Hi all! Someone here could help me

[GerryJ]

Hi all!
Someone here could help me where this equation came from? what books or standard books?

 

[LittleInch]

Give us a bit of a clue as to what it relates to.

Looks to me like a relief valve calculation.

Set up for air flow maybe.

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[mk3223]

It’s the typical piping flow equation of the compressible fluid, which may be referred to the Fluid Mechanics or Flow of Fluids by Crane.