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Last edited 09 Nov 2021
Valves are mechanical devices that control the flow of fluids such as gas, liquid, fluidised solids, slurries, and so on, by opening, closing or partially obstructing a passage.
- A tap that when turned opens a valve to release pressurised water.
- A toilet that when flushed opens two valves – one that allows water to escape, and another that refills the toilet with more water.
- A gas cooker hob that opens a valve to allow more gas to increase the flame size.
An automated or manual mechanism is used to open and close valves. For high-pressure flow pipework, opening and closing manually can be physically difficult, often requiring a long lever or large wheel. Big valves can be operated using hydraulic rams.
There are several different types of valves, including:
- Ball valve: A hollowed-out ball sits inside a pipe obstructing the flow and swivelling through 90-degrees when turned.
- Butterfly valve: A disc sits inside a pipe and swivels sideways or upright.
- Cock or plug: A cone-shaped plug moves to one side when a wheel or handle is turned.
- Gate or sluice: Metal gates are lowered across pipes, usually only capable of being fully open or fully closed.
- Globe: When turned a valve is screwed in, such as with a tap.
- Needle: A long, sliding needle regulates fluid flow, such as in central heating systems.
- Spool: Valves slide backwards and forwards to direct fluid flow around a pipe circuit, such as in hydraulic systems.
- A guide to installing thermostatic mixing valves: what, why and how.
- BSRIA publishes new edition of BG29.
- BSRIA study: The market for European Field Devices.
- Closed Systems Control Association.
- Differential pressure control valve.
- Flow characteristics.
- Mechanical, electrical and plumbing MEP.
- Pipework defects, ventilation and airflow rates.
- Pressure independent control valves.
- Pressure-relief valve.
- Pumps and dewatering equipment.
- Thermostatic mixing valve.
- Types of valve.
- Water hammer.
- What makes a good PICV?
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