Largest Piston Valve

[Gepard]

Hi,

What's the largest piston valve ever made? We're talking about it over on UKSGC and Ragnorak (Jo's brother) said it was 3" (we're talking about the porting not the actual piston diameter) but I can't help but think it sounds a little small for the 'largest ever'....

Anyone remember a larger one?

[benstern]

I believe a 4" piston valve exists.

[DYI]

I don't know about the largest ever, but I know that 3" barrel porting is the largest that is commonly used. A piston with 4" barrel porting would have to be built in a 6" tee, which is rather impractical. It probably has been done by someone though.

[Velocity]

If we are talking tee valves, it is probably 3"... Coaxials, on the other hand, have probably been made with 4" porting.

[noname]

Anyone want to be the first to make an 6 incher? I'll give you 8" PVC for $2.50 a foot, but I'm not paying shipping on it.

[Gepard]

Hmmmm very tempted now to try and make a 4" just for bragging rights

noname,

Deal providing you pay for the fittings

[jackssmirkingrevenge]

Not strictly an amateur creation but one of these perhaps?

[Hotwired]

Mmm...

When something costs around $200,000, uses 3000psi air and chucks HE shells 5km you can be fairly sure it ain't amateur

[noname]

I have 8" PVC. That's it.

[clide]

Largest homemade valve I have seen is a 4" coaxial
http://www.spudfiles.com/forums/pumpkin-cannon-t74.html

The largest commercial valve I have seen is some 6" grain silo air cannons. They are used to clear clogs and there is also a pumpkin chunker that uses 4 of them, although I'm not sure if the pumpkin chunker uses the 6" valves, it does use this brand.
http://www.martin-eng.com/products.php?product=140