This thread came just at the right time, I ordered a Festo fitting check valve from Troy buil models ( excellent service by the way [8D] )and other stuff with it, I was thinking this was the one way Festo fitting valve that was like the ones you get with your turbine install package but that is not the case and this thread confirmed that.

The Festo check valve will allow the fluid or gas to flow both ways if you insert a line on both ends, disconect the correct line and now the check valve is working by not allowing the fluid or gas to scape.
The Festo one way valve with lines on both ends allows fluid or gas to travel one way only, this is the valve fitting that we get with the install package for our turbines and it's used for the Propane in line to the Prop can.

The valve that Gordon mention is a nice one 'cause you can regulate the amount of gas/air/fluid at any time.

Now I understand thanks again to all of you guys and RCU where we always find the answers.