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check valve

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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check valve

Unread postAuthor: Sticky_Tape » Tue Mar 11, 2008 7:23 pm

I am thinking of building a high pressure pump and I am wondering where to get a check valve and I know prices are different everywhere but what is the aproximate price for one?
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Unread postAuthor: elitesniper » Tue Mar 11, 2008 7:33 pm

depends what sizes
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Unread postAuthor: Sticky_Tape » Tue Mar 11, 2008 7:40 pm

anything that will fit on 3/4 inch pipe.
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Unread postAuthor: elitesniper » Tue Mar 11, 2008 7:43 pm

well a metal one around 12 bucks US
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Unread postAuthor: Sticky_Tape » Tue Mar 11, 2008 7:46 pm

well thats typical
what about one thats 1/4 inch?
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Unread postAuthor: the cats in the bag » Tue Mar 11, 2008 7:52 pm

There are many places you can by high psi check valves including sprinkler ware house, and even lowes depending on psi.. but what psi range do you want?
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Unread postAuthor: Hawkeye » Tue Mar 11, 2008 8:00 pm

It is not rocket science. The check valve seems to stymie pump makers when it is simple to just assemble a few parts. All you need is a reducer that has a sharp transition in diameter so that a lip is on the inside, something like a nail with a large flat head , an o-ring and a spring.
Slip the o-ring on the nail. Put it inside the reducer so that the o-ring seals against the lip. Put the spring behind the nail. Thread together.
Exhausting work.
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Unread postAuthor: Sticky_Tape » Tue Mar 11, 2008 8:06 pm

Hawkeye wrote:It is not rocket science. The check valve seems to stymie pump makers when it is simple to just assemble a few parts. All you need is a reducer that has a sharp transition in diameter so that a lip is on the inside, something like a nail with a large flat head , an o-ring and a spring.
Slip the o-ring on the nail. Put it inside the reducer so that the o-ring seals against the lip. Put the spring behind the nail. Thread together.
Exhausting work.

What did that say I can't quite make out what you just typed it's a little un illistrated.
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Unread postAuthor: Sticky_Tape » Tue Mar 11, 2008 8:23 pm

I was thinking about somthing like this there is sheet metal sandwiched between two unions and a 3/8 inch ball barring as the ball
BTW sorry for the double post.
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Unread postAuthor: Hawkeye » Tue Mar 11, 2008 9:03 pm

I haven't a clue how to do an illustration.
Let me try again: A reducer goes from one size to another. There will be a transitional step where the size changes. If you insert a nail in the larger side it won't be able to be pushed through because the head will catch. Add the o-ring and it will also seal. Put the spring behind the nail head to hold it shut. When you push down on the pump, the nail will unseat and allow air in and then the spring and increased pressure will seal it again.
The reducers with the best lip on the inside are 1/4" male-3/8" female and 1/8"-1/4" male-female or male-male.
Kinky as that sounds.
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Unread postAuthor: lockmanslammin » Wed Mar 12, 2008 4:14 am

here is a check valve I put together from parts I got at Ace Hardware.
It has some perty crappy drawing on it,but I was in a hurry and I'm trying to get used to a laptop. This is all 1/8" pipe fittings in brass. In the mcmastercarr catalog fittings like these are rated at 1000PSI. The ball is a ball bearing, I don't know what size it is but it fits nicely inside that female to female coupling. the spring slides inside the 1 1/2" long 1/8" pipe nipple like it was made for it. The elbow is just a way to compress the spring slightly. the oring presses against the inside of the coupling and the face if the hex pipe nipple.
I have tested the setup to 300PSI so far, and it has worked perfectly. But, honestly if your more patient than me and willing to order something online Mcmastercarr has check valves that probably cost like a dollar more and are purpose made. I just wanted the check valve right away and honestly just like to build stuff.
Also if your going to build a high pressure pump, use a floating oring design. they are simple and work well. The only other thing I will say is don't underestimate the importance of keeping dead air space to a minimum.
Good luck,
Lock
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Unread postAuthor: MaxuS the 2nd » Wed Mar 12, 2008 5:47 am

You could just buy one.. Why are you complaining about $12? A check valve over here cost $40.

It gauranteed to work better than your own.
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Unread postAuthor: Sticky_Tape » Wed Mar 12, 2008 7:36 am

come on 12 dollars for a check valve it's like 12 for the piece of 3/4 inch copper pipe.
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Unread postAuthor: Hawkeye » Wed Mar 12, 2008 8:12 am

Total cost of mine, about 6 dollars. If it works flawlessly there is no way a commercial one works way better.
Two small brass threaded fittings, a nail, 0-ring and ball point spring can only cost so much.
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Unread postAuthor: MaxuS the 2nd » Wed Mar 12, 2008 10:41 am

A check valve comes with a gaurantee, you don't need a 3/4" check valve because you've got 3/4" pipe. A 1/4" valve will do fine.
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