Description

The simplest, and very ancient, valve is simply a freely hinged flap which drops to obstruct fluid (gas or liquid) flow in one direction, but is pushed open by flow in the opposite direction. This is called a check valve, as it prevents or "checks" the flow in one direction.

• A valve is a device that regulates, directs or controls the flow of a fluid (gases, liquids, fluidized solids, orslurries) by opening, closing, or partially obstructing various passageways.

• Valves are technically valvesfittings, but are usually discussed as a separate category.