The name 'pascal' was adopted by the CGMP in 1971 and appeared on U.S. tires
in the late 70s. Yet thirty years later, the old metric countries are still
fumbling around with a mishmash of obsolete metric pressure units. If these
countries find it so difficult to add a couple of zeroes to their tire
pressures and express them correctly in kPa, they shouldn't feel smug about
America's inability to give up its old units.
Here are the 48 pressure units I've encountered (abbreviations or names.
Some of you may not see the proper superscript 2.). Notice that two-thirds
of these units are "metric," though many are synonymous or virtually
identical. Is it any wonder that people think metric is complicated and
confusing?
The starred (*) values are exact definitions. In ascending order of size:
barye = 0.1* Pa
�bar = 0.1* Pa
dyn/cm� = 0.1* Pa
tor [obsolete name] = 1* Pa
pdl/ft� = 1.488 Pa
ft of air (60 �F) = 3.656 Pa
mmH2O = 9.8064 Pa
kg/m� = 9.806 65* Pa
kgf/m� = 9.806 65* Pa
kp/m� = 9.806 65* Pa
daPa = 10* Pa
psf = 47.880 Pa
lb/ft� = 47.880 Pa
lbf/ft� = 47.880 Pa
cmH2O (4 �C) = 98.064 Pa
g/cm� = 98.0665* Pa
gf/cm� = 98.0665* Pa
mb = 100* Pa
hPa = 100* Pa
torr = 133.3224 Pa
mmHg (0 �C) = 133.3324 Pa
"WC = 249 Pa
ozi (osi) = 430.922 Pa
ozf/in� = 430.922 Pa
pieze = 1* kPa
sn/m� = 1* kPa
ftWC = 2.989 kPa
inHg (60 �F) = 3.377 kPa
inHg (32 �F) = 3.386 kPa
psi = 6.8948 kPa
lb/in� = 6.8948 kPa
lbf/in� = 6.8948 kPa
db (decibar) = 10* kPa
ftHg (32 �F) = 40.637 kPa
tonf/ft� = 95.8 kPa
at (technical atmosphere) = 98.0665* kPa
kg/cm� = 98.0665* kPa
kgf/cm� = 98.0665* kPa
bar (b) = 100* kPa
hectopieze = 100* kPa
atm (standard atmosphere) = 101.325* kPa
N/mm� = 1* MPa
ksi = 6.895 MPa
kip/in� = 6.895 MPa
kg/mm� = 9.806 65* MPa
kgf/mm� = 9.806 65* MPa
kb = 100* MPa
dB (sound pressure amplitude in pascals = 2 x 10^(0.05 L - 5), where L is
the unweighted sound level in dB)
