
The Bypass Valve is only one item controlling
pressure-rise in the bypass system. Other
valves, fittings and pipework downstream of the
bypass valve also cause system resistance, this
may affect maximum system pressure.
2.
Bypass valves only control differential pressure -
not total system pressure.
SECTION 6 - NOTES ON SETTING AND OPERATION
(clockwise).
This
pump/system
maximum
Typical Bypass Valve Characteristics
1
Cracking pressure (set pressure) (Where valve
starts to bypass)
2
Maximum pressure (At the rated operating
parameters)
3
Full flow pressure (bypass) (At the rated
operating parameters)
NOTE: Any pressure rise (or fall) after the cracking
point may depend upon:
a.
Flow
rate
(Excessive
restrictions in pipework, fittings etc.)
b.
Viscosity of product at pumping temperature.
c.
Specific bypass valve design and size.
The graph represents three typical bypass valve
characteristics. Actual performance during operation
will depend on bypass valve design, system design
and may also be affected by the parameters (a. b. &
c.) as listed above.
5
through
the
bypass
pressure
rise
may
valve.
signify
Advertisement
