Re: cartridges and pressures

20 December 2004, 12:18

Hot Core

Quote:

... ALF is correct, the difference between CUP and PSI varies from one cartridge to the next, in a very unpredictable way. For example, in the .45/70, C.U.P. and PSI are equal!!

If anyone ever mentions that I "agreed" with eldeguello, I'd certainly not appreciate it. That said, he is totally correct in that there is no accurate conversion between CUP and PSI.

Quite a few years ago I wondered if there wasn't some formula that could be used to do that conversion myself. Messed with the numbers as something "fun to do" while running some other time consuming tests and decided it could be "misleading" because the conversions just won't work in all examples.

Went so far as to make a couple of calls to folks who I knew would have the scoop. Also asked them "why" no conversion factor or formula was shown in any of their latest Publications or Manuals? I was answered very politely but in no uncertain terms that though considerable effort had gone into attempting a conversion, none they had tried worked correctly 100% of the time.

Have no desire to debate the issue. Call the folks who write the Manuals and you can verify it for yourself. Meanwhile, try not to blow yourselves up.

20 December 2004, 12:37

denton

Or, call the people who write the European manuals, and ask them why they do this in all cases. If it works for CIP, why would it not work for SAAMI?

Or, if you prefer, consult one of the most comprehensive studies of pressure factors ever done, Dr. Lloyd Brownell's work in the physics department at University of Michigan. On page 30, you'll see Figure 8, and on page 35 you'll see Figure 14. They show how to convert PSI to CUP, and back.

18 December 2004, 17:20

cummins cowboy

what if steel is used?? also what is the difference between cup and PSI