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Eh?

Where did 14.7 come from? I didn't make the figures above up...

You can work it out the other way if you like: work out the force of 1 bar in kg/square cm (1 x 1.019 = 1.019kg/sq cm)

and using 1" = 2.54cm work out kg/sq in (2.54 x 2.54 x 1.019 = 6.574 kg/sq in)

then taking 1kg = 2.204lb work out PSI
(6.574 x 2.204 = 14.489psi)

Therefore 1bar = 14.5 psi (allowing for rounding to 3 decimal places, this is near enough)

Any further questions, please see me after class.

Martin (who's bored at work)

BTW all above figures came from the posted website.
 

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Re: Eh?

Stunned Monkey said:
Where did 14.7 come from?
If this is not rhetorical I will tell you, 1 atm is 760mm of Mercury as first theorised by Torricelli and Demonstrated by Viviani.


Stunned Monkey said:
Any further questions, please see me after class.
Martin (who's bored at work)
[/B]
Must have been bored in the Physics lesson that day too.
 

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"If this is not rhetorical I will tell you, 1 atm is 760mm of Mercury as first theorised by Torricelli and Demonstrated by Viviani. "

So why does that make 1bar = 14.7psi?

Answer: it doesn't. Some people haven't been reading posts correctly. It was stated higher up that 1 bar = 14.7psi in some cases, confusing 1bar with 1atm.

Martin
(A-level in Physics, and Maths (involving Mechanics), and Degree module in mechanics - not that this means much, except that I did sleep a lot in class...)

PS Actually 1 atmosphere = 760.0021 mm mercury (@ 0 C)
 

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I always avoid going for the last possible decimal place as it seems a little too anal, we are on dodgy ground as it is with the discussion.

Dr Iain Morse-Wiltshire.
(20yds swimming certificate Hilsea Lido 1978, Good Behaviour Gold Star, Mrs Edwards class 1975)
 

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Mycroft said:
Just to make it plain.

1 bar =14.5psi
1 Atm = 14.7psi
Interesting, why are the values different? I understood what you were saying about how they're used to describe different things but why should the values be different? Where did bar come from? I had thought that bar was supposed to be mean atmospheric pressure at sea level but now it seems that it isn't.
 

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This is getting a way off topic but we might as well complete the circle and this is the simple version and, please, the end!

Bar is an absolute measure and can be used for calculations for the design of scuba gear, Oxy-acetylene bottles etc it is an International scale that has its root in the Scientific scale, Pascals.
1bar = 100000 Pascal.
In complex design calcs have nice round units makes for ease of cumbersome quantities.

Atm. is a gauge pressure reading and because it has no standardised simple number it has been variously called Atm, Atg, Ata and Atu, so it was dropped from the from the SI.

It is now mostly a meterological unit and simple common unit and is used by Motor engineers to denote the change from Natural induction and forced induction, this is exactly as (most) of us have been using it.

END. :D
 
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