I thought the point of SI was to unify the use of units so everyone could speak the same language? On this ventilator I am find many ways of expressing the same pressure and flow rates. Pascals mmH2O cmH2O mBar and another one I didn't even recognize. lol Likewise I'm finding flow rates indicated as either ml/s SLM (standard liters per minute) WTF?! Why have multiple units like this? This is all in the same field really. People just like to use different units. Damn them to hell!!! -- Rick C. - Get 1,000 miles of free Supercharging - Tesla referral code -

Historical reasons and being 'understandable'- the same argument as for Imperial units. Out of those only one is part of SI. The medical people are mostly using cmH2O around here, but that's conviniently close enough to 1 hPa / 1 mbar. Part of design co-operation should be defining and enforcing the units to reduce possible mistakes. Gases are compressible and the correct unit should be g/s ;-) And then there are absolute and gauge pressures, which you also need to take into account with ventilators and code! Fully agreed. But I find that fight one I can't win and thus propose minimally error prone common units. Of course sometimes the 2% error can make a difference.. -- mikko

Why So Many Units?

Jul 20, 2020 61 Replies

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Robert Lacoste 5 years ago

(..)

Fully agreed ! Same for the languages : Why don't we just all speak french ?

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Tony Stewart 5 years ago

For the same reason USA will never go metric.

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