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ΔP is the pressure drop across the valve (expressed in psi). In more practical terms, the flow coefficient C v is the volume (in US gallons) of water at 60 °F (16 °C) that will flow per minute through a valve with a pressure drop of 1 psi (6.9 kPa) across the valve.
Large gate valves are sometimes fitted with a bypass controlled by a smaller valve to be able to reduce the pressure before operating the gate valve itself. Gate valves without an extra sealing ring on the gate or the seat are used in applications where minor leaking of the valve is not an issue, such as heating circuits or sewer pipes.
Pressure drop (often abbreviated as "dP" or "ΔP") [1] is defined as the difference in total pressure between two points of a fluid carrying network. A pressure drop occurs when frictional forces, caused by the resistance to flow, act on a fluid as it flows through a conduit (such as a channel, pipe , or tube ).
Used in oil and gas wellheads, where the pressure drop is high. (Not to be confused with engine choke valve, below.) Diaphragm valve or membrane valve, controls flow by movement of a diaphragm. Used in pharmaceutical applications; Gate valve, mainly for on–off control, with low pressure drop; Globe valve, good for regulating flow. Uses a ...
In a nozzle or other constriction, the discharge coefficient (also known as coefficient of discharge or efflux coefficient) is the ratio of the actual discharge to the ideal discharge, [1] i.e., the ratio of the mass flow rate at the discharge end of the nozzle to that of an ideal nozzle which expands an identical working fluid from the same initial conditions to the same exit pressures.
The key quantities are then the pressure drop along the pipe per unit length, Δp / L , and the volumetric flow rate. The flow rate can be converted to a mean flow velocity V by dividing by the wetted area of the flow (which equals the cross-sectional area of the pipe if the pipe is full of fluid).
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[1] [2] [3] A key question is the uniformity of the flow distribution and pressure drop. Fig. 1. Manifold arrangement for flow distribution. Traditionally, most of theoretical models are based on Bernoulli equation after taking the frictional losses into account using a control volume (Fig. 2).