One way valve is there a kind like this?

[marokay]

Is there one way valve that allows a liquid flow in one direction and prevent air flow (under pressure) in the other direction?

Thanks for any help ...

 

[Nidum]

You could just look this up .

I'll give you some keywords :

Check valve
One way valve
Ball valve
Clack valve
Non return valve

 

[Vedward]

There are check valves with resilient seats which will accomplish this.

 

[Rx7man]

Does the valve have to differentiate between liquid and gas (air)? does it have to allow liquid to flow back but not air?

if it can allow liquid to flow back but not air, depending on the pressure you could have a floating ball on top of an orifice, when the flow reverses the ball will stay floating until the liquid level drops, at which point the ball will cover and seal the orifice. if neither liquid or gas need to be allowed to backflow, pretty much any of the valves Nidium listed would work fine.

 

[russ_watters]

Trap.

 

[JBA]

Here we go again, trying to help people that refuse to post enough information to actually have a possibility of getting appropriate answers from forum members.

 

[Nidum]

@marokay

You have asked this question previously on PF and on at least one other forum . Each time you have had useful answers .

This seems to be your actual problem :

The water is in a tank and I want them to flow through a pipe at the bottom of the tank (by the force of gravity)
Now I do not want that air will enters the tank back form the pipe while the pipe is open (in the pipe can be pressurised air)

It seems from this brief description that you want a valve with some active control features rather than one which is just self acting . This has been suggested before :

Active elements would be something like a sensor to detect water and open the valve based on that sensor.

If you would like to describe your problem more completely we could probably give you some better answers .

 

[CWatters]

Marokay - you asked virtually the same question on this forum over a year ago. Have you considered giving up on the project?