Okaydoke. Here is today's valuable learning experience:
Don't use a valve like this in the 1.5" size (I've used similar half-union'd valves on 1", 3/4" and 1/2" without issue on a few calcium reactors I tried making back in the early days).
The 3 little sticks are these little holder things that keep in place the white plastic ring that in turn holds the ball in place. The ball just sits in the fluid and it's insane how loose it all is (it just falls out when you take the clip out). There's no way this thing could hold back pressure of any kind ... and, well, it didn't. 10" of water and the thing was leaking right through the join. In fact I can blow into the pipe and the air escapes out - not through the ball - ie., water wouldn't flow through the pipe at least, but the housing isn't watertight in the least.
I can't imagine ANY scenario that a valve like this would be useful. What the heck???
Off to find me a true-union 1.5" valve tomorrow. Man I hope Red Coral has one in their boxes-o-plumbing heaven .. to order something like this from BRS is do-able but darn it all if that isn't another 2 weeks or whatever. I suppose I could just use a standard PVC valve from HD and a union and get the same effect but that will end up being huuuuuuuge and cumbersome and I'd just rather not.
Bah!
Guess it's still better to find these things out now and not after there's rock and sand and livestock in there.