Compression spring for barrel sealing

[randomvictim]

Where do you get your springs for barrel sealing valves? How strong should it be? I am building my first tomorrow and need as much information as possible. I am not going to use the spring out of a sprinkler valve, because then I would have to buy another sprinkler valve and 15 bucks for a spring isn't going to work out .

[Zorrowannabe9]

well springs arnt that hard to come buy. You can find them at OSH, probably Home Depot, and I'm sure that theyre available in countless online stores. As far as how strong they should be? Not terribly, just enough to make the piston return to sealing the barrel when the pressure from the chamber has equalized. Also, you dont NEED a spring, its just nice to have, helps in the sealing process.

[userjjb]

Barrel sealing valves don't need a spring to seal the piston as long as you fill from the pilot side. If you fill from the chamber however, you will need one. IMO it'd be far easier to just fill from the pilot, the fewer the parts to break the better.

If you still want springs, check out a hardware store (Ace, Lowe's, etc.), they will usually have a whole bunch in various gauges. The spring doesn't need to be exceedingly strong, just strong enough to overcome the friction of the piston sliding. If the spring is too strong, I imagine it would adversely affect your valve opening time though.

[randomvictim]

I do intend to fill from the pilot side so I guess I am good. I am going to make the piston out of hot glue and not quite sure what I am going to use for the sealing face but I am sure I have something laying around that will work. I also plan for my barrel to be half inch, what size tee should I use? The bigger the better i would assume.

If I don't use a spring do I need a bumper? I don't want a broken piston .

I also don't understand how air is supposed to get past the piston of I don't make an equalization hole, and if I do, how big to make it. In the barrel sealing video tutorial he doesn't make an equalization hole.

[Zorrowannabe9]

Most kinda of rubber will work for a sealing face. An old bike tire would probably work!

yes you need a bumper or you will shatter the pipe.

Air will go around your piston unless you use o-rings on the outside of it to make it airtight.

[randomvictim]

I don't know what to use for a bumper. I don't have any spare tennis balls or garden hoses laying around. Any suggestions?