Ebsray HD600, Инструкция по установке, эксплуатации и обслуживанию, Страница: 8 / 11

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SECTION 5 - INTEGRAL BYPASS VALVES
5.1 GENERA L
This Bypass Valve is intended for integral installation in
EBSRAY's Internal Gear Pumps. The valve is mounted
in such a manner as to return liquid from the discharge
side of the pump to the inlet side of the pump when
differential pressure reaches or exceeds a preset level.
The Bypass Valve is mounted with the Adjusting Screw
pointing toward the inlet chamber of the pump.
5.2 OPERATION
The BYPASS VALVE is spring loaded and adjustable
within a pressure range determined by the actual spring
used. EBSRAY can supply a variety of springs to suit
varying differential pressures. They are designed for
liquid service and to provide pump and drive protection
from excessive differential pressures above specified
duty point parameters.
Upon commissioning, the Bypass Valve should be
adjusted in accordance with the predetermined pump
differential pressure required.
5.3 MAINTENANCE
PRIOR TO ANY DISASSEMBLY OR SERVICE,
VERIFY THAT ALL REQUIREMENTS OF STATUTORY
REGULATIONS OR CODES ARE MET
AND THAT
SPECIFIC SITE REQUIREMENTS ETC. ARE
SATISFIED.
Apart from Bypass Valve Body replacement, other
maintenance tasks and inspections can be carried out
with the Bypass Valve fixed to the pump Cover, so long
as complete isolation, depressurising and purging have
been completed.
5.4 DISASSEMBLY
1. Remove Adjusting Screw Cap.
2. Unlock Adjusting Screw Locknut.
3. Release spring pressure by rotating Adjusting
Screw anti-clockwise.
4. Remove the four Setscrews, affixing the Bypass
Valve Cap onto the Bypass Valve Body.
5. Remove the Cap assembly complete with Adjusting
Screw, Locknut and Gasket.
6. Remove Adjusting Screw and Llocknut from Cap.
7. Remove Spring Cap, Valve Spring and Valve from
Body.
5.5 INSPECTION
1. Inspect Bypass Valve Body, particularly valve seat,
for damage or wear. If required remove Bypass
Valve Body and re-machine or replace.
2. Check Valve for damage or deposits. Clean
thoroughly or replace Valve as required. If worn, or
if seat or Valve is damaged, lap cleaned/replaced
Valve into valve seat.
3. Inspect Bypass Valve Spring. Replace if broken or
damaged.
4. It is advised that all gaskets be replaced whenever
disassembled.
5. Check Cap, Washer, Adjusting Screw and Locknut
for damage. Replace as required.
5.6 REASSEMBLY
(Refer Drg No. CMP051)
1. Screw Locknut onto Adjusting Screw and then
screw Adjusting Screw into Cap.
2. Fit Valve into Body, ensuring freedom of
movement.
3. Fit Spring on to top of Valve.
4. Fit Spring Cap to Spring.
5. Fit Gasket to Cap, position Cap on Body ensuring
that the Adjusting Screw locates in the hole in the
Spring Cap.
NOTE This may be achieved easily by screwing the
Adjusting Screw all the way in for positioning
and then backing off the Adjusting Screw to
position and tighten the Setscrews.
6. Fasten Cap to Body by means of four Setscrews.
5.7 ADJUSTMENT
NOTE: Final adjustment is carried out after the valve is
mounted on the pump installed.
1. For increased bypass pressure, rotate Adjusting
Screw in clockwise direction ( i.e.screw in ).
DO
NOT exceed pump or system design pressure.
2. For decreased bypass pressure, rotate Adjusting
Screw anti-clockwise (i.e. screw out).
3. Lock Adjusting Screw Lock Nut against Cap
immediately after any adjustment is made.
4. After Adjstment is completed, fit Adjusting Screw
Cap and Gasket.
NOTE: Bypass valves characteristically exhibit three
distinct differential pressures during their
operation :
a) The set or 'cracking' pressure which occurs
when product initially begins to be bypassed
against the preset spring load.
b) Maximum differential pressure, which occurs
when the flow of the bypassed product passes
through the bypass valve.
c) Full flow differential pressure which occurs
when all the product being pumped passes
through the Bypass Valve.
It is important to ensure the above characteristics are
understood fully in order to correctly apply and adjust the
Bypass Valve in a given system.