question on diaphram in a "Supah valve" design
Posted: Sun Nov 26, 2006 1:40 am
I am new to this forum and need your help. I have build combustion guns before but am building my first air cannon. It has a 48 inch by 4 inch chamber and has a 72 inch by 2 inch barrel. All parts are PSI rated schedule 40 PVC. I am using a diaphram valve design found at he following link; www.geocities.com/advancedinventions/plansspv.htm
the chnages I have made is that rather than using the 1/8 inch hose fitting I have plumbed in 1 inch pipe back to a one inch modded sprikner valve that will be activated with a blow gun. I am using 1/8 inch rubber for the diaphram from a mud flap. It has a 2 3/4 aluminum disc on the back side. My question is the positoning of the barrel outlet to the diaphram. Once the glue sets there will be no moving it! I believe that this is how to postion the barrel outlet; I am guessing there needs to be enough spring pressure againest the diaphram at rest that it seats againest the barrel so it needs to be bowed out slightly and againest the barrel. When I activate the spinkler valve the change is pressure will pull the diaphram back away from the barrel and the air will shoot up the barrel outlet. Am I right? Other than postioning the barrel outlet and picking the spring the cannon will be ready. Because of the 1 inch outlet behind the diaphram I have to find a spring a little over an inch in diameter and as of yet have not found one. Any advice or comments will be apreciated, this site/forum has already answered alot of questions for me.
the chnages I have made is that rather than using the 1/8 inch hose fitting I have plumbed in 1 inch pipe back to a one inch modded sprikner valve that will be activated with a blow gun. I am using 1/8 inch rubber for the diaphram from a mud flap. It has a 2 3/4 aluminum disc on the back side. My question is the positoning of the barrel outlet to the diaphram. Once the glue sets there will be no moving it! I believe that this is how to postion the barrel outlet; I am guessing there needs to be enough spring pressure againest the diaphram at rest that it seats againest the barrel so it needs to be bowed out slightly and againest the barrel. When I activate the spinkler valve the change is pressure will pull the diaphram back away from the barrel and the air will shoot up the barrel outlet. Am I right? Other than postioning the barrel outlet and picking the spring the cannon will be ready. Because of the 1 inch outlet behind the diaphram I have to find a spring a little over an inch in diameter and as of yet have not found one. Any advice or comments will be apreciated, this site/forum has already answered alot of questions for me.