Valves play a vital role in industrial fluid control systems. Different types of valves are suitable for different application scenarios due to their unique design and function. The following is a detailed introduction to several common valve types and their application scenarios, designed to help readers better understand and select valves.
Gate Valves
Gate valves are suitable for on/off operations in most temperature ranges, as well as for non-vibrating hydrocarbons and utilities. However, in vibrating environments, gate valves may open or close unexpectedly from their normal position. The torque characteristics of gate valves are superior to those of ball and plug valves, but operation is not as convenient as a 90-degree rotary action.
RECOMMENDED APPLICATIONS: For manual gate valves sized DN50 (2 inches) or larger, resilient or expansion gates are recommended. Note that chevron gate valves usually do not have cavity overpressure protection.
Not Recommended Application: Unprotected open stem gate valves are not suitable for use in marine environments because the exposed stem and threads are susceptible to corrosion, resulting in difficult operation and damage to the stem packing.
Ball Valves
Ball valves perform well in temperatures from -29°C to 200°C and are suitable for hydrocarbon and utility systems. Metal-sealed ball valves should be considered for high-temperature or abrasive operations, but operating torque will increase.
Design types: float and trunnion. Float type may produce high operating torque at high pressures or large pipe diameters, but seal better.
Not Recommended Applications: Ball valves are not suitable for throttling because partial opening can damage sealing surfaces.
Globe Valves
Globe valves are the best choice when good throttling control is required (e.g., control valve bypass lines or small air vents).
Check Valves
Check valves are available in a variety of forms, including swing-opening, lift-opening, ball-opening, piston-opening, and separating disc swing-opening.
Swing-opening check valves: suitable for most non-fluctuating situations, also suitable for vertical pipelines (flow direction upwards), but not for vertical pipelines where the flow direction is downwards.
Thin design: space-saving, suitable for installation between two flanges, but need to be disassembled for repair.
Double-disc thin check valve: small size, light weight, commonly used in offshore oil, but not applicable to pulsating operations.
Lift check valve: only suitable for small diameter, high pressure pipeline on the clean fluid.
Spherical check valve: suitable for frequent changes in the direction of flow of clean fluids.
Self-balancing piston check valves: recommended for pipelines with fluctuating flow rates, such as the outlet pipelines of reciprocating compressors and pumps, but not for fluids containing sand or impurities.
Butterfly Valve
Ordinary butterfly valves are suitable for rough throttling and low-pressure, non-hydrocarbon, non-hazardous operations. For high temperature or hazardous fluid operations, non-linear butterfly valves should be used.
Diaphragm Valves
Diaphragm valves consist of a diaphragm made of synthetic rubber connected to the valve stem, and closure is achieved by pressing the diaphragm against a metal tab. Mainly used for low-pressure water operations, they are particularly suitable for systems containing sand and other solid particles.
Plug Valves
Plug valves are suitable for hydrocarbon and utility system operations. Plug valves with 90 degree rotary operation are available in lubricated and non-lubricated designs. Lubricated models require regular oil lubrication to maintain good sealing and ease of operation; non-lubricated models use soft materials such as Teflon and nylon for sealing and do not require frequent maintenance lubrication.
Needle Valves
Needle valves are small shut-off valves commonly used as shut-off valves for instruments and pressure gauges, as well as for small flow throttling and pressure fluctuation reduction. Note that needle valves have very small passages and are prone to clogging.
By understanding the characteristics and applicable scenarios of different types of valves, you can choose the right type of valve for your specific needs to ensure the safe, stable and efficient operation of industrial fluid control systems.