Water Hammer, ESD valves
Water Hammer, ESD valves
(OP)
Hi All
Does anyone know of a formula for calculating the minimum closing time of an ESD valve to prevent water hammer?
PSV upstream so Pressure wave would make it lift. My limitation is Pset in PSV.
Safety guides advice travel time of ESD valves in service should normally not exceed 2 sec/inch (valve size).
Regards
Does anyone know of a formula for calculating the minimum closing time of an ESD valve to prevent water hammer?
PSV upstream so Pressure wave would make it lift. My limitation is Pset in PSV.
Safety guides advice travel time of ESD valves in service should normally not exceed 2 sec/inch (valve size).
Regards





RE: Water Hammer, ESD valves
RE: Water Hammer, ESD valves
How long pipeline and how high pressure?
And in addition: in some systems ESDs is set to close in two steps: fast to about 70-80% closure, then longer to throttle at slower speed.
RE: Water Hammer, ESD valves
An ESD would be operated in the event of circumstances presenting a risk to a system or facility. Measures taken in an ESD must not produce events that are of equal or greater risk than the first occurence. Guessing a closing time is open to claims of negligence.
Suggest you read up on surges. Go to www.pipingdesign.com and review the papers on that sight.
RE: Water Hammer, ESD valves
I am reviewing why some ESDs in the plant affect to some equipment (psvs, rupture disk,etc) and why others dont.
in the example case I was checking, the pipe to the psv is 1003m, and its Pset is 37,5 bar.
I have checked Joukowsky equation, to estimate the appropiate closure time roughly. It works for water, but gives funny numbers for hydrocarbons (liquified ethane, in the example) Any other formula which would be able to give an initial approximation?
on the other hand, it is not easy to find bulk modullus for liquified hydrocarbons. Do you know any useful site to check them?Thanks again
RE: Water Hammer, ESD valves
For bulk modulus data invest in Chempak from www.aft.com. It is only a few hundred dollars and covers 700 chemical fluids. You can even put in mixtures to get up to 15 parameters.
If you use their software Impulse for transient analysis then you only need the database. If not, you need the front end software or Excel interpeter.
Impulse is written by engineers who came from the petrochem industry rather than the water industry so you will find that their support is more in tune with your challenges.