Here's a topic to debate.....

[ProfJohnL]

A Ton of lead comes down from a, Church roof quicker thant a Ton of feathers. :evil:

Oh I don't know I agree with that. Firstly it depends on where the church is what about the moon for example. And secondly haven't you seen the flock of birds that take off from the roof of the church when the local wig lets off his shot gun, Ill bet they take off much quicker than the travelling thieves can strip the lead.

Now for nitrogen filled tyres. The AA have posted this comment

http://www.theaa.com/motoring_advice/safety/filling-tyres-with-nitrogen.html
I whole heartedly agree, and as such I would not elect to have a nitrogen fill except where its not charged as an extra, and the tyre costs are competitive.

Incidentally I have just had some of the new Good Year efficiency tyres fitted to my Passat, and even allowing for the difference any new tyre would make over a worn tyre, they do seem to offer superior road holding and are definitely quieter, and the nitrogen fill was not charged as an extra.

 

[Hutch]

Nobody has come back with the fact that compressed air, with it 20% oxygen is corrosive due to the Oxygen, and with the increase of alloy wheels not good.
At least in aviation, dry nitrogen is used for this reason. And due to the very high temperaatures that aircraft tyres get to during take off and landings, they can end up taxying for over four miles and at weights of over 150 -200 tonnes, thats a lot of heat generated, you do not want explosive oxygen in your hot tyres.
I had some goodyear Hydra grips on a vectra 2.0 cdti great grip, but worn out easily.
Merry Xmas to all,

 

[JonnyG]

Nobody has come back with the fact that compressed air, with it 20% oxygen is corrosive due to the Oxygen, and with the increase of alloy wheels not good.
At least in aviation, dry nitrogen is used for this reason. And due to the very high temperaatures that aircraft tyres get to during take off and landings, they can end up taxying for over four miles and at weights of over 150 -200 tonnes, thats a lot of heat generated, you do not want explosive oxygen in your hot tyres.
I had some goodyear Hydra grips on a vectra 2.0 cdti great grip, but worn out easily.
Merry Xmas to all,

Actually it is the water vapor that is present in AIR that is corrosive not the Oxygen ...

 

[Hutch]

JonnyG, dont let this be a TLDR, (To Long Didnt Read). Oxidizing compounds Oxygen gas (O2) is a pretty good oxidant (in fact, the word "oxidize" comes from "oxygen"). This is because oxygen is fairly electronegative. When bonded to itself, it forms a purely covalent bond. In contrast, when bonded to many other elements, in particular to less electronegative metals, oxygen is able to have more electron density for itself. So oxygen gas will react with other elements, such as iron, and then rust or corrode them. Other very corrosive elements are F2, Cl2, and Br2, all for the same reasons -- they are very electronegative, and by combining with something other than themselves, they are able to gain more electrons. Also note that burning is the same process as rusting, although we don't think of it that way! Both are just something combining with oxygen. Compare the two reactions: Rusting of iron: 4Fe + 3O2 --> 2Fe2O3 Burning of methane: CH4 + 2O2 --> CO2 + 2H2O In fact, burning is just oxygen combining with the fuel (whether it be wood, oil, gas, coal, or anything else) to form products in which the reactants are oxidized. So oxygen is in fact quite reactive with many things. Usually to get things to burn, you need a spark to get the reaction burning though (there is an activation barrier to the reaction, but it is an very exothermic reaction). Rusting is also quite exothermic, but it is kinetically slow..
☺a good bit of fishing done by the Prof to start with.

 

[JonnyG]

JonnyG, dont let this be a TLDR, (To Long Didnt Read). Oxidizing compounds Oxygen gas (O2) is a pretty good oxidant (in fact, the word "oxidize" comes from "oxygen"). This is because oxygen is fairly electronegative. When bonded to itself, it forms a purely covalent bond. In contrast, when bonded to many other elements, in particular to less electronegative metals, oxygen is able to have more electron density for itself. So oxygen gas will react with other elements, such as iron, and then rust or corrode them. Other very corrosive elements are F2, Cl2, and Br2, all for the same reasons -- they are very electronegative, and by combining with something other than themselves, they are able to gain more electrons. Also note that burning is the same process as rusting, although we don't think of it that way! Both are just something combining with oxygen. Compare the two reactions: Rusting of iron: 4Fe + 3O2 --> 2Fe2O3 Burning of methane: CH4 + 2O2 --> CO2 + 2H2O In fact, burning is just oxygen combining with the fuel (whether it be wood, oil, gas, coal, or anything else) to form products in which the reactants are oxidized. So oxygen is in fact quite reactive with many things. Usually to get things to burn, you need a spark to get the reaction burning though (there is an activation barrier to the reaction, but it is an very exothermic reaction). Rusting is also quite exothermic, but it is kinetically slow..
☺a good bit of fishing done by the Prof to start with.

wow.. where did you find that.. but i thought we were talking Alloy wheels and Alloy wheels are normally of an ALUMINIUM or MAGNESIUM ALLOY ..not Iron....oxidisation of Alloy wheels in itself stops anymore oxidisation taking place as it forms a thin protective layer by there very nature Alloys are far far less corrosive than single metals hence their use. and i would not use oxidation of an Alloy wheel a reason to use pure Nitrogen. but i do use nitrogen in my cars and motorcycles and indeed my caravan . nitrogen atoms being bigger than oxygen ones they wont escape so easily .better temperature control of my tyres is another. and .no water vapour present ....

 

[Hutch]

No, beets me as well, sure the Prof will help.
Pino grigio, over takes, but oxgen corodes, water vapor is H2O , Hydrogen di oxide.
☺
Ok thread closed. Maybe☺

 

[JonnyG]

No, beets me as well, sure the Prof will help.
Pino grigio, over takes, but oxgen corodes, water vapor is H2O , Hydrogen di oxide.
☺
Ok thread closed. Maybe☺

stainless steel is a typical example of a reaction taking place with H2O WATER VAPOUR. Yes the oxygen in water.reacts and forms a very thin protective layer .I would hardly call it corrosion as corrosion keeps going till it eats away everything..

 

[Dustydog]

Hey Boys
Cut and paste is fine with me but please can you say when you do it,
Chemically speaking the combination of oxygen and hydrogen in air creates water which in various guises causes the problems.

 

[Hutch]

Stainless steel, is iron, chromion and carbon, this reacts to oxygen to give a self protecting surface, as does aluminium, ,but once the surface is broken the oxgen, in air, will start the deteriation process, (corrosion). And coreodeds from wirhin. Giving granular corrosion..
Wrong time of night to get my brain cells working. ☺

 

[Hutch]

Thanks Dusty dog, got there before, I got my answer, typed.

 

[Hutch]

Nitrogen is an Inert gas and as such does not react to be corrosive with alloys , steel or aluminium, ,Aluminum, as or brothers over the pond call it, may be different.

 

[ProfJohnL]

............... you do not want explosive oxygen in your hot tyres..............

Hello again Hutch,

"explosive oxygen" ????? Sorry but no, Oxygen is not explosive by virtue of its chemical properties, however it is required to allow a fuel to oxidise. Absence of an oxyident prevents fuel from burning or exploding. the only time oxygen can be explosive is if it compressed and the vessel containing it fails. mechanically the potential energy in the compressed gas ( and it could be almost any gas) will rapidly expand and may be dangerous, but its not the gas explodingas there is no chemical change. its on;y the vessel failing.

 

[Gagakev]

Oh Prof! What have you started?

My tyres are Round...they have the pressure checked before each trip... And they get me from A to B

 

[Craigyoung]

My tyres are Round...they have the pressure checked before each trip... And they get me from A to B [/quote] from gagakev ;

Short and sweet and simple , same here . Car checked regularly.

 

[Dustydog]

I've just had a momentary lapse of reason.
What the heck are we all on about????
My first alloy wheel car was out of 1986. It did 99k miles no problem with wheels at all

Have we missed something :huh: :huh: hmy:

 

[Craigyoung]

Modern technology !

 

[Craigyoung]

Modern technology dusty

 

[Gabsgrandad]

Yep! - Folks are at a loose end and boredom setting in !

 

[Hutch]

Gabs, you are correct, Prof you are correct, , good thread..

 

[ProfJohnL]

........................ At least in aviation, dry nitrogen is used for this reason. And due to the very high temperaatures that aircraft tyres get to during take off and landings, they can end up taxying for over four miles and at weights of over 150 -200 tonnes, ................,

Its just occurred to me that this statement is a little exaggerated. Yes some aircraft do weigh in at several hundred tonnes, but they usually have multiple tyres so the single static load on a tyre is only about 50 tonnes. That is still a lot compared to a car tyre, and it doesn't take into account the bump loading when landing. It would be interesting to know what the difference is between the expected static and dynamic loads are for a large jet

 

[saint-spoon]

I am enjoying this topic for some reason although we are going around in circles a bit and I am yet to be convinced that a nitrogen fill of the tyres makes any discernible difference for domestic use. I could however throw in a hypothesis about nitrogen. The process by which oxygen is distilled (if that is the correct term) from air produces a lot of dry nitrogen as a by-product. Companies such As BOC make a lot of oxygen for medical and other uses and will therefore have a lot of nitrogen which can be of use. Dry nitrogen is incredibly useful stuff for refrigeration technicians (I was one once) for drying and pressure testing fridge systems (fridges don’t like any moisture within the refrigeration circuit). I am lead to believe that cream flow ales use nitrogen as the gassing agent as well and that the preservative atmospheres in packaged food. Whilst in aviation where there are huge temperature differentials or for racing cars where the smallest of differences can make all the difference to the performance of the vehicle, I cannot however see how these make any difference to towing vehicles of caravan wheels. I would suggest that as racing cars use it someone saw a marketing opportunity for those that are easily impressed. As for leaking out more slowly, the difference in size between an oxygen molecule and nitrogen molecule is insignificant. I think that there was a by product that was being used by the racing industry that someone realised that they could market to domestic cars…

 

[Hutch]

Sorry Prof, can't give you an answer, but an aircraft is just thousands of rivets flying in close formation.

 

[Humphrey]

Sorry EH52ARH its more like wire, wood, fabric and glue, cutbacks, recession etc

 

[Gagakev]

I am enjoying this topic for some reason although we are going around in circles

Around in circles....my head is spinning.....

 

[Gafferbill]

........my understanding is that the only advantage of using Nitrogen to inflate tyres is to minimise fire risks involved when a tyre catches fire and a subsequently rapid deflation occurs.
Tyre fires can have catastrophic consequences in Aviation and Motor Sport.
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The following is a quote from a Boeing Press Release................

Boeing has received reports of three confirmed cases and other suspected cases in which a wheel/tire assembly exploded when the oxygen in air-filled tires combined with volatile gases given off by a severely overheated tire. In one case, the tire became overheated as a result of a dragging brake, and the wheel/tire assembly exploded when it reached the auto-ignition temperature. In another case, a wheel/tire assembly explosion in the wheel well during flight was suspected in the catastrophic loss of one airplane. A similar explosion caused severe damage to two others.

As a result, the U.S. Federal Aviation Administration issued Airworthiness Directive 87-08-09 requiring that only nitrogen be used to inflate airplane tires on braked wheels. However, tires may be topped off with air in remote locations where nitrogen may not be available if the oxygen content in the tire does not exceed 5 percent by volume.