Been a while

Mike_Hunt0420 · Mon Oct 12, 2009 9:06 pm

I haven't posted in a while and I doubt I'll manage to finish before the deadline for the power contest but if I could get a little advice I might be able to pull it off... I'm finishing up my high pressure piston and I'm at a loss for a trigger for the 800+ psi. Any ideas? Hammer valve or something? I'm frazzled.

maverik94 · Mon Oct 12, 2009 9:09 pm

Pushbutton valve maybe? There are a few around on sf.

jmadden91 · Mon Oct 12, 2009 9:32 pm

The power contest specifies that the chamber must be made of PVC or ABS only. So any 800psi piston cannon is out of the question anyway mate.

Still sounds good though, Good Luck

Reactor4 · Mon Oct 12, 2009 9:45 pm

Wellll, actually, the max op. pressure for sch. 40 pvc is about 350. BUT, that is where ASTM rates it for safe use, if you wanted to risk it, you could refer to the bursting pressure which is appx. 1700-1800 psi. sch. 80 is obviously higher. But please don't interpret this the wrong way, im simply putting the info on the table, one may take it as one wishes. (and abs, would be a death sentence to use, so don't use it.)

Source : engineeringtoolbox.com

Reactor4 · Mon Oct 12, 2009 9:48 pm

oh, i must add that bursting pressure varies inversely with pipe size. and the warmer it is, the lower the pressure rating, since PVC is in fact a thermoplastic.

Mike_Hunt0420 · Mon Oct 12, 2009 10:24 pm

Then I guess I wont enter the contest, I was HIGH pressure so I'm going with seamless steel fittings. thanks for pointers.

Crna Legija · Mon Oct 12, 2009 10:34 pm

You could use a pressure washer
http://www.pressuretek.com/test.html

there rated to 2000-4500 psi

Mike_Hunt0420 · Mon Oct 12, 2009 11:11 pm

They'll work? I wasn't sure if they'd function properly or not. I know they can take the pressure but wasn't quite certain it would work properly.

theBOOM · Tue Oct 13, 2009 3:13 pm

Who says you cant use pvc? you could simply order a 3 inch pvc rod

twizi · Tue Oct 13, 2009 3:29 pm

the presure washer handle have worse flow then blow gun

Hubb · Tue Oct 13, 2009 3:32 pm

twizi wrote:the presure washer handle have worse flow then blow gun

But are ideal in a high pressure setup to dump pilot air. Remember, if the piston is built right (and I hope it would be if the builder plans on using 800+ psi), a small break in the pressure, which is what a pressure washer handle will cause, will do the job.

twizi · Tue Oct 13, 2009 4:25 pm

very true

Technician1002 · Tue Oct 13, 2009 7:39 pm

jmadden91 wrote:The power contest specifies that the chamber must be made of PVC or ABS only. So any 800psi piston cannon is out of the question anyway mate.

Still sounds good though, Good Luck

Maybe..

Think of a way to keep the pressure differential between each layer of the launcher under 150 PSI per layer.

In one of my old posts on the subject I mentioned how to go to 500 PSI in PVC. A fair amount of custom fitting mods is required as well as an extensive network of stacked regulators and cascaded check valves, but it can be done. The usual disclaimer that it is unsafe applies.

Mike_Hunt0420 · Wed Oct 14, 2009 12:41 am

as always thanks for all the pointers, I'll get to work on finishing the beast up and let you guys know how everything worked.