plumber Hammersmith Plumbing - what a valve is?
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/Valve
Plumbing performed in the course of putting the apartment block
Large companies engaged in hydraulic performance of full-service plumbing. They can be rented during the construction of the house. They also participate in the process of putting up apartment buildings and schools of all sizes. It seems that the least complicated plumbing services are performed in the course of construction of the house, because they are limited to the performance of domestic water supply and sewage, and in the case of apartment blocks need to make a detailed plan of such a network adequate to the number and position of the individual apartments. However, in the case of schools you need to equip the bathroom in the right amount of sinks, where you will be able to wash their hands after using the toilet. In schools, sports can also stand up showers.
Plumbing - about materials
Water systems of ancient times relied on gravity for the supply of water, using pipes or channels usually made of clay, lead, bamboo, wood, or stone. Hollowed wooden logs wrapped in steel banding were used for plumbing pipes, particularly water mains. Logs were used for water distribution in England close to 500 years ago. US cities began using hollowed logs in the late 1700s through the 1800s.8 Today, most plumbing supply pipe is made out of steel, copper, and plastic; most waste (also known as "soil")11 out of steel, copper, plastic, and cast iron.11
The straight sections of plumbing systems are called "pipes" or "tubes". A pipe is typically formed via casting or welding, whereas a tube is made through extrusion. Pipe normally has thicker walls and may be threaded or welded, while tubing is thinner-walled and requires special joining techniques such as brazing, compression fitting, crimping, or for plastics, solvent welding. These joining techniques are discussed in more detail in the piping and plumbing fittings article.
Źródło: https://en.wikipedia.org/wiki/Plumbing#Materials