The Sprinkler Valve (PDF File)

[Hubb]

Okay so this is probably a dumb qeustion but the diaghram have to be perfectly round?

If you are referring to the diaphragm already available, they are already round. If you are referring to the homemade mod, the straighter it is, the better (make it perfectly straight).

Which valve is best? I read that rain bird is good because the cap is thicker and better for threading but which valve is quicker to open?

IMHO, an Orbit Watermaster is the best one to use (it's the one for sell on the main page of this forum by BC Arms). It has a fairly thick, flat top, and does not have a guide rod to deal with. I've never had to use epoxy after tapping into one of these, however, I did have to on the Rainbird (with guide rod).

[Hubb]

Just a note: I have Wikied this. The wiki just shows what is in each section and also provides the link to download the book.

The wiki article can be found here. Please let me know if it needs to be changed or formatted or whatever.

Thanks.

[Atrocity]

can one use a 3/4 valve? will there be a big difference in power compared to 1 inch valve?

[JohnnyBOOM]

The difference between the performance of the two valves can be estimated by the difference between the cross sectional areas.

csa for 1" --> .7854" sq
csa for .75" --> .4418" sq

So you will have ~ .4418/.7854=56.2% less "power", if the valves are feeding identical barrels and ammo.

[dewey-1]

you will have ~ .4418/.7854=56.2% less "power", if the valves are feeding identical barrels and ammo.

Actually it is not 56.2% less power, but rather 56.2% of the 1" Valve.
That equates to 43.8% less power.

I know it sounds like nitpicking.
You had the right idea though.

[Atrocity]

wow thats alot, damn i already started on mine..

[psycix]

Not less "power"
Less FLOW.
But on low velocities and small diameter barrels (compared to the valve) it doesnt matter much.

[JohnnyBOOM]

Actually it is not 56.2% less power, but rather 56.2% of the 1" Valve.
That equates to 43.8% less power.

Lysdexia Strikes Again!

[c11man]

hey i looking at doing the piston mod and was wondering if anyone else has done it?

of course hubb has...

[Hubb]

As far as I know, I have been the only one to do this. If it has been done, it has not been brought to my attention. I was inspired by noname (I wonder what ever happened to him anyway), which did the first diaphragm replacement that I know of here, which is also covered in this book.

Please note that I have done this only once, but it is a definite upgrade I'll be doing to any other sprinkler valve launchers I build. As with any piston valve, anything can be used for a piston, as long as it fits. I made pvc sheet from 2" Sch40, which seemed to be just right. Also, I used metal hardware but I believe in the book I recommend nylon hardware, as this will cut down the weight.

Was there anything in particular you want to know about it?

[c11man]

so if i under stand this right a sprinkler converted to a piston without a spring will have to be filled from the vent right?

i dont have any 2in pipe but i do have some 3inch laying around. will this increase piston weight too much?

when you say to use nylon hardware i dont get what you can replace. the bolt and nut have to be metal so i dont know what to use nylon on.

also i was to vent this from a distance. i have a 6ft 3/8 hose that the barbs go to 1/4inch threads. i will be using a 3/4inch ball vavle (just had one laying around) will the hose be too long and increase piolet volume too much?

[Hubb]

- Yes, just like a conventional piston. This will allow the piston to seat on the exhaust port.

- 3" pipe should work, or you could try wood or any other material you have handy

- Most hardware stores carry nylon nuts and bolts. They run around the same price, but are so much lighter. They are white.

- I've always used 1/4" hose to relocate my trigger on a sprinkler valve launcher, but I've never used 6ft of it. It may be a bit too much.

[Carlman]

if you want 6ft relocation then mod the valve with an unmodded valve then use electrics

[c11man]

i never noticed the nylon bolts and nuts.....

i can make the hose shorter i just had a 6ft one laying around.

how long do you think i can have it? (i REALY dont want to stand RIGHT next to my cannon when i fire it)

also have you ever considered a check valve in a piston conversion?
probably a crazy idea but oh well

[Hubb]

Actually, the book coveres a check valve in the piston config.

And I am considereing remaking the piston to better suit the check valve, to make it more efficient and increase the power, although I don't really know how much more power I can get from one.

As far as the hose, mine are usually no longer than a foot, depending on how it's set up.