floater ball valve for vacuum service
floater ball valve for vacuum service
(OP)
I searched for similar questions but i couldn't find a clear answer.
I have a 1" floater ball valves size and the operating pressure will be (-15) psig on one side and atmospheric on the other side
is this going to work? thanks in advance.
seats are teflon
and stem seals type is packing
I have a 1" floater ball valves size and the operating pressure will be (-15) psig on one side and atmospheric on the other side
is this going to work? thanks in advance.
seats are teflon
and stem seals type is packing





RE: floater ball valve for vacuum service
I believe there are specific valves used for vacuum service which are not standard floating ball design.
http://www.sharpevalves.com/pdfs/Engineering/SPD01...
http://valveproducts.metso.com/documents/jamesbury...
It does seem to vary on exactly how low your vacuum is.
Remember - More details = better answers
Also: If you get a response it's polite to respond to it.
RE: floater ball valve for vacuum service
so if the operating pressure is -15 psig absolute it doesn't matter, all it matters is the differential pressure because that's how the seat gets energized?
RE: floater ball valve for vacuum service
Vacuum with dP actuated floating ball valves is a very counter-intuitive undertaking. If you see a situation that just makes no sense (and you likely will), don't ask "how did this happen" ask "where can I apply a(nother) band-aide. I've spent days and days of my life asking "how" and always ended up asking "can I patch this mess and get on with my life".
David Simpson, PE
MuleShoe Engineering
In questions of science, the authority of a thousand is not worth the humble reasoning of a single individual. Galileo Galilei, Italian Physicist
RE: floater ball valve for vacuum service
basically the difference between inlet and outlet pressures is the .145 psi ? but in this case there will hardly be any flow? and is that enough pressure to push the ball against the downstream seat?
another thing is if the guage pressure at inlet is .145 psi = -14.5 psia , then the pressure is reversed?
RE: floater ball valve for vacuum service
I take the experience that ZDAS04 gave, viz once you loose surface finish on the ball, game over. So this gets back to how often you operate the valve. In a high cyclic operation I think that you will be changing out valves on a regular basis. The crush on the seats will not last for ever. You could look at harder seat materials but that will also make getting the seal more difficult.
Good luck, be interested to hear how you go!
RE: floater ball valve for vacuum service
When we first took a natural gas field on vacuum, stem seal leaks were a major problem. The only way we were able to identify them was with a "bee smoker" (you know the devices that bee keepers use to quiet the hive while collecting honey), and we found that many stem seals on older valves leaked. New valves often had to have the stem seal adjustments tightened, but almost all of them could be made to hold. With the older valves, we replaced the packing/o-rings and were generally able to make them tight. Virtually all of the valves in our field were three piece threaded construction. We didn't ever see a leak in the body threads.
David Simpson, PE
MuleShoe Engineering
In questions of science, the authority of a thousand is not worth the humble reasoning of a single individual. Galileo Galilei, Italian Physicist