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Backflow is a term in plumbing for an unwanted flow of water in the reverse direction. [1] It can be a serious health risk for the contamination of potable water supplies with foul water . In the most obvious case, a toilet flush cistern and its water supply must be isolated from the toilet bowl.
In many countries or regions they are mandatory to be installed at the gas regulator or gas outlet/ tapping point. Depending on the application they are also often used at the torch side as an additional safety device. Flashback arrestors help prevent: Further gas flow in the case of pressure shocks.
A swing check valve (or tilting disc check valve) is a check valve in which the disc, the movable part to block the flow, swings on a hinge or trunnion, either onto the seat to block reverse flow or off the seat to allow forward flow. The seat opening cross-section may be perpendicular to the centerline between the two ports or at an angle.
Non-return or check valves allow the free flow of a fluid in one direction but prevent its flow in a reverse direction. They are often seen in drainage or sewage systems but may also be used in pressurized systems. Valves are available in several types, based on design and purpose: Gate, plug, or ball valves – Isolation; Globe valve ...
The fluid exerts a constant pressure on the surface once it has separated instead of a continually increasing pressure if still attached. [4] In aerodynamics, flow separation results in reduced lift and increased pressure drag, caused by the pressure differential between the front and rear surfaces of the object. It causes buffeting of aircraft ...
Back pressure is the term used for the hydraulic pressure required to create a flow through a chromatography column in high-performance liquid chromatography, the term deriving from the fact that it is generated by the resistance of the column, and exerts its influence backwards on the pump that must supply the flow. Back-pressure is a useful ...
[4] [5] [6] A generalized model of the flow distribution in channel networks of planar fuel cells. [6] Similar to Ohm's law, the pressure drop is assumed to be proportional to the flow rates. The relationship of pressure drop, flow rate and flow resistance is described as Q 2 = ∆P/R. f = 64/Re for laminar flow where Re is the Reynolds number.
The flow resistance is defined, analogously to Ohm's law for electrical resistance, [2] as the ratio of applied pressure drop and resulting flow rate: R = Δ p Q {\displaystyle R={\frac {\Delta p}{Q}}} where Δ p {\displaystyle \Delta p} is the applied pressure difference between two ends of the conduit, and Q {\displaystyle Q} the flow rate.