hydraulika: Valve

Evidence: 100 • authority: 72

A valve is a device or natural object 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, which describes the moving part of a door, in turn from volvere, which means to turn or roll. The simplest, and very ancient, valve is simply a freely hinged flap which swings down to obstruct fluid (gas or liquid) flow in one direction, but is pushed up by the flow itself when t…

Evidence: 63 • authority: 72

A pressure regulator is a valve that controls the pressure of a fluid to a desired value, using negative feedback from the controlled pressure. Regulators are used for gases and liquids, and can be an integral device with a pressure setting, a restrictor and a sensor all in the one body, or consist of a separate pressure sensor, controller and flow valve. Two types are found: the pressure reduction regulator and the back-pressure regulator. A pressure reducing regulator is a control valve that reduces the input pressure of a fluid to a desired value at its output. It is a normally-open valve and is installed upstream of pressure-sensitive equipment. A back-pressure regulator, back-pressure…

Evidence: 52 • authority: 72

A blowout preventer (BOP) (pronounced B-O-P) is a specialized valve or similar mechanical device, used to seal, control and monitor oil and gas wells to prevent blowouts, the uncontrolled release of crude oil or natural gas from a well. They are usually installed in stacks of other valves. The earliest blowout preventers; Regan Type K Annulars were used, beginning in the 1930s to cope with extreme erratic pressures and uncontrolled flow (formation kick) emanating from a well reservoir during drilling. Kicks can lead to a potentially catastrophic event known as a blowout. In addition to controlling the downhole (occurring in the drilled hole) pressure and the flow of oil and gas, blowout pre…

Evidence: 51 • authority: 72

The flow coefficient of a device is a relative measure of its efficiency at allowing fluid flow. It describes the relationship between the pressure drop across an orifice valve or other assembly and the corresponding flow rate. A greater restriction in flow will create a larger pressure drop across a device and thus a smaller flow coefficient, conversely device with little restriction in flow will have a small pressure drop and a larger flow coefficient. For example, the flow coefficient of a 1" ball valve may be 80 while a similarly sized globe valve in the same application may be 10. Mathematically the flow coefficient Cv (or flow-capacity rating of valve) can be expressed as C v = Q RD Δ…