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.
What and elbow pipe is?
An elbow is a pipe fitting installed between two lengths of pipe or tubing to allow a change of direction, usually a 90° or 45° angle, though 22.5° elbows are also made. The ends may be machined for butt welding, threaded (usually female), or socketed, etc. When the two ends differ in size, the fitting is called a reducing elbow or reducer elbow.
Elbows are categorized based on various design features as below:
Long Radius (LR) Elbows ? radius is 1.5 times the pipe diameter
Short Radius (SR) Elbows ? radius is 1.0 times the pipe diameter
90 Degree Elbow ? where change in direction required is 90°
60 Degree Elbow ? where change in direction required is 60°
45 Degree Elbow ? where change in direction required is 45°
A 90 degree elbow is also called a "90 bend" or "90 ell". It is a fitting which is bent in such a way to produce 90 degree change in the direction of flow in the pipe. It is used to change the direction in piping and is also sometimes called a "quarter bend". A 90 degree elbow attaches readily to plastic, copper, cast iron, steel and lead. It can also attach to rubber with stainless steel clamps. It is available in many materials like silicone, rubber compounds, galvanized steel, etc. The main application of an elbow (90 degree) is to connect hoses to valves, water pressure pumps, and deck drains. These elbows can be made from tough nylon material or NPT thread.
Conducting self-activity of the hydraulic
Persons employed as plumbers can sign various contracts of employment. They work full-time in a variety of plants, hydraulic or sign contracts-orders for certain services. Some plumbers also run his own business, under which perform minor plumbing services. Nowadays, self-employed persons often assume hydraulic websites, which include information on the services rendered by them and their price list. They also by posting information about their activities on bulletin boards, and even spread leaflets around the city to encourage use of their services. So they can get regular customers, who will often benefit from their services.