Please give me answer for pipe Inner diameter calculation from Flow rate.?

Question

We have the Water flow rate 20 l/s please reply me the fornula for caculate the pipe diameter,

Answer 1

Q=AxV

Q- Discharge of fluid

A- Area of pipe

V- Velocity of flow

Answer 2

You have an equation with 3 components:  Q=AV

Q - [volumetric flow rate], known

A - pipe cross-sectional area [a function of your inner diameter as A=pi * (d^2) / 4], unknown

V - slug velocity of the water, unknown

So you have 1 equation, 2 unknowns.  You cannot solve without more information.  

Bomba makes a good assumption, but I can probably find a pump that will allow us to get 20l/s in a variety of pipe sizes.

Answer 3

Edited

Q=AV will work if you also know the velocity.

You are looking at 20l/s which is about 300 U.S. gallons/minute. The piping selection tables show that a pipe of 4" nominal size standard wall thickness will produce a reasonable velocity of 8 ft/sec with a friction loss of about 2 pounds for each 100 ft. of pipe. The inside diameter is slightly over 4". This would be typical for a mechanically pressurized system (pumped) or one with sufficient static pressure from an elevated reservoir. Of course smaller pipe will result in higher velocity and much higher pressure loss. For instance a 3" pipe will have about twice the velocity and about four times the pressure loss. That may be acceptable for short runs.

If gravity flow or a long piping distance at low friction loss is the application, the next larger nominal pipe size is 6" with an inside diameter of slightly over 6".