High Pressure Shutoff Valve? 1

[lowedogg]

Does anyone know of a spring loaded (or other type) valve that will permit flow at a low pressure and then shut off when the pressure increases? I know this sounds counter-intuitive, but here is my basic problem:

I have a pipe that will be exposed to freezing, but I cannot heat trace it. I am considering putting in a control valve to drain the pipe when it is not active, but if there is a simple mechanical device it would save me a lot of controls dollars. The drain must be closed when the pump is on and open when the pump is off. So, the valve would open in the direction of flow under low pressure and close when that pressure increases.

Anybody know of any such gizmo? If so could you direct me to the manufacturer?

 

[JLSeagull]

An excess flow valve works somewhat as described. The excess flow valves that I would buy are for tubing but they exist for process lines too. They function as protection to close a valve in the event of a line break.

 

[lowedogg]

Thanks! Googling it now. This appears to have me going in the right direction...

 

[lowedogg]

I haven't been able to find an excess flow valve for hydronic duty. everything is either for natural gas, compressed air or other industrial gases. Do you happen to know of anyone that makes an excess flow valve for water?

 

[unclesyd]

I would check with Ross about your requirements. We used their valves on several water systems but in what capacity I don't recall.

http://www.rossvalve.com/home.html

 

[Joesteam]

I used to work for a company GESTRA, now part of Flowserve. I no longer work there but that is another story, still like their products.

They make a valve - AK-45 - that does exactly what you are looking for, opens at low pressure and closes on high, used for freeze protection.

check out:

http://www.flowserve.com/vgnfiles/Files/Literature/ProductLiterature/FlowControl/Gestra/810467.pdf

Joe Lambert

http://www.control-associates.com/

 

[khardy]

how large a drain do you need? If small, how about a solonoid valve which is normally open. Wire it in series with the pump control circuit. If it's a small pump you may be able to put it in series with the pump's power circuit. Can't get much simpeler than that.

 

[thewellguy]

You could also look at Valmatic. An air vac release valve may also would.

 

[SteveWag]

Gorman-Rupp makes a valve like that for use as an air vent during start-up of their self-priming pumps. It has no storage chamber so if it were to freeze nothing would break.
Steve