CV list for various valves:

Post questions and info about pneumatic (compressed gas) powered launchers here. This includes discussion about valves, ratios, compressors, and anything else relevant to launchers powered by compressed gas.

Postby boogieman » Tue Nov 11, 2003 9:55 pm

The purpose of this topic is to get an estimate on some common valve parameters. These parameters will help with designing and comparison of different valves.

Please list any known info, or theorized info.

It would be nice if the following info could be gatered: CV, Open/Close time, Dwell time.

Let me know if i am missing any useful parameters...
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Postby pacogoatboy » Wed Nov 12, 2003 10:07 pm

These numbers are entirely from what I've read on this site and others, and I take no responsibility for their accuracy or lack thereof:

For a 1" sprinkler valve, electrically actuated, I use:
Cv=6, Open/Close=12 ms, Dwell=1000ms

1", Pneumatically actuated:
Cv=6, Open/Close=4 ms, Dwell=1000ms
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Postby boogieman » Thu Nov 13, 2003 12:02 am

for a 1" watermaster pneumaticlly modded(from spudtech): i used the following with the help of bartman:

Type: generic
CV:5.8
open/close time(ms):10
Dwell time(ms):1000

I got a chronied shot of 615 fps, so it was dang close...

After much testing I realized I could get around 618fps with this gun, so i made some adjustments to the valve parameters. With this setup ggdt shows my launcher topping out at 618fps:

Type: generic
CV:6.15
open/close time(ms):10
Dwell time(ms):1000

I do not know if those number are 100% accurate(they are a combination of ggdt and actual chronied results). But they should give very close results on a small bore gun.

p.s. if anyone has a supah they are willing to donate, i will gladly do some testing with my chrony;)[:p]
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Postby Duster » Thu Nov 13, 2003 12:24 am

anyone willing to do one for one of those non-inline 3/4" valves for me? lol I got a bunch (4 or 5 or so) extra ones so....
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Postby boogieman » Thu Nov 13, 2003 1:09 am

lol sure, send them! just email me (adress on my profile). I could just use the coke gun and make it go to 3/4". Just send return postage and I would be glad to. The reason I am so eagar to test them is that it would fit the coke gun with little or no modification. :)
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Postby mta » Fri Nov 14, 2003 12:26 pm

Here are the results on my 1.5" x 3" and 2" x 4" coaxial floating diaphragm guns
based on the plans at spudzooka.net. Bottom line: Cvs of 21 and 43.

A diagram of the smaller gun can be found here:

http://mywebpages.comcast.net/glenshind ... ternal.gif

Photos of the larger gun can be found here:

http://w3.mivlmd.cablespeed.com/~mta/spud/


Gun 1: Built almost exactly to spudzooka.net specs: 1.5" sch40 rifled
barrel 72" long. 3" sch 40 chamber 43 inches long. Volume ~ 185 cu.
in. Floating diaphragm valve. 1/4" quick exhaust.

Chrony results with 100 gram projectile (duct tape wrapped) and CO2 as
the gas:

PSI FPS FPE
040 240 198
050 260 231
060 310 330
070 326 357
080 365 456
090 389 518
100 401 550

<B>GGDT models this gun pretty well with a Generic valve, Cv = 21, open
/close time = 10 ms, dwell time >100 ms</B>



Gun 2: Just like gun 1, except 2" sch40 rifled barrel 118 inches long,
4" sch80 chamber 73 inches long. Volume ~ 500 cu. in. Floating
diaphragm valve. 3/8" quick exhaust.

I have not chronied it as extensively as the first gun, but I can
report with a 170 gram projectile (wrapped in duct tape) and CO2 as the
gas:

PSI FPS FPE
100 503 1474
110 520 1576


<B>GGDT models this gun pretty well with a Generic valve, Cv = 43, open
/close time = 10 ms, dwell time >100 ms</B>
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Postby gyroman79 » Fri Nov 14, 2003 10:30 pm

How does one simulate dual valves in GGDT? Part of my brain tells me to just double the Cv, but another part says that doesn't sound right.
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Postby andeh » Sat Nov 15, 2003 7:31 am

Just double the Cv.
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Postby Bartman007 » Mon Nov 17, 2003 4:29 am

yeah, double the Cv, double the fun!
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Postby Spudlauncher » Thu Nov 27, 2003 9:52 pm

How do you find the Cv of a valve?
or what is Cv?
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