Cross VS Tee Piston Valves

[clemsonguy1125]

If a piston valve was built in a tee and cross which would have greater power. The cross would have 2 2.5 foot 2 inch tanks and the tee would have 1 5 foot 2 inch tanks. At 75 psi wouldnt the cross have greater performance because it would have better flow. Assume both had the exact same pressure, piston, chamber volume and pilot valve. Wouldnt higher pressure remain throught the shot better with 2 short chambers than one long chamber.
Thanks Clemsonguy1125

[Technician1002]

Simple fluid dynamics would show that for a given flow in the barrel, the velocity in each half of a cross would be 1/2 that of a T.

Lower velocity in each half equals less losses. With the less losses in the cross, it can flow better. This is why I'm a fan of coaxial designs with large diameter chambers.

[spudtyrrant]

At 75 psi wouldnt the cross have greater performance because it would have better flow. Asume both had the exact same pressure, piston, chamber volume and pilot valve.

OK air can only flow through your port so fast, so if you built both of your cannons perfectly and to exactly the same specifications they should be exactly the same power wise. but only if they both have more flow than the port size. other factors may effect them such as turbulence, but that comes down to the quality of the build.

[clemsonguy1125]

Ok, I understand your point but with one chamber is it getting the maximum amount of flow that it could have with 2

[Technician1002]

A piston in a T has to open farther than a piston in a cross for the same cross sectional opening between the chamber and barrel. If both pistons opened at the same speed and same distance, the piston in a cross would be open the same cross section to flow in less distance.

In other words, it open more area to flow in the same amount of time. It effectively opens faster and then opens further.

[clemsonguy1125]

ok I think I understand, are you saying a cross piston would work better, or is the performance increase or decrease to small to notice.

[Technician1002]

I have not built either. How much performance change is there, I don't know.

I do know my latest valves have higher flow than average cof according to GGDT.

[clemsonguy1125]

Ok thanks, but what is cof

[spudtyrrant]

coefficient of flow, its how much flow your valve lets through

[clemsonguy1125]

Ok, Thanks

[Technician1002]

Coefficient of Flow. It is a measure of the ability to flow in a valve.

Low numbers is low flow.

http://en.wikipedia.org/wiki/Flow_coefficient

[Gun Freak]

Go with a cross, as said before it has some advantages. Plus it's only been done a few times before. Good luck.

[mobile chernobyl]

Cross valves just do it better...

[Technician1002]

Don't use a DWV cross. Use a sched 40 or better.

[Gun Freak]

Large crossed are hard to find in sch 40, maybe try an irrigation store.