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Schrader Valve Flow Cv

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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Schrader Valve Flow Cv

Unread postAuthor: cammyd32 » Thu Oct 17, 2013 3:37 pm

Unable to produce the tests to generate my own data, I've been scouring the internet for some time looking for some raw data that I could use to calculate flow coefficient of a simple Schrader valve for quite some time.
After my searches being fruitless for quite a while now recently I found a single piece of information that helped me:
Flow rate through Schrader valve with 8bar supply pressure= 157L/min (2.6L/s)


Initially used on a forum for calculating something or another to do with homemade scuba gear,* or something of the sorts, the test compromised of putting constant pressure through a fully opened Schrader valve and timing how long it took to fill a 20l bag.

By converting the units to cubic feet per hour, and thus by using using the equation "Cv = q [SG (T + 460)]1/2/ 660 pi" (thank you engineers toolbox) I got the result:
0.12

Which should make the Cv of a schrader valve out at around: 0.12

As soon as I can get my own equipment to test the valve coefficient accurately and so get a more reliable figure for it I will, but until then this makes a good alternative to simply guessing a Schraders valve coefficient, and would be a better than guestimate figure to put into GGDT or the equivalent for people attempting to simulate a Schrader valve in their design.
Alternately if anyone has a good alternate value (and tells me I am massively wrong) I would love to hear it, as searches have returned nothing, even from schraders own site, and the data I have used is less than reliable for the function I used it for.

Thankee all :)

*There were other results that were posted, but the others had different variations in connection and had some manner of restriction between the valve and the tank so I decided to disregard these
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Re: Schrader Valve Flow Cv

Unread postAuthor: jackssmirkingrevenge » Fri Oct 18, 2013 7:46 am

Nicely done!
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Re: Schrader Valve Flow Cv

Unread postAuthor: Gleedaniel13 » Mon Oct 21, 2013 8:47 pm

Unable to produce the tests to generate my own data, I've been scouring the internet for some time looking for some raw data that I could use to calculate flow coefficient of a simple Schrader valve for quite some time.
After my searches being fruitless for quite a while now recently I found a single piece of information that helped me:

Flow rate through Schrader valve with 8bar supply pressure= 157L/min (2.6L/s)



Initially used on a forum for calculating something or another to do with homemade scuba gear,* or something of the sorts, the test compromised of putting constant pressure through a fully opened Schrader valve and timing how long it took to fill a 20l bag.

By converting the units to cubic feet per hour, and thus by using using the equation "Cv = q [SG (T + 460)]1/2/ 660 pi" (thank you engineers toolbox) I got the result:
0.12

Which should make the Cv of a schrader valve out at around: 0.12


This is very amazing having this incredible things done. :lol:
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