Thumb rule for surge pressure calculation Thumb rule for surge pressure calculation extremechanical (Mechanical) (OP) 18 Oct 16 13:28 Hi could any tell, how to quickly approximate surge pressure due to valve closing or pump stoppage? Also I want to know if the surge pressure be more than pump dead head pressure due transients repetitions? Thanks a lot ! RE: Thumb rule for surge pressure calculation BUGGAR (Structural) 20 Oct 16 15:09 Nobody answered so here's a shot from the building industry. During a fire hydrant test, the hydrant valve stem failed and the valve slammed shut. The resulting (what we call) water hammer, caused an 8 inch sprinkler main in an adjacent building to drive itself and attached sprinkler laterals right out the end of the building. It was a wet system and system pressure could never approach that. A truly fantastic sight! RE: Thumb rule for surge pressure calculation DSB123 (Mechanical) 27 Oct 16 11:57 Use the Joukowsky equation - assume the flow is instantaneously stopped.