Leaking sprinker valve?

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Postby randomvictim » Mon Dec 18, 2006 11:30 am

Yesterday I modified my first sprinkler valve. I took the top off and drilled a hole threw the lid, tapped it, then screwed in a 1/2 " nipple to which I attached my blow gun.

If I blow in one side of it, it comes out the other side. If I fill up my gun the valve leaks all my air, making a rather annoying noise. I screwed a PSI gauge at the other end of my blow gun to see if it was doing anything, no pressure builds up when I open up the blow gun.

What could possibly be wrong?
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Postby Mr.Plow » Mon Dec 18, 2006 11:36 am

Open the valve up and clean any debris from the sealing face. If you removed the spring from the top of the valve, replace it. Of course be sure there is no leak around the nipple, and finally if none of the previous worked then you may have to remove any obstruction from the equalization hole in the diaphragm (usually there is a small piece of plastic in it)
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Postby randomvictim » Mon Dec 18, 2006 11:46 am

There was some plastic debris from the making of the plastic casing around the sealing face and I just removed it with a Xacto knife. I am holding the spring down all the way until it is compressed, pressing against the back of the sealing face, and it isn't being pressed down hard enough to stop air from flowing. Am I supposed to pressurize the space between the blowgun and sealing face with my compressor manually or something?
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Postby An Apple Pie » Mon Dec 18, 2006 11:57 am

No that space is filled through a little hole in the diaphram. Did you try taking the diaphram out and removing the little white plastic piece just barely hanging on to the diaphram. The piece of plastic has a lot of little holes, and you can just pull it out. That is what fixed mine.
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Postby Navigator7 » Mon Dec 18, 2006 12:06 pm

A half inch nipple?
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Postby randomvictim » Mon Dec 18, 2006 12:21 pm

I just removed the little white plastic piece by the diaphragm, still no help.

Yes, it uses a half inch nipple to screw in to the blowgun. Did I do the wrong end or something?

Edit: It works now. I don't know what changed, but it works.
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Postby Navigator7 » Mon Dec 18, 2006 5:16 pm

I dunno what size sprinkler you are using...but the sprinklers around here you can only tap for 1/4" npt and there ain't a lot meat for goofing up.

A blow gun take 1/2 NPT? Where you from, Texas?
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Postby randomvictim » Mon Dec 18, 2006 6:48 pm

In diameter, not radius, so technically 1/4 NPT. My drill bit (measured in diameter) was 1/2.

I got it all put together now and it has a really nice crack to it. It leaks a little around where the nipple attaches to the lid but I'll JB weld that up.

For some reason I always get two shots out of my gun, the second is weak and makes a low hum instead of a crack.
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Postby Navigator7 » Mon Dec 18, 2006 7:38 pm

<blockquote id="quote"><font size="1" face="tahoma,verdana,arial" id="quote">quote:<hr height="1" noshade id="quote">Originally posted by randomvictim
[br]In diameter, not radius, so technically 1/4 NPT. My drill bit (measured in diameter) was 1/2.

I got it all put together now and it has a really nice crack to it. It leaks a little around where the nipple attaches to the lid but I'll JB weld that up.

For some reason I always get two shots out of my gun, the second is weak and makes a low hum instead of a crack.
<hr height="1" noshade id="quote"></blockquote id="quote"></font id="quote">

Oooops...EDIT: Leaking around the top of the sprinkler, a leaky blow gun, leaky hose to the blow gun, a dropped blow gun, wrong hose and fittings on the blow gun or whatever valve you are using to fire.....is just like a loaded gun with a kid's finger on the trigger. The absence of pressure on one side of a diaphragm is just like pulling the trigger on a gun....no matter the reason. Less air? Fire!

Ok...get a handle on fitting sizes or you are gonna look dumber than you really are.
(Which is better than being dumber than you look)
Learn fitting sizes...or at least know where to go to find out fitting sizes.
There are not too many fitting sizes. (1/8; 1/4, 1/2, 3/4 and 1") Hydraulics has a
5/8" size.)

BTW...I'm not calling you dumb. Fidgety is dumb.

Drill properly.
Drilling 1/4 npt with a 1/2" drill bit is not proper and explains the leak.
Way too big a hole.
I think it takes a "27/64" drill...drilled properly with no shake. IE...the part clamped securely, the drill tightly chucked and an appropriate chip taken at the proper drill speed when doing the drilling. Proper speed? Fast rpm and slow feed.
Holding the part with your feet, using a slow speed drill motor with a deming drill going through plastic and a few beers...mandates going down a few drill sizes or ordering a few more sprinklers.

The two shots from your cannon means your exhaust valve is being activated twice.
Duh.
It the same physics that makes your valve work in the first place.

Personally...I think your "1/2 pipe nipple"...which is really 1/4 nipple is screwed in so far into the sprinkler lid the diaphragm hits the nipple. (Because you used the wrong drill bitt) The diaphragm has a few choices...either stay open or close down. So ...it closes but your hand is still on the trigger so it fires again. Either way I think you are giving up power.

Also....is your blow gun on the valve or attached to a hose?

Try a heavier projectile or try grinding the thread off the nipple protruding into the area the diaphragm is trying to occupy. Did you epoxy it yet?

Fun stuff despite it doesn't come out of a box,eh?
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Postby randomvictim » Mon Dec 18, 2006 10:45 pm

I unscrewed the nipple some so as not to hit the diaphragm, and JB welded around it to stop the leak. Hopefully tomorrow when it is dried all the problems will be solved.

For the record, I have another gun with very similar chamber and barrel sizes that uses a ball valve. Opening the ball valve as fast as possible results in a hiss. The sprinkler valve provides a very loud crack which is most satisfying.

To anyone using ball valves I strongly recommend switching over to sprinkler valves.
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