I recently purchased 14 2" true union ball valves.
For the sake of simplifying this discussion, lets refer to the inlet side of the valve as the side where water flows into the valve form a source, such as a pump, filter, gravity, etc. The outlet will be the side of the valve that water flows out of the valve back to the pond.
I always assumed when installing true union valves, you want the adjustable block on the outlet side.. so if you need to adjust it, you can close the valve, and remove the outlet side to adjust the block (assuming you can move the outlet pipe). This would mainly be in the case of gravity flow.. for instance on a bottom drain line. You cannot remove the valve completely to adjust it because your pond would drain out, but you can close the valve and remove the outlet side to adjust it, and it would still hold the pond water in.
Well, the new valves I bought have a arrow to indicate the direction of flow, and they indicate the water should flow in the side of the valve where you would adjust the block, essentially making it impossible to adjust if there is any water or pressure behind it.
Is this backwards... or does the direction flow arrow on the valve really not important, and am I correct above in assuming how they should be installed?
Thanks in advance for the help