Plastic pipework is used for the conveyance of drinking water, waste water, chemicals, heating fluid and cooling fluids, foodstuffs, ultra-pure liquids, slurries, gases, compressed air and vacuum system applications. Plastic pipe systems fulfil a wide variety of service requirements.
These requirements are precisely described in a complete set of European Product Standards for each application alongside their specific characteristics. For example: Conveyance of drinking water: Hygienic requirements Conveyance of gas: Highest Safety requirements Plastic pipes for radiant heating and floor heating: Temperature resistance over decades Sewer applications: High chemical resistance. Plastic pipes are perfectly capable of fulfilling the specific requirement for each application.
A valve is a device that regulates, directs or controls the flow of a fluid (gases, liquids, fluidized solids, or slurries) by opening, closing, or partially obstructing various passageways.
In an open valve, fluid flows in a direction from higher pressure to lower pressure.The word is derived from the Latin valva, the moving part of a door, in turn from volvere, to turn, roll. 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.
Modern control valves may regulate pressure or flow downstream and operate on sophisticated automation systems. Źródło: https://en.wikipedia.org/wiki/Valve.