Using A Valve With A Larger Diameter Than The Barrel

[n05gr0th]

Hey guys, I have a question for you.

What would the performance be like for a 3/4 QEV affixed to a 1/2 in barrel when compared to a 1/2 QEV for the same barrel diameter? What would the airflow be like with the larger valve feeding into a smaller barrel? Would it increase power, remain the same, or actually be detrimental to performance?

P.S. Anyone know if European style QEVs are available with NPT threads?

Many thanks!

[Technician1002]

In high flow situations, a small valve will have a pressure drop on it. This effectively lowers the pressure to the barrel. A larger valve will have a lower pressure drop resulting in higher pressure to the barrel. How much change between the valves, I don't know. In a larger valve with a small barrel, air velocity is reduced in the valve resulting in less shock waves in the valve and again less pressure loss.

Note that a 1/2 inch QEV does not have a 1/2 inch valve seat, so there is a considerable restriction to flow built in. A valve wide open does not have the same flow capacity of a piece of pipe the same size.

There is already a similar topic on this subject. http://www.spudfiles.com/pneumatic-cann ... 25936.html

[n05gr0th]

I appreciate your response. Thanks for the link!