# head pressure = how much flow

J
Thread Starter

#### Jaems

I might have posted this in a wrong category, if so, sorry.

I'm a little curious, can I figure out how much flow i will have in a 1/2" tube that has 2 meters of water head pressure?

I have no fluid background, but I sure this is an easy question for some of Control.com members.

Thanks,
James
Instrument Mechanic

B

#### Bruce Durdle

1). Easiest way - ask a process engineer or similar with access to piping loss software.

2). "Beat yourself to death" way - from details of the fluid density, viscosity, pipe diameter and an initial assumption of flow, calculate the Reynolds' Number. Use this on a Moody Diagram to find the friction factor f. Plug this into the head loss equation h = f (L/d) (u^2/2g) where h is your 2 m head, L is the length of pipe, d is the diameter, u is the velocity, and g is g. Fund u and reassess your original flow estimate - repeat until you converge.

Method 1). is my preference - but you can probably find some free software out there to do it for you. Google "Moody Diagram".

Cheers,
Bruce.

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