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· "Three sheds"
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Pressure is directly proportional to temperature.

Except that:

1) You have to work in Absolute Temperature (Kelvin) To convert Celcius to Kelvin add 273. Eg 27 degrees C is about 300 K

Hence a 1 degree drop at 27 deg C changes the pressure by a factor of 1/300, which (assuming 200 bar in the tank) is 2/3 of a bar which is (200 x 1/300) = 0.66 bar (as previous posters said) You get a smaller drop in pressure for more empty tanks, and a higher drop for higher pressures of tanks

2) Also, things go screwy over around about 250 bar, and the laws become non-linear (ie pressure is no longer proportional to temperature)

Laters,
   Janos
 

· "Three sheds"
Joined
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12,615 Posts
Imported post

[b said:
Quote[/b] (Digger @ April 03 2004,02:07)]Well, that's confused hell outta me!
Bugger. I must be some sort of anti-explainer. I take stuff you understand and talk at you until you don't.  


Hmmm. I'll bring graph paper and a pen to the Easter trip. I bet you're looking forward to that now.

But basically, a temperature change of 1 degree will cause a change in pressure of 0.33%. Ie 0.8 bar if you've got 250 bar in your tank, 0.66 bar if you've got 200 bar in your tank, 0.16 bar if you've only got 50 in to start with.

Above 250 bar things go screwy, and it's not .33% anymore.

Laters,
   Janos
 
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