Pneumatic control valves are classified into pneumatic diaphragm control valve and pneumatic piston control valve, which use compressed air as power source. The valves use diaphragm or piston air cylinder as actuator, driven by positioner, convertor, solenoid valve, lock up valve and other accessories to realize switching value or proportional regulation. Pneumatic control valves receive control signals from industrial automation control system to control flow, pressure, temperature and other technological parameters of media inside pipe. Characteristics of pneumatic control valves include simple regulation, rapid reaction and safety without explosion precautions any more. The cost of pneumatic control valves is lower than that of electric control valves. In chemical industry, petrochemical industry and other industries, pneumatic control valves have incomparable advantages, compared with electric control valves.
(1) Pneumatic control valves should be installed on horizontal pipes. In general, pneumatic control valves are supported to ensure steadiness and reliability. In some special situations, control valves also should be support (except for small dimension control valves), when the valves are installed on vertical pipe horizontally. Additional stress which may be brought to control valves must be avoided.
(2) When the dimension of pneumatic control valves is different from pipes, reducing pipe connection should be used. When install small dimension pneumatic control valves, threads connection can be adopted. Arrows of fluid direction marked on body must conform to direction of media.
(3) Working temperature of pneumatic control valves ranges from -30℃ to 60℃. Relative humidity cannot be higher than 95%.
(4) When install positioner for pneumatic control valves, convenience for operation, observation and regulation must be ensured.
(5) Before installation, foreign matters such as dirt and welding slag inside pipes must be cleaned up completely.
May 07,2015
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