Question on low residual pressure in water main
Question on low residual pressure in water main
(OP)
I've read that the residual pressure in water mains needs to stay above 20 psi in order to prevent pipe collapse. Why would pipe collapse at 20 psi residual?





RE: Question on low residual pressure in water main
Therefore the AWWA and most state EPA branches have requirements that if the pressure goes below 20 psig, a boil order has to be issued.
If the suction goes down even further, it could cavitate the pump, or at worst case, supposedly it could collapse the main, but I do not think a centrifugal pump could create enough suction to do that.
On fire pumps, often there is a requirement for a pressure sensing valve which will actually throttle the discharge of the fire pump so the suction is never less than 20 psi. On domestic booster pump, there is often a sensor that prevents this.
RE: Question on low residual pressure in water main
Look at thread184-342887: Problem with a project and in need of input from a FPE or knowledgeable PE. for more information.
You could also do a search on the site for other threads which could shed light.
RE: Question on low residual pressure in water main