Valve selection is the process of choosing the appropriate valve for a specific application based on various factors such as the type of fluid or gas being handled, the operating conditions, and the required performance characteristics.
Valves are mechanical devices used to regulate the flow of fluids or gases in a piping system, and proper valve selection is crucial to ensure the safe and efficient operation of the system. The selection of a valve should take into consideration several factors, including the flow rate, pressure, temperature, and chemical compatibility of the fluid or gas being handled, as well as the required level of control or regulation.
The type of valve selected can also affect the performance of the system, as different valves have different characteristics, such as flow capacity, pressure drop, and shut-off capability. Common valve types include ball valves, globe valves, gate valves, butterfly valves, and check valves, each with its unique features and benefits.
In addition to considering the fluid or gas properties and operating conditions, valve selection may also involve evaluating factors such as cost, reliability, ease of maintenance, and compatibility with other system components. Working with a qualified valve supplier or engineer can help ensure that the appropriate valve is selected for the specific application and that it meets all necessary safety and performance standards.
Valves are important mechanical (sometimes electro-mechanical) devices that help in controlling the fluid flow through pipes or tubes. Selecting the right kind of economic valve for a specified fluid service requires many considerations. This article provides guidelines for the selection of normal-type valves. (Special-type valves are not covered in this article).
It should be recognized that Valve Selection is a very extensive and complex subject and it is not possible to select only one type based on this article. The valve selected to work under the same conditions will differ from one client to another. It is necessary to compare the cost and come to an agreement with the client.
Selection Principles:
1. Safety and Reliability: Industries such as petrochemicals, power plants, and metallurgy demand continuous, stable, and long-term operation. Therefore, it is crucial to choose valves with high reliability and a significant factor of safety to ensure the device's long-term operational requirements are met.
2. Process Compatibility: Valves should meet the specific requirements of the medium used, working pressure, working temperature, and intended purpose. This is a fundamental criterion for valve selection.
3. User-Friendly Operation, Installation, Maintenance, and Upkeep: Valves should be installed in a manner that enables operators to easily identify the valve's direction, opening indicators, and indication signals. This facilitates prompt and decisive handling of any emergency faults that may arise.
4. Economy: While meeting the operational demands of process pipelines, preference should be given to valves with relatively low manufacturing costs and simple structures. This approach helps reduce device costs, minimize valve raw material waste, and lower the overall expenses associated with valve installation and maintenance in the long run.
Selection Steps:
1. Identify Valve Working Conditions: Determine the valve's working conditions based on its purpose within the device or process pipeline. Consider factors such as the working medium, working pressure, and working temperature.
2. Determine Sealing Performance Level: Based on the working medium, working environment, and user requirements, select the appropriate sealing performance level for the valve.
3. Choose Valve Type and Driving Method: Consider the purpose of the valve and select the appropriate type, such as block valves, regulating valves, safety valves, or other special-purpose valves. Also, determine the driving method, such as worm gear, worm, electric, pneumatic, etc.
4. Match Nominal Parameters: Ensure that the nominal pressure and size of the valve are compatible with the installed process pipeline.
5. Decide Connection Form: Based on the actual operating conditions and the valve's nominal size, choose the suitable connection form between the valve end face and the pipeline. Options include flanges, welding, clamps, or threads.
6. Consider Structural Form: Take into account the installation position, space constraints, and nominal size to determine the appropriate structural form of the valve type. Examples include non-rising stem gate valves, angle globe valves, fixed ball valves, etc.
7. Select Correct Materials: Based on the medium's characteristics, working pressure, and working temperature, choose the appropriate materials for the valve casing and internal components in a correct and reasonable manner.
