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How do I figure valve coef in GGDT?

Post questions and info about pneumatic (compressed gas) powered cannons here. This includes discussion about valves, pipe types, compressors, alternate gas setups, and anything else relevant.
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How do I figure valve coef in GGDT?

Unread postAuthor: Jeeperforlife » Thu Dec 03, 2009 6:24 pm

I understand all of the other parameters in GGDT well enough to trust the out come except this. How would I figure it? The gun I am currently modeling is a coaxle with 4" chamber 2" barrel with a o-ring sealed piston and a 1" modified sprinkler valve dumping it. Piston weight is about 1 lb.

Also how do I save the screen shot to show here.

Thanks,
Marcus

Edited by jrrdw.
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Unread postAuthor: jmadden91 » Thu Dec 03, 2009 6:30 pm

Just use the print screen button then post the image.
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Unread postAuthor: POLAND_SPUD » Thu Dec 03, 2009 6:48 pm

you can find info on this here but it won't tell you much (at least it doesn't tell me much)

manufacturers often give Cv or Kv values of their valves... try to model this 3/4"QEV (it's on the 6th page) using the Cv value given there...

if you model it correctly and switch from Cv to efficiency GGDT will convert that value into ~47%, which is said to be what QEVs can achieve
(not that I understand flow coefs but I wanted to show that you can sometimes find flow coefs of valves in their data sheets)

EDIT
sorry, I messed up the link
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Unread postAuthor: Jeeperforlife » Thu Dec 03, 2009 11:49 pm

Thanks I think I will just leave it with what GGDT has as a standard.

Thanks,
Marcus

Edit, I figured the Print screen out. I did not realize I had to save it in a different program.

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