Note there is a difference in the older crusher pressures & PSI. That 3 Ton pressure was crusher. Converted to present day PSI as recorded by a Piezo-electric crystal it is very near 9,000 PSI.
Excellent point, and one we often overlook. And that's service pressure, not proof pressure--even though you'll see some British references to "3 tons proof". The Brits, as of 2005, have now dropped all marks that reference a specific pressure, such as 3 tons or 850 bar. It's now either STD under a crown (for standard, which replaces the old 850 bar) or SUP under two crowns (for superior, which replaces the old 1200 bar). But all those specific pressure references were crusher values, not piezo-electric. Which means, for example, that you cannot multiply 850 bar x 14.5 to get the proof pressure in psi. Per the Birmingham Proofhouse, "standard"/850 bar proof works out to 13,920 psi.
Last edited by L. Brown; 05/13/13 08:35 AM.
