Valves are classified based on various factors, including their design, operation, function, and application. Here are some common classifications of valves:

1. Based on Design:

   • Gate Valve: Features a gate or wedge that rises and falls to control flow.
   • Globe Valve: Has a plug or disc that moves perpendicular to the flow to regulate flow rate.
   • Ball Valve: Uses a rotating ball with a bore to control flow.
   • Butterfly Valve: Utilizes a disc mounted on a rotating shaft to control flow.
   • Check Valve: Allows flow in one direction only, preventing backflow.
   • Plug Valve: Uses a cylindrical or tapered plug to control flow through rotation.
   • Diaphragm Valve: Employs a flexible diaphragm to control flow.
   • Pinch Valve: Utilizes a pinching mechanism to regulate flow by compressing a flexible tube or sleeve.
   • Needle Valve: Features a long, tapered needle-like stem to control precise flow rates.

2. Based on Operation:

   • Manual Valve: Operated by hand using a lever, wheel, or handle.
   • Automatic Valve: Actuated automatically in response to changes in pressure, temperature, or flow.
   • Solenoid Valve: Actuated by an electric solenoid, which controls the valve position.
   • Pneumatic Valve: Actuated by air pressure, commonly used in pneumatic systems.
   • Hydraulic Valve: Actuated by hydraulic pressure, commonly used in hydraulic systems.
   • Motorized Valve: Actuated by an electric motor, providing precise control and automation.

3. Based on Function:

   • Isolation Valve: Used to isolate or shut off flow in a pipeline.
   • Regulating Valve: Used to control or regulate flow rate or pressure within a system.
   • Relief Valve: Designed to open and relieve excess pressure to protect equipment from overpressure conditions.
   • Safety Valve: Similar to a relief valve but typically set to open at a predetermined pressure to prevent overpressure situations.
   • Control Valve: Used to regulate fluid flow, pressure, temperature, or level in a process control system.
   • Throttle Valve: Used to control the rate of flow by partially obstructing the flow path.
   • Mixing Valve: Combines multiple fluid streams to achieve a desired blend or temperature.
   • Diverting Valve: Directs flow from one path to another, typically used in branching pipelines.

4. Based on Application:

   • Water Valve: Designed specifically for water applications, such as in plumbing systems.
   • Gas Valve: Designed for use with gas media, often in heating, ventilation, and air conditioning (HVAC) systems.
   • Oil Valve: Suitable for use with oil-based fluids, commonly found in industrial processes and machinery.
   • Steam Valve: Designed to handle high-temperature steam, often used in steam systems and boilers.
   • Cryogenic Valve: Designed to handle extremely low temperatures, commonly used in cryogenic storage and transportation applications.

These are some of the common classifications of valves, and each type has specific characteristics and advantages suited to different applications and industries.