Dear All,
I have this question regarding effect of Surge pressure during Pump Start up.
As you see in attachment, it is a Foam Generator Pump that use to mix water and foam solution for Fire Fighting purposes.
New line is Tie in into existing line using Split TEe 8"x8" with Hot tapping pressure.
The consideration is effect of Surge Pressure at the Split Tee 8" x8" at the discharge side.
As we know for pump shutdown (pump trip), the suction side will experience Delta P = Fluid Density x Sonic Velocity x Velocity differential.
and the discharge side will experience Delta P = P discharge - Pvapour.
and we can calculate the Surge Pressure by = Delta P x A x DLF

That is for pump shutdown, Now the case is for pump start up, where the discharge line initially is empty, the suction line is filled with water. When the Pump start up the empty discharge line will be filled by Foam solution Plus water.

My question:

Can i consider Delta P at the discharge side = Fluid density x Sonic Velocity x Velocity differential....?
or doest the Delta P at discharge side is only equal to the operating pressure of pump discharge?
And does the Surge Pressure significant in the suction side??
Pleas enlighten me........

Please see attachment...