Flow Rate of Fluid in Pipe

The Flow Rate of Fluid in Pipe calculator computes the volumetric flow-rate based on the   Pipe Flow interior radius of circular conduit (r), the pressure (P), fluid viscosity (η) and the length (L) of the pipe.

INSTRUCTIONS: Choose units and enter the following:

• (r)  The inner radius of the pipe or conduit.
• (P) The change in pressure
• (η) The fluid viscosity (0.001 for water)
• (L) The length of the tube

Pipe Flow Rate (Q): The calculator return the volumetric flow-rate in gallons per minute.  However, this can be automatically converted to other volumetric flow-rate units (e.g. liters per minute) via the pull-down menu.

The Math

Poiseuille's Law equation for fluid flow rate through a pipe is:

     `Q = (π⋅ΔP⋅r^4) /(8⋅η⋅L)`

where:

• Q is the pipe flow rate
• ΔP is the change in pressure
• r is the interior radius of the pipe
• η is the fluid viscosity
• L is the length of the pipe