[MrForbes]

Matt looked into using ball valves, and could not find any that would work with the pneumatic cylinders we had available. They have too much friction, for one thing.

Weight of the complete valve assembly is actually relatively low, although I don't have a number and it's all assembled now so I can't weigh it. You can visit a hardware store and look over the valves, and see how the weight compares between gate valves and ball valves, if you'd like.