Hi everyone

I understand when valve closure time is less than 2L/c, we can analyze the system in dynamic mode, or using DLF=2 in static mode. But what do we do when T>2L/c? Is it ok to ignore the water hammer? The pressure surge can still happen and will be considerable (i.e. equal to 2L.ro.V/T). That will be good if someone could shed some light on this.

Thanks
Bobby

We have 2 phenomenons.
First Joukoswki dP at criterium T < 2L/c.

Second at T > 2L/c take the simple Newton rule.
dP = rho * L * dw/dt
rho => fluid density
L => pipe length from the surce
dw => change of velocity
dt => time different (change of velocity)

Thanks Ohliger. Does that mean we dont consider water hammer if the timing is larger than 2L/c?

Thats mean formal is it not a water hammer case.
And that mean it is no dynamic effect, so the loads and stress in the pipe
very lower as in the case water hammer.
Wether you the Newton case calculate is your decision.
Usually this case will not calculated.