gate valve shopping

[sharuq1]

I googled gate valves and it seems there are options I of course knew nothing about, like what lubricant is in it. Can I safely use any of these on my tank? And if so which one would you recommend? (size/type/etc.) If not I know OA and JL have them, is there anywhere else that has them? I don't want to buy from the sites I listed, they are just a reference for the gazillion types there seem to be.

Also what is the point in a "thread x thread" valve that makes it more expensive than a normal one? Am I better off buying a threaded valve or just getting a non-threaded and glueing everything?


http://www.coleparmer.ca/catalog/pro....asp?cls=26692
http://www.usplastic.com/catalog/pro...ookie%5Ftest=1