By the used power of the executive agencies, control valves can be divided
into pneumatic, electric, hydraulic, manual and self-regulating, those are
pneumatic control valve used the compressed air as power source, the electric
control valve used electric for power source, hydraulic control valve used the
pressure of liquid medium (such as oil) for power source, manual control valve
operated by hand, self-regulating valve relied on pressure and temperature of
medium flowing through the valve as an energy-driven. Besides, according to its
functions and features, there are also solenoid valves, electronic, intelligent,
field bus-based control valve etc.
Control Valve has the characteristics of simple structures and reliable
action. Because of its direct contact with technology media, its performance
directly affects system quality and environmental pollution, so the control
valve must be regularly maintained and periodic mend, especially for the hard
useful conditions and important occasions, maintenance work should be paid more
attentions. Focus on the following examination parts:
1. Body wall. For the control valve used in high-pressure differential and
corrosive media occasions, body wall and diaphragm of diaphragm valve are often
subject to impact and corrosion of medium, so examination of pressure, corrosion
must be focused on.
2. Control Valve seat. When the control value is working, due to media
penetration, threaded inner surface of the fixed value seat is so susceptible
corroded that leaving the seat loose, which should be noted in inspection. For
the valve working on the pressure differential, it also should be checked
whether sealing surfaces of control valve seat should be washed out.
3. The spool valves. They are moving parts of regulating the work, and are
eroded and corroded most severely by the media, it should be carefully checked
whether all parts of spool valves are corroded or wore, especially in the case
of high-pressure wear and tear of the spool value are more severer, which should
be noted. The spool valve should be replaced when seriously damaged, in addition
it should also be paid attention whether there is a similar phenomenon on value
stem, or a loose connection with the valve and so on.
4. The diaphragm such as
2012-05-08
