Pipes - Fluid Flow Velocities
Imperial units
Fluid flow velocity in a circular pipe can be calculated with Imperial or American units as
v = 1.273 q / d 2
= 0.4084 q gpm / d in 2 (1)
where
v = velocity (ft/min, ft/s)
q = volume flow (ft 3 /s, ft 3 /min )
d = pipe inside diameter (ft)
q gpm = volume flow (US gal/min, gpm)
d in = pipe inside diameter (inches)
Online Pipe Velocity Calculator - Imperial Units
Dimensions: Steel Pipes schedule 40 & 80 , PVC and CPVC Pipes Schedule 40 & 80 , Copper Tubes and PEX Tubes
SI units
Fluid flow velocity in a circular pipe can be calculated with SI units as
v = 1.273 q / d 2 (2)
where
v = velocity (m/s)
q = volume flow (m 3 /s)
d = pipe inside diameter (m)
Online Pipe Velocity Calculator - SI Units
Example - Flow Velocity in a Steel Pipe
60 US gal/min is flowing through a 4 inch schedule 80 steel pipe . The internal diameter of the pipe is 3.83 in . The velocity can be calculated as
v = 0.4085 ( 60 gal/min ) / (3.83 in) 2
= 1.7 ft/s
Related Topics
• Fluid Flow and Pressure Loss
Pipe lines - fluid flow and pressure loss - water, sewer, steel pipes, pvc pipes, copper tubes and more.
• Fluid Mechanics
The study of fluids - liquids and gases. Involving velocity, pressure, density and temperature as functions of space and time.
• Pipe Sizing
Sizing of steam and condensate pipe lines - pressure loss, recommended velocity, capacity and more.
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