• MisterFrog@lemmy.world
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      13 hours ago

      As much as hPa is legitimate, in English speaking contexts I wish we kept to 10^3 prefixes. (Pa, kPa, MPa, GPa etc).

      Like how we keep to nm, μm, mm, m, km. Mostly.

      Or if one really must, atmospheres. Other units are just more of a pain to convert between, like yeah, it’s metric, so it’s not THAT hard, but just nicer in my opinion if it’s consistent intervals.

      Alas, at least I very rarely need to deal with PSI. Only with valve manufacturers using imperial valve coefficients (Cv values), grumble, grumble. They don’t even include the units usually, which to me is heresy. The units are US gallons/min of water at 60 °F per pressure drop of 1 PSI. Like, US engineers have this really stupid habit of not including units in constants and coefficients in some contexts, drives me up the wall.

      Thanks for being the convenient recipient of this metric engineer’s unit rant.

      • Thorry84@feddit.nl
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        7 hours ago

        As far as I know hPa is the preferred unit for air pressure and is used a lot. Usually referring to the air pressure of the atmosphere.

        Also hectometer is used a lot when talking about land measurements. And we don’t mostly keep to mm and m, in my experience cm is the most used and most useful measurement for every day objects.

        All of the different prefixes are valid and are used. It just depends on what context, which one is the most useful. No reason to stick to the 10^3 units, just use them all.

    • 9point6@lemmy.world
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      1 day ago

      I find bar more intuitive even if it’s just hPa/1000

      Nearly 7 bar is impressive for any tyres

      • MentalEdge@sopuli.xyz
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        1 day ago

        Any car tire.

        For road bicycles 7 bar is just “normal”, 8 and above isn’t unheard of.

        A guy once asked if I was crazy when I was pressurizing my hybrid bike to 6 bar, and I just pointed to the sidewall where the rating said 4.5-6.5 bar. The range is wide because the pressure you should use varies depending on what you weigh, and how you want to balance rolling resistance vs comfort.

        And even then the safety margin on bike tires is more than double the max rating, so it’s perfectly safe to go a full bar over if you want.

      • teletext@reddthat.com
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        1 day ago

        100 psi
        14400 lbf/ft^2 (pounds-force per square foot)
        1600 ozf/in^2 (ounces-force per square inch)
        689.475729 kPa (kilopascals)
        689475.729 Pa (pascals)
        6.80459639 atm (atmospheres) (unit officially deprecated)
        6.89475729 bars
        68.9475729 dbar (decibars)
        6894.75729 mbar (millibars)
        5171.49326 Torr (torr) (unit officially deprecated)
        5171.49252 mmHg (millimeters of mercury)
        203.602068 inHg (inches of mercury)
        70.30696 m WC (meters of water column)
        0.07030696 km WC (kilometers of water column)
        230.6659 ft WC (feet of water column)

        • Kitathalla@lemy.lol
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          1 day ago

          I didn’t know Torr was deprecated… For some reason that was always the number for STP I could remember in physics.