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How To Make a One-Way Check Valve - For Cheap!!

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It's summer. If you're going to build yourself a water-gun or a water pump, you'll need some check valves. These should work for you PVC building enthusiasts!

The most expensive parts of a water pump, or DIY Super Soaker, are usually the check valves.  In this project, we're making some from scratch, for as little as $0.35 each.
 
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Step 1: Watch the Video!



WARNING: The pressure tests and claims made on these check-valves is based solely on my personal experiences with the ones demonstrated in the video.  Individual results may vary, and caution and care should be taken when loading the valves with high pressure.  The risk of higher pressures is that the balls may be forced from the adaptor, shooting out like projectiles.  High pressures may also cause the ball to lock up, preventing normal operation of the valve, or possibly even structural failure of the valve altogether.  These valves are not made, or claimed, to be used in any heavy duty operations.  Use of this content is at your own risk.
TSJWang20 days ago

I love how you compared it to a diode!

HeyMister7 months ago
So, who makes that 3/4" slip to male thread adapter? It's not Lasco or Spears, and it absolutely makes a difference.

The O ring, is that a 12? or -18?

a little help, please?

HeyMister -

I just tried this with parts found at various local hardware and DIY stores, and it didn't work so well. I went to McMaster-Carr, and ordered some parts to demo so that I could build some inexpensive water toys for my toddler's preschool, and I think I've found a winner. Here are the specs, and part numbers in case anyone wants to try it.

O-Ring (Silicone, FDA grade, since kids might drink the water): #317 (PN: 9396K288)

1" Female Slip to 3/4" Male NPT Thread adapter (PN: 4880K434)

3/4" Pipe Coupling (If you use a coupling, you don't even need to drill for the pin, since it has a stepped part in the center that is smaller than the ball) (PN: 4880K72)

White Delrin FDA grade ball 1" (PN: 9614K27)

With these part numbers you could build ten valves for about $3.50 each. Only issue could be that the coupling is not a press fit inside the 1" slip adapter - there is a slight gap. You could boil the coupling and flare the end a bit if you needed to, otherwise, the glue might actually fill the gap. For high pressure, though, I wouldn't trust that.

gattlinggun1 month ago
Will a marble work instead of the acrylic ball
Tex Arcana2 months ago
I agree with curtlezumi: PVC is too frangible for compressed air, but brass or iron pipe can do the same job, just cost more. otherwise, awesome as usual
Fixitmyway4 months ago
Where did you find the acrylic balls at? The ones I found so far are a tad expensive for making these. Thanks!
jbpitcher7 months ago
Why do you have to cut the top off of the bouncy ball? Won't it turn during use and become displaced? Thanks
poofrabbit7 months ago
Hey congratulations on being a finalist in the weekend projects contest!
mr fat8 months ago
Awesome valves!
gunboatbay8 months ago
Very handy. I used the roller ball from my spouse's travel-size roll-on deodorant for the ball.
curtlezumi8 months ago
This is a great Instructable.

Avoid using PVC for compressed air. Pressurized llquids are OK. If you have a compressed gas and the PVC breaks, it can send shards of the tube flying at high speed.

For low air pressure applications like the balloon check valve it's great. For higher pressure limit yourself to liquids.
profpat8 months ago
nice instructable, i plan to build one made of metal for my air compressor external tank! have been thinking of using steel ball bearing and o-rings inside a copper tubing with /8 straight adapter on both sides..
thumpik8 months ago
I bet your brain is in overdrive all the time. This was a really cool idea you came up with. All I need is an application to put it to use. Good Job!
woodNfish8 months ago
Help! My little bouncy ball is round and I can't find the top!
Wazzupdoc8 months ago
Oh Magoo! You've done it again! Terrific I'ble.
HOWITZER8 months ago
Amazing!!!, now let's make some transistors XD!
MikB9 months ago
Another option for a ball style check-valve: An old (wired) mouse ball. These are usually pretty weighty, and have a rubbery coating that makes a good seal against a metal bearer surface.

In my case, I used a spacer ring from an old 3.5" hard drive, which had a nicely ground bevel on the inner edge. Gravity (and back pressure) holds the ball firmly into it, a cross-wire above the ball stops it getting pumped clean out :) The ring JUST fits inside a 32mm waste pipe.

Just watch out for using these outdoors, when the check valve keeps water inside it and it freezes, it can force the ball to stick!
Mouse "balls" (Oh I remember them) are steel balls with a rubber coating on them...

Completely clueless about them being used for anything except mice tracking, but I think they would be fine for situations where the seating pressure / area was proportional to the force, and I am not sure about the fidelity of the rubber coating, as it was made for a dry rolling environment, and the coating on the steel ball, may only be good for that, and not sustained immersion in wet and or high mineral content environments waters.

But then again - the mouse balls may in fact be check valve balls repurposed - who knows? - and life goes on.
Hoopajoo9 months ago
Where did you find the acrylic/plastic ball? The only ones I can find here that would fit are made hollow from hard & brittle plastic. Any help is appreciated. I'm thinking of planting my rain collection cisterns underground to keep cool, reduce light and therefore algae formation. The pump you demonstrated would fit the bill perfectly for getting water from underground cisterns for watering plants.
Probably the same type I've ordered from Industrial Plastics in the past, here's a link to their 3/4" bag: http://www.industrialplasticsnyconline.com/ProductDetails.asp?ProductCode=Acrylic+Balls+3%2F4+inch
clazman9 months ago
Very nice. I like ideas that develop into something useful. Had I needed one I probably would have come with.

My only complaint is that you didn't quite go far enough. I would have designed it so that the couplings would have came into contact with each other removing the need to have to pay particular and needless attention during final assembly. This would only require taking careful measurements of all of the components.

It is for that reason that I cannot vote for it.

Anyway, a fairly decent design.

It;s surprising how a video is very impressive for an incomplete design. But, that is the world of marketing.
clazman9 months ago
Very nice. I like ideas that develop into something useful. Had I needed one I probably would have come with.

My only complaint is that you didn't quite go far enough. I would have designed it so that the couplings would have came into contact with each other removing the need to have to pay particular and needless attention during final assembly. This would only require taking careful measurements of all of the components.

It is for that reason that I cannot vote for it. A job incomplete.

Anyway, a fairly decent design.
Very good idea, easy to do at home conditions and as you can see in the video effectively.
cybercapri9 months ago
This is a great one way check valve, thanks for sharing....
downeasta9 months ago
Why flatten the bouncy ball? Couldn't the flat rotate and cause problems?
billbillt9 months ago
great
Macflame9 months ago
Top job once again!
SussoGobbino9 months ago
Really nice and useful!
SIRJAMES099 months ago
you always seem to have the coolest projects!!
this is no exception either! 8=)
TY for sharing Sir.
Nice idea. Check out the one I made out of brass fittings.
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