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schrader opening pressure

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 opening pressure

Unread postAuthor: Anatine Duo » Fri Mar 07, 2014 10:06 pm

Has anyone tried modifying a schrader so that it cracks open at lower pressure?

I have a 1/8 snifter valve that cracks at about 3psi but tire valves crack open about 60... Is it just the spring?

I like the idea of using them as check valves.
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Re: schrader opening pressure

Unread postAuthor: jrrdw » Sat Mar 08, 2014 7:00 am

Adjusting the spring on your everyday standard schrader valve will be a tall order. The core springs are covered with thin cupped brass or copper parts and seals that if damaged you will more likely than not cause a unstoppable leak.

One good thing about your idea is they are cheap so it won't break your bank experimenting.
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Re: schrader opening pressure

Unread postAuthor: Gippeto » Sat Mar 08, 2014 10:04 am

The only ones that can be readily modified are those having an external spring like this;

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Re: schrader opening pressure

Unread postAuthor: jackssmirkingrevenge » Sat Mar 08, 2014 10:15 am

You could always use a presta valve.
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Re: schrader opening pressure

Unread postAuthor: Anatine Duo » Wed Mar 12, 2014 12:27 pm

turns out there are low-opening-pressure-cores manufactured by Schrader but I haven't sourced the yet except as part of a large kit

but modifying existing ones is not going well... maybe rip out the spring and use an external spring (or gravity) to close it
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Re: schrader opening pressure

Unread postAuthor: Tipsypyro » Wed Apr 09, 2014 12:49 pm

There are springless schrader valves that close on air pressure only they use for putting pressure on water supply systems in homes. They are very compact as well and go in on a 1/8 npt thread. They cost about $3.00 apiece at a plumbing supply store.
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Re: schrader opening pressure

Unread postAuthor: bravootome » Mon Apr 14, 2014 12:32 am

Anatine Duo wrote:Has anyone tried modifying a schrader so that it cracks open at lower pressure?

I have a 1/8 snifter valve that cracks at about 3psi but tire valves crack open about 60... Is it just the spring?

I like the idea of using them as check valves.



i mod. the schrader valve. i removed the spring and cut of the little pin. so it is only operated by the pressure itself . This way you wont loose pressure from the tank when you unplug the pump...
so far it hold 35 bar.
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Re: schrader opening pressure

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