T&T: Nitrogen in RIB

[Jim Gano via Trawlers-and-Trawlering]

Strange summer question :

I have a 10 foot Caribe RIB on the back of my boat.  It is under a dark blue sunbrella cover.  During the heat and sun of the day (Orange Beach Alabama) the tubes are nice and hard.  After the sun sets and the temp drops into the upper 70s (Fahrenheit) the tubes get real soft (so soft I would not want to launch without putting in more air).  I know that some auto places can fill car tires with nitrogen and this keeps the tire air pressure more constant.  Has anyone ever tried this on a RIB?  If so, did it make any difference and how was it done?
 Jim Gano
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[Peter Denton via Trawlers-and-Trawlering]

Hi Jim
Since oxygen and nitrogen are next to one another in the period table the
molecular weights are quite close. In general the simple physics which
links pressure temperature and volume don't have much to do with molecular
composition.

It is true however that as the partial pressure of oxygen increases the
more reactive it becomes, whereas nitrogen is only reactive at extremely
high pressures. The carbon in rubber might then be more vulnerable to
degradation in the presence of oxygen.

I'm only saying these things from memory and perhaps there is someone else
out there who could bring to bear more pertinent ideas.

And then there would be the problem filling the RIB, you would have to get
a tank of high-pressure nitrogen with a low pressure controller and
specialized fittings.

Besides that,like so few things nowadays air is free And pumping is good
for the cardiac arteries.

Peter Denton

[Sean Welsh via Trawlers-and-Trawlering]

On 08/04/2015 11:06 AM, Jim Gano via Trawlers-and-Trawlering wrote:
> ... I know that some auto places can fill car tires with nitrogen and this keeps the tire air pressure more constant.

No, it does not, although people who sell nitrogen filling systems would
like you to believe this (and other myths).

Plain air is already 78% nitrogen. While in certain environments (for
example, where a risk of explosion exists), removing the oxygen from the
mix (about 21% of plain air) makes sense, it will not change the rate at
which the gas expands and contracts (in, for example, a RIB heating up
in the sun) nor will it change the rate at which the gas escapes the
containment through microscopic leaks or permeation.

About the only claim made by nitrogen-fill suppliers that actually has
any merit is that the bottled gas is much drier than plain air, and
moisture is bad for lots of things (metal valve parts, wheels, etc.).
High moisture content *might* conceivably affect expansion and
contraction rate as well, but you'd need quite humid air to do that.

If you want the dryness benefits, use an air compressor to fill/top your
dingy and add an air dryer to the output, about $30 or so.

FWIW.

-Sean
m/y Vector
lying Manhasset Bay, NY
http://OurOdyssey.BlogSpot.com

[David Sorenson via Trawlers-and-Trawlering]

Don't forget that atmospheric air is comprised largely of Nitrogen already

David Sorenson
Duluth, MN

[Rich Gano via Trawlers-and-Trawlering]

I switched to nitrogen fill for my two vehicles some years back, and from
empirical evidence, there is a marked improvement in the stability of the
tire pressure. I virtually never have to mess with tire pressures as the
seasons change and don't even think about refilling anymore because the tire
pressure was so consistent for years. Yes I know, air is mostly nitrogen,
but that bit of oxygen apparently makes a lot of difference. There is the
added benefit of the non-reactive nature of nitrogen inside the tire meaning
no internal tire rot. The Navy has used nitrogen in its carrier aircraft
for many years, and I suspect airlines do as well to lessen the chance of
fire s the result of tire blowouts.

Rich Gano
2005 Mainship 30 Pilot II
Panama City, FL

[Peter Denton via Trawlers-and-Trawlering]

Hi Rich.

I'd certainly be interested to hear about the physical laws that keep your
tires steady. Must've been something they didn't tell me when they gave me
my PhD. I'm going to sue the scoundrels. Certainly the pressure spike of
momentary impact of a wheel on an aircraft could diminish the danger of a
explosive blowout.

But as to the question of steady pressure you are going way out on a limb
well way past magic mystery oil.
I keep on trying to tell you guys about the value of anecdotal evidence.
The guys who put the probe around Pluto have little appetite for anecdotes,
only facts.
Then again what comes around goes around. The guys who sell you the
nitrogen probably have a very nice trawler of their own.

PHD, PhD

[R C Smith Jr via Trawlers-and-Trawlering]

You guys got me curious and I found this:

In 2006, Consumer Reports conducted a year-long study to determine how much
air loss was experienced in tires filled with nitrogen versus those filled
with air. The results showed that nitrogen did reduce pressure loss over
time, but it was only a 1.3 psi difference from air-filled tires. Among 31
pairs of tires, the average loss of air-filled tires was 3.5 psi from the
initial 30 psi setting. Nitrogen-filled tires lost an average of 2.2 psi
from the initial setting. Nitrogen won the test, but not by a significant
margin.

​I would guess that dinghies, ​with much lower pressures, would have
virtually negligible difference.

Thanks,
Bob
__________________________
Robert Calhoun Smith, Jr.

*M/V MARY KATHRYN Hatteras 58 LRC MTOA #4861Annapolis, Maryland*

[Jim Gano via Trawlers-and-Trawlering]

Thanks to all who commented....  I too was sucked in by the advertising and hype of nitrogen... I did my research and read several studies (and actual tests) where the pressure benefits of nitrogen where disproved... All I really needed to do was remember the formula for the gas law... PV=nRT (for those who remember)...  Jim Gano

[Fred Sorensen via Trawlers-and-Trawlering]

Boyle's law has not been repealed and as has been pointed out air is 78% or so nitrogen to start with. A dry gas is nicer than a not-dry gas but that won't solve your night time deflation problem.
Remember to change feet once in a while when pumping up your RIB to get equal exercise in both legs....

Fred Sorensen
OA 43
Treasure Island, FL

Sent from my iPad which is responsible for all grammar errors.

[Ken Bloomfield via Trawlers-and-Trawlering]

I would not be so quick to eliminate the idea of pure nitrogen as a leak
rate reduction. Here is a link to a proper study of the effects of
nitrogen in tires. I won't pretend to be able to extrapolate the effect
to a dinghy, but it does look like there is value in doing so.
http://getnitrogen.org/savebillions/files/Clemson_NitrogenFilling_FinalReport.pdf

Regards,
Ken Bloomfield
m/v Tellico Lady

On 8/4/2015 11:06 AM, Jim Gano wrote:
> Strange summer question :
>
> I have a 10 foot Caribe RIB on the back of my boat. It is under a dark blue sunbrella cover. During the heat and sun of the day (Orange Beach Alabama) the tubes are nice and hard. After the sun sets and the temp drops into the upper 70s (Fahrenheit) the tubes get real soft (so soft I would not want to launch without putting in more air). I know that some auto places can fill car tires with nitrogen and this keeps the tire air pressure more constant. Has anyone ever tried this on a RIB? If so, did it make any difference and how was it done?
> Jim Gano

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[Ken Buck via Trawlers-and-Trawlering]

This topic comes up in the RV world quite often. The experts all have their
say about how nitrogen and oxygen are so close it doesn't make any
difference in RV tires. Besides, air, they propound is already 78% nitrogen and
just 21% oxygen, so it's almost all nitrogen anyway. Let's take H2O. Just add
one more molecule of O to the compound and make it H2O2. It's almost
water...... right? No, it's hydrogen peroxide and at full strength it will eat
the skin off your bones and leave those bones a real nice bright white. But
it's really close to just plain water. There can't be much difference,
right? .Small amounts of different elements can make a big difference in the
resulting compound. Would you breath air that had just 1% carbon monoxide
added? It's just 1%.

I wonder where we'd be in life if we listened to the experts who said
Einstein was crazy, Gallileo was off his rocker, Shakespeare was writing drivel,
and man can never reach the moon? If you want to try it, put the rib on
the trailer and run it up to Costco and see if they'll give you a hand with
your experiment. Fill one tube with nitrogen and then see what happens. Of
course we all know that the "scientists" all agree that an airplane can't
fly. It's simply impossible due to physics they say.

Ken