SpudFiles

120psi for a 3000cu in chamber is a lot

If you saw the book, you may have noticed I did not include any pressure ratings in there. This is because it is not rated for air and I don't want someone to try and blame me for blowing their right hand off by filling it up to a pressure I quoted.

so air pressure is "stronger" then water pressure?

The only thing that matters with water and air pressure is when the pressure chamber fails. If it doesn't fail, there's no difference.

If it does fail, pressurized air will transfer more energy to the shrapnel, meaning the shrapnel travels faster and makes it more dangerous. Because water is heavier, less energy is transferred to the shrapnel so it is a lot safer.

Finally some one managed to explain that in a way i could comprehend, thanks alot Mr.C

is 1" the biggest sprinkler valve you can get? (I know it is the biggest I have found, I am just curious to find out)

I've seen them up to two inches. They tend to be expensive, though.

what is the common size which you would recomend?

1" is the most common among spudders. I'd recommend it over a 3/4" one.

I've seen sprinklers up to 3", though like hubb said they get very expensive.

That depends on what you are trying to do, but, for most applications here, a 1" inline seems to work fine, especially after modding the 'phragm and blowgun.

Ok thank you for your help

I have used mine up to 220 psi before with no problems. I tried to mod the diaghram on mine but failed. I am still trying to get it figured it out so I can build a large bore cannon, but I will probably just use two valves.

FYI

I haven't forgotten about this. Just been really busy lately, with Christmas and all.

Anyway, I have added a few things to this:
- I have added more detail on an anti-siphon sprinkler valve
- I've added much more detail to the sections, including photos
- I've been working on another method for advanced modification. When it's successful, I'll add it.

So what kind of advanced mods are you going to try.

john bunsenburner: "so air pressure is "stronger" then water pressure?"

MrCrowley: "Because water is heavier, less energy is transferred to the shrapnel so it is a lot safer."

Wouldn't it have more to do with the fact that water/liquids are basically incompressible, meaning, when the pressure is released (due to failure) they do not expand further. While with air and other gasses being compressible, when a failure occurs, all that pressure is released in the form of rapid expansion. Kind of like a compressed spring.

Ah yes that's it!