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.
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
This was a source of lead-related health problems in the years before the health hazards of ingesting lead were fully understood; among these were stillbirths and high rates of infant mortality.Lead water pipes were still widely used in the early 20th century, and remain in many households. In addition, lead-tin alloy solder was commonly used to join copper pipes, but modern practice uses tin-antimony alloy solder instead, in order to eliminate lead hazards. Despite the Romans' common use of lead pipes, their aqueducts rarely poisoned people. Unlike other parts of the world where lead pipes cause poisoning, the Roman water had so much calcium in it that a layer of plaque prevented the water contacting the lead itself. What often causes confusion is the large amount of evidence of widespread lead poisoning, particularly amongst those who would have had easy access to piped water.
The pipes were hollowed-out logs, which were tapered at the end with a small hole in which the water would pass through.The multiple pipes were then sealed together with hot animal fat.
They were often used in Montreal and Boston in the 1800s, and built-up wooden tubes were widely used in the USA during the 20th century.
Notification of such a failure of the hydraulic, which may require emergency hydraulic arrival is done by phone, and the arrival of such an emergency can occur within several minutes.
In the phone book you can find phone numbers for such branches emergency hydraulic, which are open around the clock and seven days a week, including holiday periods.But keep in mind that employees emergency hydraulic refuse to come to such repairs, which need not be performed immediately..