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PVC bolt in flat plug for piston valve
Posted: Sun Mar 14, 2010 1:16 am
by c11man
since spring is just around the corner i can start using my favorite spudgun material again, PVC. this cannon would be a 2inch piston but built completly out of sch 80 to allow for up to 300psi use. to keep the pilot side of the valve nice clean and small my idea is to make a flat plug out of some impact resistant pvc (off mcmaster) that fits in the pipe. it would be held in with bolts and sealed with an oring or 2. also 1/2 or 3/4in npt threads would be in the center of it. my question is how thick of pvc would i need to handle the 300psi with a saftey factor of 2~3.
Posted: Sun Mar 14, 2010 1:28 am
by spudtyrrant
well i guess its time to refer to the trusty old PVC pressure graph

it looks like 2" sch 80 should be just about suited to your needs, that is assuming this test was done with air tho, not water.
Posted: Sun Mar 14, 2010 9:50 am
by c11man
im sorry i guess the question was worded poorly. i am wondering how thick i need to make a plug that fits inside of the 2inch sch 80. the plug is flat so i know it will have to be fairly thick but beyond that i have no clue
Posted: Sun Mar 14, 2010 10:01 am
by Gippeto
c11. sheet product would have to be pretty thick to withstand the pressure....and the piston impacts, which would be pretty substantial at 300psi.
I'd use a reducer bushing...something like this;
http://www.aquariumsupplies.co.za/image ... 37-338.jpg
I'd use it something like this;
Edit: I see you know it'll need to be thick...damn wasted time searching for pictures.

Posted: Sun Mar 14, 2010 3:09 pm
by c11man
i want to avoid a actual fitting if posssible for several reasons like how the stock is going to atttach, ease of oring machining etc..... i would make the plug out of the same pvc rod that i am going to make the piston out of and it comes is 1ft sections so i will have about 8inch of the rod left over. so i can make it as thick as i want! now how think will i Need it to be?
Posted: Sun Mar 14, 2010 10:47 pm
by Gippeto
Time to do some research and learn some new math perhaps.
Have fun.
Posted: Sun Mar 14, 2010 11:32 pm
by c11man
so i did some quick looking around and a 2inch sch 80 end cap has an overal length of 2 9/32 and a socket depth of 1.5inches, simple math and some major rounding up i get 1.5 inches thick to be on the safe side. how does that sound?