I've always wondered about the 3 tons/850 bars thing. During the late 80's, both those marks were still being used by the proofhouse, but I THINK (although am not positive) that the proof pressure was the same. And I know that the 10,730 psi service pressure figure (piezo) for 850 bar guns is correct. That one is straight from the Birmingham Proof House. Which causes me to wonder whether the 8900 psi service pressure figure for the 3 ton guns might not be a crusher number rather than piezo. Using the LUP = 1,000 = psi, which is only a ballpark guesstimate, 8900 sounds too low. But I don't believe they changed the proof and service pressure standards when they went from the old tons system to the new bars --although again, I may be wrong.
