I need help from a mechanical engineer. (piston seal)

[Klippymitch]

I need to make a piston seal a tube that has an inside diameter of 7/8. The piston will be taking on a pressure of around 150psi-250psi. I have an easy access to Lowe's. Is there anything I can pick up there that will allowing me to make such a piston seal?

I think maybe a nylon cylinder would work the best but I believe. They only have Nylon spacers at Lowe's and the sizes are limited such as 3/4 o.d. nylon space and 1 Inch nylon spacer. Is there a hardware store that sells nylon cylinders(not spacers) with an outside diameter a little to what I need?
What size would you recommend and what size # of o-ring?

[Facial]

I know a few things relevant to mechanics - but not too much into the nitty-gritty of hardware. What is of concern? Temperature, pressure, vibrations?

[(Q)]

I order practically everything from these guys, fast shipping, good service, if they don't have it, you don't need it. :D

http://www.mcmaster.com/

[Klippymitch]

I order practically everything from these guys, fast shipping, good service, if they don't have it, you don't need it. :D

http://www.mcmaster.com/

Thanks for the site looks good.

[scorpius]

heres some engineering forums
www.eng-tips.com