# Pressure drop

Pressure drop

Pressure drop is a term used to describe the decrease in pressure from one point in a pipe or tube to another point downstream. "Pressure drop" is the result of frictional forces on the fluid as it flows through the tube. The frictional forces are caused by a resistance to flow. The main determinants of resistance to fluid flow are fluid velocity through the pipe and fluid viscosity. The flow of any liquid or gas will always flow in the direction of least resistance(less pressure). Pressure drop increases proportional to the frictional shear forces within the piping network. A piping network containing a high relative roughness rating as well as many pipe fittings and joints, tube convergence, divergence, turns, surface roughness and other physical properties will affect the pressure drop. High flow velocities and / or high fluid viscosities result in a larger pressure drop across a section of pipe or a valve or elbow. Low velocity will result in lower or no pressure drop. [1]

Pressure Drop can be calculated by 2 values: the Reynolds Number, NRe (determining laminar or turbulent flow), and the relative roughness of the piping, ε/D. NRe = Dvρ/μ Where D is the pipe diameter in metres, v is the velocity of the flow in metres per second, ρ is the density in kilograms per cubic metre, and μ is in kilograms per metre-second. The relative roughness of the piping is usually known and then these two values can be cross referenced using:

http://www.fao.org/docrep/x5744e/x5744eee.gif

By cross referencing the Reynolds number with the relative roughness, the friction factor, f, is calculated. f=(ΔpπR2/2πRΔL)/(ρv2/2) Where solving for Δp will allow for the calculation of pressure drop through a pipe. [2]

[3]

## References

1. ^ The Christmas Tree Farm, http://www.christmas-tree-farm.com/dripterm.html
2. ^ Geankoplis, C. J. (2003). Transport Processes and Separation Process Principles. Upper Saddle River, NJ: Prentice Hall Professional Technical Reference.
3. ^ Welty, James (2008). Fundamentals of Momentum, Heat, and Mass Transfer. United States: Hamilton Printing.

Wikimedia Foundation. 2010.

### Look at other dictionaries:

• Pressure Drop — may refer to:* Pressure Drop (song), by Toots the Maytals, covered by many others * Pressure Drop (album), by Robert Palmer, released in 1975ee also*Pressure drop, in pressure measurement …   Wikipedia

• pressure drop — slėgio krytis statusas T sritis Standartizacija ir metrologija apibrėžtis Staigus slėgio sumažėjimas. atitikmenys: angl. pressure drop vok. Druckabfall, m rus. падение давления, n; спад давления, m pranc. chute de pression, f …   Penkiakalbis aiškinamasis metrologijos terminų žodynas

• pressure drop — slėgio krytis statusas T sritis fizika atitikmenys: angl. pressure drop vok. Druckabfall, m rus. падение давления, n pranc. chute de pression, f …   Fizikos terminų žodynas

• Pressure Drop (song) — Infobox Single Name = Pressure Drop Artist = Toots the Maytals from Album = Monkey Man B side = Smoke Screen (by Beverley All Stars) Released = Start date|1970 Format = 7 single Recorded = 1970 Genre = Reggae Length = Writer = Toots Hibbert Label …   Wikipedia

• Pressure Drop (album) — Infobox Album | Name = Pressure Drop Type = studio Artist = Robert Palmer Released = 1975 Recorded = Genre = Rock Length = 36:54 Label = Island Producer = Steve Smith Reviews = * Allmusic Rating|4.5|5 [http://www.allmusic.com/cg/amg.dll?p=amg sql …   Wikipedia

• pressure drop — [1] The difference in pressure between two points in the system, usually caused by a restriction device. Specifically the difference in pressure where fuel metering occurs. In electronic injection system, this is the difference between fuel… …   Dictionary of automotive terms

• pressure drop — condition in which began a sudden decrease of pressure …   English contemporary dictionary

• Pressure Drop —   The loss in static pressure of a fluid (liquid or gas) in a system due to friction from obstructions in pipes, from valves, fittings, regulators, burners, etc, or by a breech or rupture of the system …   Energy terms

• Frictional pressure drop — The frictional pressure drop is the decrease in pressure as a fluid passes through a conduit, caused by frictional losses within the conduit.This article was created to discuss merging the following articles: *Friction factor *Darcy friction… …   Wikipedia

• admission pressure drop — slėgio mažėjimas įsiurbiant statusas T sritis Energetika apibrėžtis Slėgio mažėjimas vidaus degimo variklio įsiurbimo trakte (oro filtre, karbiuratoriuje, įsiurbimo kolektoriuje, vožtuvuose). atitikmenys: angl. admission pressure drop vok.… …   Aiškinamasis šiluminės ir branduolinės technikos terminų žodynas