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2.5" piston valve help
Posted: Wed Mar 25, 2009 5:45 pm
by LCTChamp
Well my 2" sprinkler valve on the 2SVGBG ( the gun is here
http://www.spudfiles.com/forums/finnaly ... 17632.html) quit working and I haven't built a piston valve yet. So I decided to build a 2 1/2" piston with 2" porting. My hardware store had 2.5" sch. 40 conduit fittings. Can 2.5" conduit be safely used with 100 psi? If not I will order the appropriate fittings online. I noticed 2" pipe fits reasonably well and only needs a few wraps of tape to fit well. Can a piston made with 2" pipe seal well against a 2" barrel? Would the piston be safe if I filled it with hot glue or do I need to fill it with epoxy?
Thanks for any help in advance.
Posted: Wed Mar 25, 2009 5:58 pm
by jmeyer1022
I believe the conduit will be fine, I'm not positive though, in my 2" cannon I use a 1 1/4 coupling as a piston and it seals against a 1 1/4" coupling so you should be ok there. Filling the pip with epoxy/hot glue a little would be a bad idea, doing the whole thing would have to much mass.
What I did was:
I used "welder" its an epoxy, to hold the washers to the piston better and seal so nothing got inside. It hold's great.
Posted: Wed Mar 25, 2009 6:05 pm
by LCTChamp
Thank you! I will use your idea. Anyone know for sure if I can use conduit with 100psi?
Posted: Wed Mar 25, 2009 8:37 pm
by mark.f
I want to say that conduit is cellular core, but you should check that. If it is, then it would be a mistake to use it in a pneumatic.
2" porting is a little more confusing than using 1-1/2" or below in a 2" tee, or 3" in a 4" tee, because there are not a lot of things that fit into 3" pipe. 2" SCH-80 fittings fit well, but not well enough.
I say try using a 3" tee instead of the 2.5" one, though.
Posted: Wed Mar 25, 2009 8:40 pm
by Carlman
mark.f wrote:I want to say that conduit is cellular core, but you should check that. If it is, then it would be a mistake to use it in a pneumatic.
as did I but wasnt sure
Posted: Wed Mar 25, 2009 9:19 pm
by jrrdw
The problem with your plan is you wont have any surface area on the outside of the barrel for the air to push the piston back. It still might work but the performance will be bad.
Posted: Thu Mar 26, 2009 6:04 am
by LCTChamp
The problem with your plan is you wont have any surface area on the outside of the barrel for the air to push the piston back. It still might work but the performance will be bad.
That is what I was afraid of. Well I guess I'll have to order fittings online. Back to the drawing board!