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Fluid Flow Calculator
by Michael J. Rocchetti PE
Mechanical Engineer

This calculator is used to calculate pipe friction losses for straight piping handling water and water with varying percentages of ethylene glycol. The calculator uses an algorithm developed from the basic principles of fluid mechanics. The program is based on the Darcy-Weisbach equation, the Colebrook equation, and the Moody equation. The program is intended for use only on straight piping. The program does not include pressure losses due to elevation differences, or flow through fittings.

This calculator allows you to input the fluid type, the fluid temperature, the flow rate, the pipe size, pipe length, and pipe material. The calculator then determines the velocity, the Reynolds number, the Moody friction factor, the pipe friction factor (from the Colebrook equation), the pipe head loss, and the pipe friction loss in PSI. This calculator is intended for use on systems handling water and water with varying percentages of ethylene glycol.

Please note that this method works for turbulent flow situations where the Reynolds Number is greater than 3000. If you find that your Reynolds number is less than 3000, you should revise your input parameters (increase the flow rate and/or reduce the pipe size).

Additional Design Criteria: If your piping is being used in an open loop system, flow velocities should be in the range of 5 to 10 ft/sec. For closed loop piping systems, you should use a 4 ft/sec limit for piping of 2" or less. For larger pipe sizes, use a limit of 4 FT of head loss per 100 FT of pipe.



Fluid Temp F:
Fluid Type is Water. Select a % of ethylene glycol
flow rate GPM:
Pipe Material:
Copper, type L
Steel, Schedule 40
Pipe Size:
pipe length ft:


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Last Updated on: 05/01/2003