By hg, I assume you mean mm of mercury (Hg). If so then 10 mm of mercury is about 0.193 PSI, so no they would not cancel out and the valve would stay shut. If you wanted the direct opposite for PSI it would be Torr, so 10 PSI applied to one side of the valve and 517.1 Torr pulling it down, would equal out to zero.
Thanks Symon, but by in hg, I was referring to inches of mercury. Probably should have put inHg shouldn't I,
An inch of mercury is ~ .491 psi, you would need just over 20" of mercury to balance the 10 psi
Thanks Garfish, that's exactly what I was after.
That'll hopefully help me understand what's going on with a fuel pressure regulator I'm having some trouble with.
Thanks guys,
(Next problem. Don't suppose you guys have any experience with boost referenced fuel pressure regulators on twin turbo big blocks with a blow through set up do you
)