29 common types of valves are explained in detail!

29 common types of valves are explained in detail!

The sealing performance of a valve refers to the ability of each sealing part of the valve to prevent medium leakage, which is the most important technical performance index of the valve. There are three sealing parts in the valve: the contact area between the two sealing surfaces of the opening and closing parts and the valve seat; the fitting area between the packing, the valve stem, and the packing chamber; and the connection between the valve body and the valve cover. Among them, leakage from the first part is called internal leakage, commonly known as "inability to close tightly", which will affect the valve's ability to intercept the medium. For shut-off valves, internal leakage is not allowed. Leakage from the latter two parts is called external leakage, that is, the medium leaks from inside the valve to the outside. External leakage can cause material loss, environmental pollution, and even accidents in severe cases. For flammable, explosive, toxic, or radioactive media, external leakage is absolutely not allowed. Therefore, valves must have reliable sealing performance.

Here are detailed explanations of 29 common types of valves:

1. Ball Valve

Structure: The opening/closing component is a spherical disc driven by a stem, rotating 90° around the valve axis to open or close.
Functions: Used for fluid regulation and control, mainly to cut off, distribute, or change the flow direction of media in pipelines.
Features: Excellent sealing performance, easy operation, quick opening/closing, simple structure, compact size, low flow resistance, and lightweight.

2. Gate Valve

Structure: The opening/closing component is a gate plate moving perpendicular to the fluid direction; it can only be fully open or fully closed, not for regulation or throttling.
Functions: Primarily used to cut off media in pipelines, allowing bidirectional flow and easy installation.
Features: Smooth channel, low flow resistance, simple structure, and convenient operation.

3. Butterfly Valve

Structure: The opening/closing component is a disc (butterfly plate) driven by a stem, rotating 90° around its own axis within the valve body to open/close or regulate flow.
Functions: Mainly for cutting off media in pipelines.
Features: Simple structure, flexible operation, quick switching, small size, short structural length, low resistance, and lightweight.

4. Globe Valve

Structure: The opening/closing component is a plug-shaped disc with a flat or conical sealing surface, moving linearly along the valve seat’s central axis to open/close; it cannot be used for regulation or throttling.
Functions: Primarily for cutting off media in pipelines.
Features: Simple structure, easy installation, smooth channel, low flow resistance, and convenient operation.

5. Check Valve

Structure: Automatically opens/closes the disc via the medium’s own flow to prevent backflow; also called non-return valve, one-way valve, or backpressure valve.
Functions: An automatic valve to prevent medium backflow, reverse rotation of pumps/motors, and discharge of container media.
Applications: Critical for preventing reverse flow in pipelines and machinery.

6. Control Valve

Structure: Composed of an actuator and valve body, controlled by signals from a regulatory unit to adjust process parameters (flow, pressure, temperature, liquid level, etc.).
Types: Pneumatic control valves, electric control valves, self-operated control valves.
Applications: Core component in industrial automation for precise process control.

7. Solenoid Valve

Structure: Combines an electromagnetic coil with a direct-flow or multi-port valve, available in normally open/closed types, controlled by AC220V or DC24V power to switch flow direction.
Selection Principles: Prioritize safety, reliability, applicability, and economy.
Applications: Automated control of fluids in industrial systems.

8. Safety Valve

Structure: Normally closed under external force; opens to discharge media when internal pressure exceeds a set value, preventing overpressure in pipelines/equipment.
Applications: Essential safety device for boilers, pressure vessels, and pipelines.
Features: Automatic operation and critical protective function.

9. Needle Valve

Structure: Features a sharp conical valve core, similar to a globe valve but designed for precise flow control and cutting in small-flow, high-pressure gas/liquid systems.
Applications: Critical in instrumentation and measurement pipelines for fine adjustment and shut-off.

10. Trap Valve (Steam Trap)

Structure: Removes condensate, air, and carbon dioxide from steam systems, classified as an energy-saving device.
Functions: Optimizes the efficiency of steam heating equipment; proper selection requires understanding different trap types (e.g., thermostatic, float).

11. Plug Valve

Structure: The opening/closing component is a cylindrical or conical plug that rotates 90° to align or block channels in the valve body.
Applications: Suitable for cutting off, connecting, or diverting media, with rectangular (cylindrical) or trapezoidal (conical) channels.

12. Diaphragm Valve

Structure: Uses a flexible diaphragm (e.g., rubber, PTFE) as the opening/closing component to separate the valve body interior from the bonnet and actuator.
Types: Rubber-lined, PTFE-lined, unlined, and plastic diaphragm valves.
Applications: Ideal for corrosive, sticky, or contaminated media in chemical and pharmaceutical industries.

13. Discharge Valve

Structure: Designed for bottom discharge, sampling, and dead-zone-free shut-off in reactors, storage tanks, and containers, with lifting or lowering operation modes.
Features: Welded to the vessel bottom to eliminate residual media and ensure clean discharge.

14. Exhaust Valve

Structure: Uses a float-and-lever mechanism to vent air accumulated in fluid pipelines (e.g., water supply systems), preventing air pockets that hinder flow.
Working Principle: Activates at system highs to release air as fluid flows.

15. Breathing Valve

Structure: Maintains pressure balance in storage tanks by using weighted positive/negative pressure discs to control exhaust and intake.
Functions: Reduces medium vaporization, prevents overpressure/underpressure, and ensures tank safety.
Applications: Critical for volatile liquid storage (e.g., oil tanks).

16. Filter Valve

Structure: Contains a removable filter cartridge with mesh screens of varying fineness to trap impurities in pipelines.
Functions: Protects downstream equipment by filtering out debris; easy to clean/replace.
Applications: Essential in fluid systems to prevent blockages and equipment damage.

17. Flame Arrester

Structure: Composed of a flame arrestor core, housing, and accessories, designed to block flame propagation in flammable gas/liquid vapor pipelines or vented tanks.
Applications: Critical safety device in petrochemical and gas systems to prevent explosion propagation.

18. Angle Seat Valve

Structure: Actuated by air (with solenoid valves) for rapid, precise control of fluid flow (water, oil, air, steam, etc.).
Features: Quick response, long lifespan, maintenance-free, and suitable for frequent on/off operations.
Applications: Industrial automation for precise flow and temperature control.

19. Balance Valve

Structure: Installed between pipelines/ containers to equalize pressure or flow differences via regulation or flow diversion.
Functions: Specialized valve for pressure/flow balancing in heating, water supply, and HVAC systems.

20. Blowdown Valve

Structure: Derived from gate valves, using a gear-driven stem to rotate 90° for opening/closing.
Features: Simple structure, good sealing, small size, lightweight, low torque, and quick operation.
Applications: Draining sediments and impurities in pipelines/equipment.

21. Sludge Discharge Valve

Structure: Hydraulic/pneumatic actuated angle globe valve, typically installed in rows on sedimentation tank walls.
Functions: Removes sludge and debris from tank bottoms, operable remotely via manual or solenoid valves.

22. Cut-off Valve

Structure: Comprises a multi-spring pneumatic diaphragm actuator or piston actuator with a control valve, driven by regulatory signals.
Functions: Cuts off, connects, or switches fluid flow in automated systems.
Features: Simple design, rapid response, and reliable operation.

23. Reducing Valve

Structure: Adjusts inlet pressure to a desired outlet pressure, maintaining stability via the medium’s own energy.
Working Principle: Acts as a variable orifice to create pressure drops by altering flow area and velocity.
Applications: Pressure regulation in water supply, heating, and industrial pipelines.

24. Pinch Valve

Structure: Consists of cast iron/aluminum/stainless steel bodies, a rubber sleeve, stems, and guide posts; closing compresses the sleeve via stem rotation.
Features: Corrosion-resistant, ideal for abrasive slurries; simple to maintain.
Applications: Mining, wastewater, and chemical industries for thick fluids.

25. Plunger Valve

Structure: Features a plunger driven by a stem within a ported sleeve, with a high-elasticity, wear-resistant sealing ring.
Functions: Opens/closes via plunger reciprocation, offering reliable sealing and long lifespan.
Applications: High-pressure systems requiring tight shut-off (e.g., power plants, chemical plants).

26. Bottom Valve

Structure: Composed of a body, disc, piston rod, bonnet, and positioning posts; pre-fills suction pipes with liquid before pump startup.
Working Principle: Opens during operation to allow flow and closes via liquid pressure/gravity when stopped, preventing backflow.
Applications: Essential for centrifugal pumps in water supply and irrigation systems.

27. Sight Glass

Structure: A transparent viewing device (e.g., glass or quartz) installed in pipelines to monitor fluid flow, color, or reactions.
Applications: Critical in petroleum, chemical, pharmaceutical, and food industries to prevent operational accidents.

28. Flange

Structure: A circular plate with bolt holes for connecting pipes, equipment inlets/outlets, or components.
Functions: Provides a detachable, leak-proof joint for easy maintenance and system expansion.
Types: Welded, threaded, slip-on, and blind flanges, suited for various pressure/temperature conditions.

29. Hydraulic Control Valve

Structure: A main valve paired with pilot lines, needle valves, ball valves, and pressure gauges, operated by pipeline pressure.
Types: Remote float control valves, pressure reducers, slow-closing check valves, flow controllers, pressure relief valves, etc.
Applications: Water supply, irrigation, and industrial systems for automatic pressure/flow control.

This comprehensive list covers the core structures, functions, and applications of common valves, serving as a practical reference for engineering and maintenance.