Pressure question: BAR and HST?
I'm still playing with the Baikal 45.70 and before I do the next round of regulating loads I want to be sure of my pressure issues.
On the side of my barrel it says: "Warning Maximum Operating Pressure 2200 BAR Or 31900 HST"
What is "HST"?
2200 BAR = 32,340 PSI which is a lot higher than the 28,000 PSI that I was told that the limit is for this gun.
If HST is PSI then 31,900 HST would equal 2,170 BAR
28,000 PSI only equals 1904 BAR. I can't believe the Russians would make that kind of a math error. My guess is that the 28K limit was mentioned because of the availability of factory ammunition loaded to that pressure level.
Can I safely load this gun with a steady diet of 32,000 PSI loads?
14 May 2012, 14:21
Eagle OneSeveral manufacturers are using BAR nomenclature. Here are some units and conversions:
1 BAR = 100,000 N/m^2 = 100,000 Pascals (Pa).
Since F=ma, and Newton (N) is a unit of force, we get, in the metric system N = kgm/s^2.
kilogram (kg) is a unit of mass.
Now, 1 BAR = 14.5038 psi and 1 psi = 0.06894747 BAR.
Correctly, 2200 BAR = 31,908.4 psi.
I teach thermodynamics and checked for HST pressure. Not defined in any of my thermo or mechanical engineering books. But, H is enthalpy, S is entropy, and T is temperature.
Finally, a steady diet of 32,000 psi. Only 92 psi more than approx 31,908.4 psi. All manufacturers build in a factor of safety (FS) in their product. You'll never find out what it is unless you can get to the closely held proof data. All that said, what is your confidence in Baikal? Let's say for arguments sake, their FS is 1.25 which gives us a yield or failure value of 39,85.5 psi. When designing buildings in my structural engineering mode, I aim for a FS not less than 1.5...go figure.
I have talked with people who shoot Sabatti .45-70 DRs and they are using Garrett 420 grain bullets at 35,000 psi with, as they claim, no damage..so far.
Opinion only and not to be construed as professional advice...32,000 psi seems OK.
Eagle One, MSE, PE
Professor of Chemistry, Physics, Thermodynamics, Mathematics
quote:
Originally posted by Eagle One:
Several manufacturers are using BAR nomenclature. Here are some units and conversions:
1 BAR = 100,000 N/m^2 = 100,000 Pascals (Pa).
Since F=ma, and Newton (N) is a unit of force, we get, in the metric system N = kgm/s^2.
kilogram (kg) is a unit of mass.
Now, 1 BAR = 14.5038 psi and 1 psi = 0.06894747 BAR.
Correctly, 2200 BAR = 31,908.4 psi.
I teach thermodynamics and checked for HST pressure. Not defined in any of my thermo or mechanical engineering books. But, H is enthalpy, S is entropy, and T is temperature.
Finally, a steady diet of 32,000 psi. Only 92 psi more than approx 31,908.4 psi. All manufacturers build in a factor of safety (FS) in their product. You'll never find out what it is unless you can get to the closely held proof data. All that said, what is your confidence in Baikal? Let's say for arguments sake, their FS is 1.25 which gives us a yield or failure value of 39,85.5 psi. When designing buildings in my structural engineering mode, I aim for a FS not less than 1.5...go figure.
I have talked with people who shoot Sabatti .45-70 DRs and they are using Garrett 420 grain bullets at 35,000 psi with, as they claim, no damage..so far.
Opinion only and not to be construed as professional advice...32,000 psi seems OK.
Eagle One, MSE, PE
Professor of Chemistry, Physics, Thermodynamics, Mathematics
Thanks, I used one atmosphere for the definition of Bar, which I remembered as 14.7 PSIA, I should have looked in Wikipedia or something.
I knew what h, s and T were abbreviations for but couldn't figure out how they related to pressure. The warning on my barrel is the first time that I've seen "HST" used for any pressure units.
Thanks again,