MKS HPS LPV1-25-AC Series, Operation And Maintenance Manual

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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 Seri es
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8.3.9 Stem seal failure – Pneumatic Actuation Only
The seals used on pneumatic stems are normally good for much more than
10
6 cycles. However, an occasional defect in the material, in the seal’s
installation, or inadequate lubrication could cause a bit of the edge of this
seal to break off, resulting in a pneumatic leak. Due to the special fixture
required to fully disassembly the actuator assembly, factory repair or
replacement is recommended.
8.3.10 Bonnet seal omission
After service, during assembly, omission of the bonnet seal will cause the
valve to leak from atmosphere at all times. Remove the actuator assembly
and install the seal.
8.3.11 Nosepiece seal omission
After service, during assembly, omission of the nosepiece seal will cause
the valve to leak from one port to the other when the valve is closed.
Remove the actuator assembly and install the seal.
8.3.12 Improper assembly
After service, the actuator must be inserted to its stop, reference section
7.2.3 on pneumatic actuator assembly installation or 7.3.3 on manual
actuator assembly installation. Failure to do so could result in the valve not
closing completely, or leaking in its closed position.
8.3.13 Loose piston hold down screw –
Pneumatic Actuation Only
The piston hold down screw, a flat head socket drive cap screw, can work
itself loose if not tightened adequately during assembly or if improperly
assembled. Remove the piston cover and,
with the valve closed, remove
the piston hold down screw. Do not remove the accuator assembly from
the body during this process, (If the valve is equipped with the optional
limit switch package, follow the directions for its removal section 7.4.1.)
Apply a light film of a good quality thread locking compound, such as
Tight
11 , to the threads of the piston hold down screw and tighten.
8.3.14 Inadequate lubrication
Pneumatic Actuation
Normally the Square Body LoPro’s dynamic components require very little
lubrication. However, dry environments, high temperatures, and corrosive
atmospheres may exhaust most of the lubricating properties of the greases
used. The least effect of this is to increase the friction on the piston and
stem, but could result to damaged components and failure. Remove the
11) Tight is a trademark of Fel Pro, Inc.