MKS HPS LPV1-25-AC Series, Руководство по эксплуатации и обслуживанию

Страница: 31 / 52

23
HPS HPS
HPS HPS
HPS
®
Square Body LoPro Square Body LoPro
Square Body LoPro Square Body LoPro
Square Body LoPro
Seri es Seri es Seri es Seri es Serie s
7.2 Actuator Assembly – Pneumatic Version
7.2.1 Actuator Assembly Removal and Disassembly
The following procedure does not require removal of the valve body
from the system. However, several aspects of the procedure are
more easily performed if the entire valve is removed. Read section
7.1.1 prior to removing the entire valve or a valve’s actuator
assembly from a vacuum system.
The actuator assembly is attached to the bonnet of the valve by four bolts.
To remove the actuator assembly, simply loosen and remove these four
bolts. After the bolts are removed, carefully pull the actuator assembly out
of the valve body. The bellows is fabricated of .006" thick 321 stainless
steel. While withdrawing the actuator assembly, exercise care to avoid
damaging the bellows. If the bonnet o-ring has adhered to the sealing
surface in the body carefully remove it by hand. If a tool is required for this
task, it should be made of a material softer than stainless steel to avoid
scratching the sealing surface.
The actuator assembly contains a powerful spring under some compression
at all times. A special fixture is required for further, safe disassembly of the
actuator. Replacement of malfunctioning actuators with new assemblies is
recommended (see parts list in section 7.6 for details).
7.2.2 O-Ring Replacement
The bonnet o-rings may easily be removed without a special fixture. With a
little stretch, the bonnet o-ring clears the bellows and drops off of the
actuator assembly.
Removal of the nosepiece o-ring usually requires a thin tool to pry it out of
its trapezoidal groove. Exercise care to avoid damaging the sealing surface
at the bottom of the groove. Start prying at the vent hole and carefully move
around far enough to allow grasping the seal with the fingers. Then pull the
seal from the remainder of the groove.
Be sure that no dust or other contamination is in the groove or on the o-ring.
To install the o-ring, nest the o-ring on the opening of the groove. With the
thumbs at points 180
o
apart, firmly press the o-ring into the groove. Move
90
o
and press again. Move 45
o
and press again. Alternately press the o-ring
into the groove until it is completely in the groove. Hand installation will
likely leave humps on the installed o-ring. As long as the o-ring has not
twisted during assembly, this will disappear after a small number of cycles,
after which the valve should function properly.