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

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Square Body LoPro Square Body LoPro
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8.3.4 Particulates, condensation, and corrosion
In normal use, airborne particulates, process condensation, and/or
corrosion, may effect seal integrity. Particulates might be moved by simple
turbulent gas flow. However, condensed or sublimated films nearly always
require further cleaning. Additionally, corroded sealing surfaces may be
irreparable. Replacing the component being the only remedy.
8.3.5 Bellows failure
Although the mean time between failures for the Square Body LoPro
bellows is greater than 10
6 cycles, nearly all valve failures are the result of
bellows failures. Stress cracks in the convolution crowns are first detected
when the valve is open and the bellows is in compression. At this time, the
outside of the bellows material is in tension, opening minute cracks wider
than when the bellows is relaxed or in extended. Eventually, the crack(s)
will propagate around the entire convolution and the bellows will separate.
Long before, the atmospheric leak will be detected constantly. The only
remedy is to replace the actuator assembly.
8.3.6 Nosepiece seal failure
Elastomer seals that have remained in a compressed condition for long
periods of time may not return to their original circular cross section
when released. Such seals may stick to the mating sealing surface as
they are pulled apart, leaving bits of the seal behind. Old elastomers
tend to lose some of their elasticity and may crack. Various process
gasses and/or high temperatures accelerate all of these effects.
Reference section 7.2.2 on o-ring replacement.
8.3.7 Bonnet seal failure
Elastomer seals that have remained in a compressed condition for long
periods of time may not return to their original circular cross section when
released. Such seals may stick to the mating sealing surface as they are
pulled apart, leaving bits of the seal behind. Old elastomers tend to lose
some of their elasticity and may crack. Various process gasses and/or high
temperatures accelerate all of these effects. Reference section 7.2.2 on
o-ring replacement.
8.3.8 Piston seal failure – Pneumatic Actuation Only
The seals used on the pneumatic pistons 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.