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Diaphragm thickness

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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Diaphragm thickness

Unread postAuthor: limbeh » Fri Apr 16, 2010 12:51 am

Thinking of building my own diaphragm valve.

Read up on the spudfiles wiki, and apparently 1/4" neoprene is common.

My problem is this: how much thickness for a max pressure of 180psi? Too thick and diaphragm probably won't even flex.

Haven't been able to find any other stuff that I could refer to so far, but am looking up to see if anyone posted any diaphragm cannons up there.

Thanks.

Limbeh
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Unread postAuthor: jackssmirkingrevenge » Fri Apr 16, 2010 12:57 am

Depends on the diameter of your chamber and barrel, sprinkler valve diaphragms are usually well below 1/4" thickness.
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Unread postAuthor: limbeh » Fri Apr 16, 2010 6:05 am

Internal Diameter of chamber: 48mm
ID of barrel: 16mm
OD of barrel: 22mm

Unfortunately, since gardens are pracitcally non existent here, lawn sprinklers and sprinkler valves are also pretty hard to find here, so I can't really refer much to them. However, the idea of 6mm thick neoprene seems like waaaay overkill.....

Thanks.

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Unread postAuthor: jackssmirkingrevenge » Fri Apr 16, 2010 6:13 am

If I remember well a typical 3/4" sprinkler valve has a diaphragm less than 2mm thick.
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Unread postAuthor: limbeh » Fri Apr 16, 2010 6:45 am

So that should mean that 3mm should be enough.

Thanks.
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Unread postAuthor: jackssmirkingrevenge » Sat Apr 17, 2010 2:34 am

A couple of diagrams form the archive that might be of some help:
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DIAPHRAGM ANIMATION.GIF
diaphragm gun cutaway.JPG
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Unread postAuthor: limbeh » Sat Apr 17, 2010 10:38 am

Thanks for the diagram, though I already found a diagram on the spudfiles wiki.

By far I don't find the working principles of spudguns hard to understand, its constructing it without much time, tools or working space that's the hard part.

Thanks.
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Unread postAuthor: psycix » Sun Apr 18, 2010 10:36 am

The first diagram (animated one) will not work that way.
When you pilot it the sealing face will flap into the back.
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Unread postAuthor: iknowmy3tables » Sun Apr 18, 2010 8:07 pm

the thickness need is really going to vary, most people don't bother finding the perfect thickness for a diaphragm, many people just glue the edges of the rubber disk to the wall of the chamber or even clamp the disk in a union, then they reinforce the area behind the barrel/port with a solid disk so the diaphragm wont burst at that area, this way it doesn't matter if the rubber can withstand the full pressure as long as the disk backing the rubber can
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Unread postAuthor: Gun Freak » Sun Apr 18, 2010 8:31 pm

Jack, your diagram is full of DWV :roll:
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