Check Valve for Low Pressure

[FranciscoG]

I am looking for a 12" check valve for Methane at low pressure. Pressure of line is 8" Water column. It is a Biogas installation.

Any idea???

 

[MikeHalloran]

A 12" diameter vertical pipe at least 16" long, with the distal end submerged 1/4" in a pool of water...





Mike Halloran
NOT speaking for
DeAngelo Marine Exhaust Inc.
Ft. Lauderdale, FL, USA

 

[FranciscoG]

Thank you Mike, but I don`t understand the configuration

 

[zdas04]

I'm not certain I understand Mike's solution either, but the glimmer I got looks like an elegant solution to a very difficult problem.

FransiscoG, what are you planning for the check valve to do? Could the task be accomplished with a compressor-discharge check? Any swing check will require something on the order of 6" H2O to open, and in a 12" pipe it is probably more. Your stream doesn't have any extra energy to waste in operating a check valve unless it is crucial to the operation.

David Simpson, PE
MuleShoe Engineering

http://www.muleshoe-eng.com

Please see FAQ731-376 for tips on how to make the best use of Eng-Tips Fora.

The Plural of "anecdote" is not "data"

 

[FranciscoG]

I need to restrict the flow to one direction, I can not accept backflow, and I don´t have more pressure.

 

[JimCasey]

Mike's solution is basically the same thing as a P trap used to keep sewer gas from coming back up the plumbing. Very clever.

Companies like Groth, Protectoseal, and Varec make low pressure vents that start opening at around 1/2 ounce/in2. AN inline vent might be your best bet for a mechanical valve.

 

[MikeHalloran]

A little more detail:

Imagine a lift check valve, the kind you make from barstock. Ports on either end, coaxial. Communicating holes toward the center, one drilled up, one drilled down.
At the center, a blind hole drilled from the top to intersect the lower communicating hole, and a counterbore at the top, intersecting the upper communicating hole. Ordinarily, you'd put a lifting poppet and maybe a spring in the counterbore, then cap it. Forget the poppet. Forget the spring. Just cap the body.

Now, invert it, and fill the counterbore with water.

Gas flowing in the forward direction of the former lift check valve depresses the water level and bubbles out to the discharge port.

Gas flowing in the reverse direction tries to do the same thing, but can't lift the water in the deep vertical drilled hole, because there isn't enough pressure to lift the water that far.

Ergo, check valve, with no moving parts other than the gas and the water.

You might have to replenish the water.




Mike Halloran
NOT speaking for
DeAngelo Marine Exhaust Inc.
Ft. Lauderdale, FL, USA