I assume that DIR doesnt like inverts?
Reasons are? I ask because to me inverted seems much more logical/practical. Access to valves is much easier therefore shutdowns are a doddle. I should add that I do not do overhead environments and have managed in the past to hook my single tank up in the shot line, so a pair of valves would seem to be really asking for trouble (in my case

anyway, so far.)
But what are the factors that preclude inverts, I wont use the term wrong-way-up?
Given that inverts are used by some, does the LHP/RHP split still stay the same.
Matt