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Old 18 November 2013, 07:27   #1
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Temperature bursting a Rib?

I just wondered whether there have ever been cases of a change in temperature causing the tubes of a Rib to burst?

(P1.V1) / T1 = (P2.V2) / T2 and all that.
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Old 18 November 2013, 07:29   #2
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Yes. Even with overpressure valves, it has happened...
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Old 18 November 2013, 07:41   #3
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Yes. Even with overpressure valves, it has happened...
I had to put an awful lot in over the weekend. Just to be sure, I'll let some out again.

(An ideal opportunity to use the word "flaccid", but I haven't)
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Old 18 November 2013, 08:13   #4
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It would need to be pumped hard when cold and then parked up in sunlight. You'd also need to have a sticky overpressure valve...

Chances are low - but -
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Old 18 November 2013, 08:32   #5
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if you do the physics you'll see that temperature change on air will make not a huge amount of difference to the pressure. However, any moisture in the tube has the potential to make much larger fluctuations.

*I* believe that the biggest impact of temperature is it softens the glue - afterall that is how you 'unstick' patches etc. Combined with a little extra pressure a weakened joint may pop.
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Old 19 November 2013, 04:55   #6
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*I* believe that the biggest impact of temperature is it softens the glue - afterall that is how you 'unstick' patches etc.

Can't see that myself. The temp of a hot air gun is considerably more than a hot summers day. So going on your theory, there'd be a lot of deflated tubes around the med, caribean etc
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Old 19 November 2013, 07:19   #7
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[QUOTE=Poly;583177]if you do the physics you'll see that temperature change on air will make not a huge amount of difference to the pressure. However, any moisture in the tube has the potential to make much larger fluctuations.]

OC to 30C is about 10% increase in pressure. Moisture-wise I would have to dig out my steam tables.

Nitrogen-filled tubes here we come!
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Old 19 November 2013, 07:29   #8
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Put your hand on a rib sat in very still air, in the mid day sun (summer in wales) on a beach, it gets very hot, maybe even 50 deg c.....
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Old 19 November 2013, 09:55   #9
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Yes, but thats the temp of the tube, which may not be the temp of the air inside it. How well does the tube conduct heat to the air in it ?
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Old 19 November 2013, 10:25   #10
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I've often wondered about this. Trailering the boat in CA i can encounter 50+ degree F temperature swings in the summer. It will be 55F and foggy in the coast and 100+F inland and back again. I usually stopped a few times and deflated and inflated as I didn't want to find out the hard way if they could burst.

On a side note I just recently purchased a pressure gauge and discovered that I have been filling my tubes too low. I was usually down around 1.5 PSI.

Jason
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Old 19 November 2013, 13:21   #11
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i used to have problems when i lived up high in the pennines of west yorkshire , village was over 1000 feet above sea level it was a constant battle at times especially if it was colder & foggy when at the coast .
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Old 19 November 2013, 14:00   #12
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i used to have problems when i lived up high in the pennines of west yorkshire , village was over 1000 feet above sea level it was a constant battle at times especially if it was colder & foggy when at the coast .
Which village was that the mc ?
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Old 19 November 2013, 14:07   #13
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Which village was that the mc ?
Mountain , Queensbury ,Nr Bradford . Tuther side of big hill to you lol
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Old 19 November 2013, 14:22   #14
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My flatacraft was sitting in the sun in a very sheltered car park after a weekend cruising I suspect the heat caused the seam to come apart about 12-18" The previous evening had been clear and cold no over pressure valves in those days
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Old 19 November 2013, 14:29   #15
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Yes, but thats the temp of the tube, which may not be the temp of the air inside it. How well does the tube conduct heat to the air in it ?
How hot is the air in your car when you leave it closd up on a sunny day?

Air has a fairly low specific heat, so the air in the tubes gets hot. Potentially hotter than the tubes.

My local waters are never more than about 52F. On hot days I always vent, sometimes before even pulling it out of the water since bursting a seam is going to be a disasterous expense.
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Old 19 November 2013, 16:00   #16
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The Zodiac manual for my SIB advises for every 1*c rise in temp increases the internal air pressure by 4mb / 0.06psi. How accurate this is I know not!
Usually leave mine inflated at half pressure (120mb) whilst not in use/with cover on during the summer months.
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Old 19 November 2013, 17:57   #17
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The Zodiac manual for my SIB advises for every 1*c rise in temp increases the internal air pressure by 4mb / 0.06psi. How accurate this is I know not!
That seems about right so typical daily temp change (UK summer) is only the difference between really high and really low pressure weather systems.
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Old 19 November 2013, 18:05   #18
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Can't see that myself. The temp of a hot air gun is considerably more than a hot summers day.
you heat gently with a hot air gun, what temp does tube get to? Ever touched a black tube that has been sitting in the sun all day?

Quote:
So going on your theory, there'd be a lot of deflated tubes around the med, caribean etc
Notice that dark coloured tubes are less popular in the hot - perhaps for comfort but also for longevity? they may also be more aware of the issue and take better care.
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Old 19 November 2013, 18:07   #19
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You accounting for the fact that a tube in contact with water will be say 5-10C and so if pumped up to pressure for that temp and then brought ashore in the afternoon and left in the bright sun it might rise to 70C (you remember sitting in shorts in the back seat of 1970's cars with fake leather seats??) so say a 60C shift. Thats an extra 3.6PSI?

Not sure what pressure people pump their RIBs up to 2PSI rings bells... nearly three times that...?

Solution: get solid tubes ?
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Old 19 November 2013, 18:18   #20
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you heat gently with a hot air gun, what temp does tube get to? Ever touched a black tube that has been sitting in the sun all day? Notice that dark coloured tubes are less popular in the hot - perhaps for comfort but also for longevity? they may also be more aware of the issue and take better care.
I had old polyurethane tubes on a tornado that came apart at the seam on a hot day- but only the 12" or so section of seam underneath a black wear patch. The glue had softened with the heat absorbed by the black patch; the surrounding orange areas were unaffected.
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