You got pascal, bar, psi, atm, torr, and all kinds of column heights of mercury, water and whatnot.
Why do we need all these different units to express pressure?
In: Physics
They’re all just conventions based on how the industry evolved. They can (mostly) all be directly correlated back to pascals. You’re probably accustomed to the concept of the notation of mass-force, even if you aren’t consciously aware of it: kg or lb being used as a unit of force, despite being defined as a unit of mass. This is just another convention which makes it easier to understand the situation at hand.
Though some units incorporate correction factors intrinsically in non-obvious ways. Specifically column heights – if they’re uncorrected (not referencing a standard temperature, e.g. 20 C), they can float as a result of temperature at the point of measurement, which can be useful in certain HVAC and weather applications.
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