Praesto Engineering Company (PEC) is an Engineering Design and Consultancy company based in Perth, Australia. PEC was formed to provide engineering services and products to the Oil/gas, Mining, Process and Manufacturing industries. PEC's core competencies include pressure vessel design, heat exchanger design, valve design, Solidworks design, engineering consultancy and FEA. PEC also offers "bolts and fasteners" and Pipe flanges to the industry.
A Valve is a mechanical device which is used to isolate, regulate or direct the flow of fluids through pipelines. Its function can be stopping or starting the flow, controlling flow rate, diverting flow, preventing back flow, controlling pressure, or relieving pressure. There are different types of valve constructions. It is very important to select the correct valve to fulfill these functions.
Basically, the valve is an assembly of components which are connected to the piping and some sealing elements. Valves are found in virtually every industry, including Water Processing, Mining, Power Generation, Oil & Gas, Food Industries, Chemical Industries and many more.
Type of valves
The valves can be classified into different categories as mentioned below.
1. Based on Functionality of the valve
I. Isolation valves, On/off valves. These valves are used for either stopping or starting the flow of fluid and typically operated as fully open or fully closed. Ball valve, Plug valve, Butterfly valve, Gate valve can be used in this category.
II. Control valves. These valves are used to vary the flow of fluid by opening or closing by a certain percentage as per the requirement of the process. Ball valve, Plug valve, Butterfly valve, Gate valve can be used as control valves when they are accompanied by positioner and actuator.
III. Check Valves. These valves are used to allow the flow of fluid only in one direction. It prevents the flow of fluid from the other direction. Hence they are also known as non-return or one-way valves.
IV. Relief/Safety valve. These valves are used to limit the pressure in a system or vessel to a predetermined maximum set pressure. The system pressure may increase beyond the set pressure as a result of any abnormal condition like process upset or fire. These valves will prevent the pressure from rising above this set pressure and safeguards the system or vessel from overpressure.
2. Based on Number of openings in the closure member
I. Two Port Valves. These are the most common type among the valves. Operating position of these valves can be open, closed or partially open.
II. Three port valves. These valves are used to divert the flow of fluid to the different direction.
III. Four port valves. These valves are used for simultaneous operation e.g. isolating one port and bypassing the other port.
3. Based on Operation/Actuation
I. Manually operated valve. These are the valves operated manually using levers or gear operators. No extra source of energy is used to operate these valves. These valves are generally used if they will be operated infrequently.
II. Actuated valve. These are the valves operated by some external means typically known as Actuators. Actuators may be pneumatic, hydraulic, electric or combination of these power sources.
III. Self-actuated valve. These are the valves operated automatically by the process itself. Check valves and Pressure relief valves are self-actuated valves.
IV. Solenoid operated Valve. These are the valves operated by electromechanical solenoids. They are widely used in hydraulic and pneumatic industries.
4. Based on motion of the closure member
I. Multi turn valve (Liner Motion Valves). The closure member is displaced in a linear direction by turning its threaded stem several times. This operation is generally slow, but it gives accuracy and stability to the position of the closure member. Gate valve, Globe valve, Needle valve are these types of valves.
II. Rotary - Quarter turn valves. The closure member turns from 00 to 900 from fully open to closed position. Ball Valve, Butterfly valve, Plug valve are these types of valves.
The author of this article is a professional writer who writes on industry related topics. He has couple years of experience writing on pressure vessel design, bolts and fasteners, Mechanical drafting, engineering consultants and many more. His articles guide the reader in proper way.
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