Homemade Check-Valves - Clean, cheap and effective

Guides and discussions about building water blasters and other water warfare devices such as water balloon launchers.
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WaterWolf
Posts: 448
Joined: Sat Jul 08, 2006 5:13 pm
Location: Central Vermont.

Post by WaterWolf » Thu Aug 09, 2007 1:11 pm

What is the single most expensive piece on most APHs? The answer will usually be, the check-valves. These simple devices run at prices around $10 each and since APHs will often require two of these, almost half the money spend on a homemade might end up going into its check-valves.

In an effort to make homemade soakers more affordable in general, I have designed a very simple but effective check-valve, that can be built at home for the amazingly low cost of $3.60 each and takes only five easy steps to build.
These instruction will show you exactly how to build a 1/2-inch check-valve. You can vary the sizes of material for different diameter pipes.

The design and operation of it are basically the same as their store bought brethren. A short tube with a reducer at each end, a cone of rubber pressing on one of the ends from the inside and a spring that is pushing on the rubber.
The only parts you need are:

A 2-inch long section of 3/4-inch PVC.

A 3/4 x 2 - 3/16 x .062 compression spring.
I got those numbers off the box of springs. I believe that the first two indicate width and length in inches. The second to last number is how thick the metal is and the last one is the pressure it exerts. These numbers should allow you to find the exact spring, but if you cant, just try to find a compression spring that fits well into a 3/4-inch pipe and is not too long.

A 1 1/4-inch "CampBell Hausfeld" bike-tire valve.
These are easily identifiable by a cone-shaped rubber gasket. The rubber is the part you really need here. If you can find another cone-shaped piece of rubber however, it may work just as well, but these seem to be perfect for my purposes.

And two, 3/4-Inch female-smooth to 1/2-inch male-threaded couplers.

Image

1: Following the instructions on the can, PVC Cement one of the couplers onto an end of the PVC pipe. Let this dry.
2: Insert the neck of the tire-valve into one of the ends of the spring.

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3: Slide this tire-valve and spring assembly down the pipe. The end of the spring should protrude about a half inch out of the PVC.

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4: Glue the second coupler onto the other end of the PVC to close it up. Remember hold the coupler pressed onto the PVC pipe with your hands for about 30 seconds, so that they do not pop apart.

You have now built a fully functioning check-valve in only a few minutes and saved about $6.40 on your next project requiring one of these.

Image

I have not actually used these in a homemade yet, but I did run some pressure tests and found that they worked beautifully.
The Maple-Mountain-Marines.

Terrifying, but oddly refreshing.
-B.D.

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isoaker
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Post by isoaker » Thu Aug 09, 2007 1:19 pm

Very nice! Great pics, too! How much, if any, backflow do you notice when you attempt to pump water against the direction it opens? Also, how smoothly does water appear to flow through the valve when water is being pushed in the correct direction?

:cool:
:: Leave NO one dry! :: iSoaker.com .:

DX
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Post by DX » Thu Aug 09, 2007 1:22 pm

Very nice, very clean. But $10 for a normal 1/2" check valve? You're getting ripped badly! My Lowes carries 1/2" ones for $5.35 and 3/4" for $5.85. :p

Some questions -

Can that be done without using threaded couplers? Two more female 1/2" would be needed, and that makes the overall valve rather long [and price closer to the normal valves]. Actually, I think I have a 1/2" to 3/4" plain reducer, I'll have to go look.

How well does the rubber valve thing hold the kind of pressures built up in a typical APH? Also, where might those be found?
marauder wrote:You have to explain things in terms that kids will understand, like videogames^ That's how I got Sam to stop using piston pumpers

WaterWolf
Posts: 448
Joined: Sat Jul 08, 2006 5:13 pm
Location: Central Vermont.

Post by WaterWolf » Thu Aug 09, 2007 1:39 pm

@DX:
I buy the Bike-Tire Valves at my local Wal-Mart in the bike-section.
You could give the valve smooth connectors instead, but it will need to reduce in diameter a certain amount to allow the rubber to block the end.

@ISoaker:
There is no noticeable back-flow when I pressurize in that direction.
The tests I did actually used air instead of water, but when I send it through the "In" side, it does make a sort of "ThupThupThupThup" sound, like the rubber is opening and closing really fast while its flowing.
However, I'm using a stronger spring than is usualy found in the store-bought valves and that may be causing the problem.




Edited By WaterWolf on 1186684957
The Maple-Mountain-Marines.

Terrifying, but oddly refreshing.
-B.D.

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