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Old 25 January 2011, 07:26   #1
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tubes pressure / temp variation

Hi,

I have got a boat that I have been looking after for a customer for a while, as it is stored outside the tubes go soft when cold and firm up in warmer weather. The customer does not really believe/understand the difference the temperature can make to the boat tubes pressure.

Is there a slightly more scientific way for me to explain it to him, i.e 10% pressure loss for every 10 degrees or something similar?

Thanks
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Old 25 January 2011, 07:48   #2
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You could get the dumb cluck to watch this:


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Old 25 January 2011, 08:26   #3
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From memory:

Gay-Lussacs law states P1/T1=P2/T2 but you must bear in mind that the temperatures are Absolute so you can't say a doubling of temperature of say 10 degrees to 20 degrees will double the pressure. There's a little constant of 273 degrees to account for in that as well......

HTH
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Old 25 January 2011, 08:33   #4
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tell him to blow a balloon up. then stick it in the freezer over night and look at it in the morning

Or tell him stand outside for 4 hrs in his underwear and see how small and soft things can get
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Old 25 January 2011, 09:12   #5
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If you want to impress him, hold a PET water bottle mouth down over a steaming kettle for a bit. Replace the cap. Run the bottle under a cold tap. Bottle shrinks dramatically.
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Old 25 January 2011, 09:25   #6
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Cold air is denser than warm air, simples.
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Old 25 January 2011, 09:46   #7
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Lets hope he doesn't decide to take up scuba diving
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Old 25 January 2011, 10:10   #8
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Sell him an automatic compressor and fit him pressure relief valves. The tubes will always be perfect and no need to worry about any of that science stuff.
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Old 25 January 2011, 10:30   #9
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as we live in one atmosphere of air all the time will the tubes have this added to the 2psi we blow them up to, so if this is the case my tubes have 16.7 psi of air in them, or am i torkin bollox
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Old 25 January 2011, 10:36   #10
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Quote:
Originally Posted by biffer View Post
as we live in one atmosphere of air all the time will the tubes have this added to the 2psi we blow them up to, so if this is the case my tubes have 16.7 psi of air in them, or am i torkin bollox
The tubes do having 16.7psi in them but a gauge reading gauge pressure will only read 2 psi due to atmospheric pressure.
If you use a gauge that reads absolute pressure then it will read 16.7 psi.
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