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. Valves are technically fittings, but are usually discussed as a separate category. 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/ValveWhere water resources or infrastructure or sanitation systems are insufficient for the population, people fall prey to disease, dehydration, and in extreme cases, death. Major human settlements could initially develop only where fresh surface water was plentiful, such as near major rivers.
About water supply and sanitationWater supply and sanitation has been a primary logistical challenge since the dawn of civilization.
Over the millennia, technology has dramatically increased the distances across which water can be relocated, but the availability of clean and fresh water remains a limiting factor on the size and density of population centers, and is expected to remain so into the foreseeable future.Źródło: https://en.wikipedia.org/wiki/History_of_water_supply_and_sanitation
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..
Product standards for plastics pipe systems are prepared within the standards committee known as CEN/TC155.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.They do so with a high level of performance over a long lifetime and with reliability and safety. The key factor for success is achieved by maintaining consistently high quality levels.For plastic pipe products, these levels are closely defined by the different standards.Źródło: https://en.wikipedia.org/wiki/Plastic_pipework