Valves

Valves are components in a piping system provided to regulate or stop the liquid
Flow.

Various types exist with their associated particular function or
Advantages.

TYPES OF VALVES

Example of the commonly used valves in piping systems include;

• Gate valve
• Globe Valve
• Check valve
• Plug valve
• Ball valves
• Pressure Relief valve
• Needle valve
• Pinch valve and
• Butterfly valves.

CLASSIFICATION OF VALVES

• FUNCTION: Valves can be classified by their usage and functionality in a piping system. Below are functions of valve and example of valves that fall under each category.NOTE: Some valves may fall under more than one function, each example given under each category is in order of preference and most suitable.

1. ISOLATION: Isolation valves function mainly to restrict or stop liquid flow in a piping system. Examples (in order of most suitable) include; Gate valves, plug valves, piston valves, diaphragm valves, butterfly valves and pinch valves.
2. REGULATION: Regulating valves are used to regulate liquid flow across a line or piping system. Examples (in order of most suitable) include; globe valves, needle valves, butterfly valves, diaphragm valves, ball valves, plug valves and pinch valves.
3. NON-RETURN: Non return valves are used to prevent back flow or residing of liquid flow in a piping system. They are used to ensure one directional flow of liquid across a line. Examples (in order of most suitable) include; swing check valves, lift check valves.
4. SPECIAL PURPOSE: Special purpose valves includes; multiport valves, float valves, foot valves, knife gate valves.
5. SAFETY RELIEF VALVE: Safety Relief valves are used in a piping system to prevent high pressure buildup in a pipe during liquid flow. It serves as a safety mechanism which prevents a pipe from bursting as a result of excessive pressure buildup. Examples ( in order of most suitable) include; Pressure relief valves, vacuum relief valves.

• MODE OF OPERATION: Each valve have a peculiar mode of operation which determines the point of its installation in a piping system.

1. LINEAR: valves operating linearly includes Gate valves, globe valves, lift check valves, inline check valves, stop check valves, pinch valves, diaphragm valves, and safety relief valves. Linearly operated valves either open from side to side or top to bottom and vice versa.
2. ROTARY: Swing check valves, Folding disc check valves, Stop check valves, Ball Valves, Butterfly valves and Plug valves. These valves open at angles such as 90-180 degrees.
3. QUARTER TURN: Ball valve, Butterfly valve and Plug valve may turn quarterly.

• TYPE OF ACTUATOR: A valve actuator is a component of a valve responsible for moving and control mechanism of the valve.

1. MANUAL: Hand wheel, Hand lever, Gear wheel and Chain are actuators operated manually.
2. POWER: Electric or Motor actuation, Air or Pneumatic actuation, Hydraulic actuation, Solenoid actuation.
3. AUTOMATICALLY ACTUATED VALVES.

• METHOD OF CONNECTIONS: All valves have connections both at the inlet side and outlet side.

1. Flange connection end
2. Socket welded end
3. Threaded/screwed end