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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 ).
In engineering, the Moody chart or Moody diagram (also Stanton diagram) is a graph in non-dimensional form that relates the Darcy–Weisbach friction factor f D, Reynolds number Re, and surface roughness for fully developed flow in a circular pipe. It can be used to predict pressure drop or flow rate down such a pipe.
Friction loss is then the change in pressure Δp per unit length of pipe L Δ p L . {\displaystyle {\frac {\Delta p}{L}}.} When the pressure is expressed in terms of the equivalent height of a column of that fluid, as is common with water, the friction loss is expressed as S , the "head loss" per length of pipe, a dimensionless quantity also ...
In the English service electric tubes (in the United States called "primers") are mostly used, but percussion or friction tubes are preferred on the continent and electric tubes are seldom or never used. [3] There are two types of electric tube, one with long wires for joining up with the electric circuit and the other without external wires.
Fanning friction factor for tube flow. This friction factor is one-fourth of the Darcy friction factor, so attention must be paid to note which one of these is meant in the "friction factor" chart or equation consulted. Of the two, the Fanning friction factor is the more commonly used by chemical engineers and those following the British ...
Example Number 2: A well or bore with an operating level of 5 metres below the intake, minus a 2 metre friction loss into pump (pipe loss), minus the NPSH R curve (say 2.4 metres) of the pre-designed pump = an NPSH A (available) of (negative) -9.4 metres. Adding the atmospheric pressure of 10 metres gives a positive NPSH A of 0.6 metres.
The equation was derived by Kozeny (1927) [1] and Carman (1937, 1956) [2] [3] [4] from a starting point of (a) modelling fluid flow in a packed bed as laminar fluid flow in a collection of curving passages/tubes crossing the packed bed and (b) Poiseuille's law describing laminar fluid flow in straight, circular section pipes.
The resulting term is one that can be easily calculated from the results of two simple measurements: a pressure survey by the gauge and tube method and a flowrate survey with a counting anemometer. This is a major strength and is the reason why Atkinson resistance remains in use today.