Adjustable vacuum release valves?

[1PE]

Are there adjustable vacuum release valves?

What I mean is "Can a valve be set to remain closed at negative pressure of 11 psig and open at say negative 15 psig.

The application involves a siphon that will operate at a negative pressure at the apex. I'm concerned the pipe will collapse when the siphon is "broken".

 

[paulyg]

There used to be valves some vales that would serve your function via use of springs or counterweights. I recently had to try and find a replacement for such a valve and could not come up with anything that was self contained (ie could sence the vacuum and then open). I ended up using an adjustable vacuum switch connected to a solenoid operated valve which acts as a vacuum breaker.

- Paul

 

[abcmex]

1PE,
there are several companies producing this kind of devices:

http://www.protego.com

http://www.protectoseal.com

Look in

http://www.che.com

, buyers guide, under "Valves, vacuum relief" about 50 suppliers.

I hope you do not really need minus 15 PSI, it is below absolute zero ;-)
RGS

 

[TylerJett]

abcmex is correct, being minus 14.7 PSI is a full vacuum. Crispin Valve has done this in the past. It is done using a vacuum relief valve with a spring sized specific for the negative pressure. Hope this helps.

 

[scooter911]

There call vacuum breaks, we've turned relief valves around and they work well but flow is low until the delta pressure can open the valve. The solenoid on a pressure switch works really well and if it's critical put redundant switches and valves in. The solenoid way is fairly economical and easier to calibrate if you have to do it on a time schedule.

Working with a lot of vacuum, I can really say my job sucks.

 

[kryogenus]

Actually, check out a company called ANVER. They have three sizes available (all FNPT) that can be set between 7" and 16" Hg.