The Importance Of Control Valves-shdoclc.dll

Business There are thousands and thousands of control valves in process plants which are combined together to manufacture a finished product for sale. These control loops are designed in such a manner that they keep some process variable like flow, temperature, level etc. It is kept within a desired operating range in order to ensure the best quality of the product. The control loops receive and create internal problems that may hamper the process variable and thereby its communication from other loops in the network. Most of the process control industries rely on the common final control element that is control valve. Control valves are normally used to control different conditions such as pressure, liquid, temperature and flow level. Control valves helps to keep the regulated process variable at a desired set point. Usually, control valves are referred as control valve assembly that typically comprises of the internal trim parts, the valve body and an actuator that provides the motive power to run the control valve. Apart from that, it also consists of a huge variety add on valve accessories such as supply pressure regulators, manual operators, snubbers, transducers and positionrs. There can be different types of control valves. The most versatile and common types are angle valves and sliding-term globe. These are suitable for a wide variety of process applications. There are three common methods with which one can install the control valves in the pipelines such as screwed pipe threads, welded end connections and bolted gasket flanges. Control valve bodies can be classified as follows: 1)Globe valves: It can be three-way valve bodies, double-ported valve bodies, port-guided single-port valve bodies, single-port valve bodies and balanced-plug cage-guided valve bodies. 2)Angle valves: Disk Stack style valve bodies and cage-style valve bodies. 3)Rotary valves: V-notch ball control valve bodies, eccentric-plug or eccentric-disk control valve bodies and butterfly valve bodies. 4)Sliding cylinder valves: Spool valve, directional control valve and piston valve. 5)Air operated valves: Relay valve, air operated pinch valve and relay valve. 6)Angle seat piston valves 7)Diaphragm valves Directional control valves are very important parts in hydraulic machinery. They usually have a piston inside a cylinder to ensure that the fluid flow into different directions from different sources. The fluid flow is managed by the movement of the cylinder. It can restrict or permit the actual flow of the fluid. The piston is normally controlled either electrically or mechanically. There are two types of directional control valves- hydraulic and pneumatic. Whereas hydraulic directional control valves are meant for a liquid working fluid, pneumatic directional control valves are for a gaseous working fluid. Liquid working fluid can be hydraulic oil or water and gaseous working fluid is usually air. The most common features of control valves include chemical resistance, self-lubricating, wear resistance and chemical resistance. Apart from that, the quality of a good control valve is that the temperature and pressure level ranges from 60 degree F to + 400 degree F. About the Author: 相关的主题文章: