Tire aging bombshell could cause harm

[1939mgtb]

only not as fast or as radically.....since air is only 80% N. the other components of air expand at a far higher rate. such as the 14% O2. and that is why we use nitrogen in high speed aircraft tires. Best, Ray "Spes mea in Deo est"

----- Original Message ----- From: "Robin Montgomery" RMontgomery@doriandrake.com> To: mg-tabc@yahoogroups.com> Sent: Wednesday, September 28, 2005 11:56 PM Subject: RE: [mg-tabc] Tire aging bombshell could cause harm > Nitrogen - as a gas - will expand with increasing temperature and its > behaviour is subject to exactly the same laws of physics as air, of which > it > is a major component. > > > Regards, > > Robin Montgomery > _________________________________ > > -----Original Message----- > From: mg-tabc@yahoogroups.com [mailto:mg-tabc@yahoogroups.com] On Behalf > Of > sara e jenkins > Sent: Wednesday, September 28, 2005 4:07 PM > To: artfitz@sympatico.ca; paroor@t-online.de; 1939mgtb@comcast.net; > mg-tabc@yahoogroups.com > Subject: RE: [mg-tabc] Tire aging bombshell could cause harm > > the most common reson to use nitrogen to fill tires is to provide > extreramly > accurate milage measurements for rallies-unlike air the nitrogen doesn't > expand and contract with temperature so the tire size stays constant-i > have > never known of an old tire exploding-and i am talking about vintage car > rallies-as the resuly of nitrogen. > > > > > > > Yahoo! Groups Links > > > > > >

[FrankGraham]

Stan, You have to take molecular weight and size into account and the number of molecules of a gas per unit of volume. Equal volumes of different gases will not have an equal number of molecules so even if the coefficients of thermal expansion are similar the number of molecules that will expand or contract in response to a temperature change in two equal volumes of dissimilar gases will not be the same. In the narrow temperature and pressure range that a tire operates within, a tire filled with pure nitrogen will have negligible increase in rolling diameter and/or internal pressure with increased operating temperature compared to the same tire filled with air. -- Frank < frankgraham@msn.com > ______________________

----- Original Message ----- From: "Stan at Hotmail via OE" skurzet@msn.com> To: "FrankGraham" frankgraham@msn.com> Sent: Thursday, September 29, 2005 3:53 AM Subject: Re: [mg-tabc] Tire aging bombshell could cause harm > For practical purposes, I don't believe that's true. If memory serves, all > gases have nearly identical coefficients of thermal expansion. Assuming > Charles and Boyel's laws, are not prejudiced, and work the same on air as on > Nitrogen, the pressure should will be the same for equal volumes of each gas > at the same temperature. > > Stan

[Robin Montgomery]

The wizardry is in either the design of tyres or the attention given to them when under study. The Universal Gas Law applies to all gases (but not to vapors in mixed gas / liquid phases - as propane in a pressurised tank) and is - Pressure (absolute) x Volume, divided by Temperature (absolute) is constant for a given gas or gas mixture. (P.V/T = Constant) Atmospheric pressure is 14.7 lbs/in2 absolute. Add your tyre pressure to that for the total absolute pressure. Absolute zero temperature is -460 deg F. Temperature from absolute zero is designated degrees Kelvin (Scottish physicist - I first met TCs in the Kelvinside area of Glasgow). 32 degF is 492 degK. For tyres at approximately the maker's recommended pressure, variations in pressure in average driving will not have much effect on the TOTAL volume of gas in the tyre. Then V is almost constant, so that for most purposes P/T is constant. Heat the gas (any gas - helium through argon) by 50 F degrees (K degrees) or 10%, and the absolute pressure will also increase by 10%. Nitrogen has a molecular weight (MW) of 28. Air has a MW of 28.966. There is next to no difference in the ratios of their specific heats. The mass of air or nitrogen in a given volume at a given pressure will be within 3%. The average commercial tyre pressure gauge is probably about that accurate. This worked pretty well when I was at school, and for the 25 years that I have been selling gas handling equipment. Regards, Robin Montgomery _________________________________ -----Original Message----- From: 1939mgtb [mailto:1939mgtb@comcast.net] Sent: Thursday, September 29, 2005 9:04 AM To: mg-tabc@yahoogroups.com; Robin Montgomery Subject: Re: [mg-tabc] Tire aging bombshell could cause harm only not as fast or as radically.....since air is only 80% N. the other components of air expand at a far higher rate. such as the 14% O2. and that is why we use nitrogen in high speed aircraft tires. Best, Ray "Spes mea in Deo est"

----- Original Message ----- From: "Robin Montgomery" RMontgomery@doriandrake.com> To: mg-tabc@yahoogroups.com> Sent: Wednesday, September 28, 2005 11:56 PM Subject: RE: [mg-tabc] Tire aging bombshell could cause harm > Nitrogen - as a gas - will expand with increasing temperature and its > behaviour is subject to exactly the same laws of physics as air, of which > it > is a major component. > > > Regards, > > Robin Montgomery > _________________________________ > > -----Original Message----- > From: mg-tabc@yahoogroups.com [mailto:mg-tabc@yahoogroups.com] On Behalf > Of > sara e jenkins > Sent: Wednesday, September 28, 2005 4:07 PM > To: artfitz@sympatico.ca; paroor@t-online.de; 1939mgtb@comcast.net; > mg-tabc@yahoogroups.com > Subject: RE: [mg-tabc] Tire aging bombshell could cause harm > > the most common reson to use nitrogen to fill tires is to provide > extreramly > accurate milage measurements for rallies-unlike air the nitrogen doesn't > expand and contract with temperature so the tire size stays constant-i > have > never known of an old tire exploding-and i am talking about vintage car > rallies-as the resuly of nitrogen. > > > > > > > Yahoo! Groups Links > > > > > >

[1939mgtb]

Guess all those tire engineers are wrong..... Best, Ray "Spes mea in Deo est"

----- Original Message ----- From: "Robin Montgomery" RMontgomery@doriandrake.com> To: mg-tabc@yahoogroups.com> Sent: Thursday, September 29, 2005 12:39 PM Subject: RE: [mg-tabc] Tire aging bombshell could cause harm > The wizardry is in either the design of tyres or the attention given to > them > when under study. > > The Universal Gas Law applies to all gases (but not to vapors in mixed gas > / > liquid phases - as propane in a pressurised tank) and is - > > Pressure (absolute) x Volume, divided by Temperature (absolute) is > constant > for a given gas or gas mixture. (P.V/T = Constant) > > > Atmospheric pressure is 14.7 lbs/in2 absolute. Add your tyre pressure to > that for the total absolute pressure. > Absolute zero temperature is -460 deg F. Temperature from absolute zero is > designated degrees Kelvin (Scottish physicist - I first met TCs in the > Kelvinside area of Glasgow). 32 degF is 492 degK. > > For tyres at approximately the maker's recommended pressure, variations in > pressure in average driving will not have much effect on the TOTAL volume > of > gas in the tyre. Then V is almost constant, so that for most purposes P/T > is > constant. Heat the gas (any gas - helium through argon) by 50 F degrees (K > degrees) or 10%, and the absolute pressure will also increase by 10%. > > > > Nitrogen has a molecular weight (MW) of 28. Air has a MW of 28.966. There > is > next to no difference in the ratios of their specific heats. The mass of > air > or nitrogen in a given volume at a given pressure will be within 3%. > The average commercial tyre pressure gauge is probably about that > accurate. > > This worked pretty well when I was at school, and for the 25 years that I > have been selling gas handling equipment. > > > Regards, > > Robin Montgomery > _________________________________ > > -----Original Message----- > From: 1939mgtb [mailto:1939mgtb@comcast.net] > Sent: Thursday, September 29, 2005 9:04 AM > To: mg-tabc@yahoogroups.com; Robin Montgomery > Subject: Re: [mg-tabc] Tire aging bombshell could cause harm > > only not as fast or as radically.....since air is only 80% N. the other > components of air expand at a far higher rate. such as the 14% O2. > and that is why we use nitrogen in high speed aircraft tires. > Best, > Ray > "Spes mea in Deo est" > ----- Original Message ----- > From: "Robin Montgomery" RMontgomery@doriandrake.com> > To: mg-tabc@yahoogroups.com> > Sent: Wednesday, September 28, 2005 11:56 PM > Subject: RE: [mg-tabc] Tire aging bombshell could cause harm > > >> Nitrogen - as a gas - will expand with increasing temperature and its >> behaviour is subject to exactly the same laws of physics as air, of which >> it >> is a major component. >> >> >> Regards, >> >> Robin Montgomery >> _________________________________ >> >> -----Original Message----- >> From: mg-tabc@yahoogroups.com [mailto:mg-tabc@yahoogroups.com] On Behalf >> Of >> sara e jenkins >> Sent: Wednesday, September 28, 2005 4:07 PM >> To: artfitz@sympatico.ca; paroor@t-online.de; 1939mgtb@comcast.net; >> mg-tabc@yahoogroups.com >> Subject: RE: [mg-tabc] Tire aging bombshell could cause harm >> >> the most common reson to use nitrogen to fill tires is to provide >> extreramly >> accurate milage measurements for rallies-unlike air the nitrogen doesn't >> expand and contract with temperature so the tire size stays constant-i >> have >> never known of an old tire exploding-and i am talking about vintage car >> rallies-as the resuly of nitrogen. >> >> >> >> >> >> >> Yahoo! Groups Links >> >> >> >> >> >> > > > > > > Yahoo! Groups Links > > > > > >

[candahill@worldnet.att.net]

Robin, unless I've misunderstood what I've been told, the problem is the vapor pressure of moisture in the air. What does that do to your gas equations? Charles Hill -------------- Original message from "Robin Montgomery" RMontgomery@doriandrake.com>: --------------

> The wizardry is in either the design of tyres or the attention given to them > when under study. > > The Universal Gas Law applies to all gases (but not to vapors in mixed gas / > liquid phases - as propane in a pressurised tank) and is - > > Pressure (absolute) x Volume, divided by Temperature (absolute) is constant > for a given gas or gas mixture. (P.V/T = Constant) > > > Atmospheric pressure is 14.7 lbs/in2 absolute. Add your tyre pressure to > that for the total absolute pressure. > Absolute zero temperature is -460 deg F. Temperature from absolute zero is > designated degrees Kelvin (Scottish physicist - I first met TCs in the > Kelvinside area of Glasgow). 32 degF is 492 degK. > > For tyres at approximately the maker's recommended pressure, variations in > pressure in average driving will not have much effect on the TOTAL volume of > gas in the tyre. Then V is almost constant, so that for most purposes P/T is > constant. Heat the gas (any gas - helium through argon) by 50 F degrees (K > degrees) or 10%, and the absolute pressure will also increase by 10%. > > > > Nitrogen has a molecular weight (MW) of 28. Air has a MW of 28.966. There is > next to no difference in the ratios of their specific heats. The mass of air > or nitrogen in a given volume at a given pressure will be within 3%. > The average commercial tyre pressure gauge is probably about that accurate. > > This worked pretty well when I was at school, and for the 25 years that I > have been selling gas handling equipment. > > > Regards, > > Robin Montgomery > _________________________________ > > -----Original Message----- > From: 1939mgtb [mailto:1939mgtb@comcast.net] > Sent: Thursday, September 29, 2005 9:04 AM > To: mg-tabc@yahoogroups.com; Robin Montgomery > Subject: Re: [mg-tabc] Tire aging bombshell could cause harm > > only not as fast or as radically.....since air is only 80% N. the other > components of air expand at a far higher rate. such as the 14% O2. > and that is why we use nitrogen in high speed aircraft tires. > Best, > Ray > "Spes mea in Deo est" > ----- Original Message ----- > From: "Robin Montgomery" > To: > Sent: Wednesday, September 28, 2005 11:56 PM > Subject: RE: [mg-tabc] Tire aging bombshell could cause harm > > > > Nitrogen - as a gas - will expand with increasing temperature and its > > behaviour is subject to exactly the same laws of physics as air, of which > > it > > is a major component. > > > > > > Regards, > > > > Robin Montgomery > > _________________________________ > > > > -----Original Message----- > > From: mg-tabc@yahoogroups.com [mailto:mg-tabc@yahoogroups.com] On Behalf > > Of > > sara e jenkins > > Sent: Wednesday, September 28, 2005 4:07 PM > > To: artfitz@sympatico.ca; paroor@t-online.de; 1939mgtb@comcast.net; > > mg-tabc@yahoogroups.com > > Subject: RE: [mg-tabc] Tire aging bombshell could cause harm > > > > the most common reson to use nitrogen to fill tires is to provide > > extreramly > > accurate milage measurements for rallies-unlike air the nitrogen doesn't > > expand and contract with temperature so the tire size stays constant-i > > have > > never known of an old tire exploding-and i am talking about vintage car > > rallies-as the resuly of nitrogen. > > > > > > > > > > > > > > Yahoo! Groups Links > > > > > > > > > > > > > > > > > > Yahoo! Groups Links > > > > > >

[Non-text portions of this message have been removed]

[Robin Montgomery]

Charles, Slow reply. I was in India last week - end of the monsoon, and about as much vapor pressure of water as one can want - and have spent this week trying to find the surface of my desk. Water vapor behaves just like any other gas in the range of temperatures and pressure which concern us - e.g so long as it is vapor and does not liquify (or freeze). There is a possibility of having water condense out of pressurised air in a tyre if the local humidity is high and one uses a pump to inflate the tyre directly. It is unlikely if you inflate the tyre from a compressor with an air receiver tank, because any condensation will occur as the air cools in the tank (which should be fitted with a drain tap). One would also need to fill the tyre up from empty with high humidity air; just topping up the pressure would not do it. Now our ancestors were far more likely to use a foot or hand pump, and to use it to inflate an inner tube from empty - so maybe, under the right/ wrong conditions, they did get liquid water condensing in their tyres. When that liquid water heated and vaporised it would, indeed, cause excess pressure in the tyre. Nitrogen generation would be subject to tight quality controls, and water would be frozen out in storage. "Shop" air in a centralised compressed air system should be dried down to a very low dew point (in a chiller or desiccany drier) because pneumatic tools and other devices prefer dry air. Furthermore, if the pipework is not properly installed water can condense and accumulate at low points, and slugs of water could be sent to equipment that cannot tolerate it. It seems that you hit on the original reason for using nitrogen - thanks. Nitrogen is probably the easiest bottled gas to create - after air. Regards, Robin Montgomery _________________________________ -----Original Message----- From: mg-tabc@yahoogroups.com [mailto:mg-tabc@yahoogroups.com] On Behalf Of candahill@worldnet.att.net Sent: Thursday, September 29, 2005 3:04 PM To: mg-tabc@yahoogroups.com Subject: RE: [mg-tabc] Tire aging bombshell could cause harm Robin, unless I've misunderstood what I've been told, the problem is the vapor pressure of moisture in the air. What does that do to your gas equations? Charles Hill -------------- Original message from "Robin Montgomery" RMontgomery@doriandrake.com>: --------------

> The wizardry is in either the design of tyres or the attention given > to them when under study. > > The Universal Gas Law applies to all gases (but not to vapors in mixed > gas / liquid phases - as propane in a pressurised tank) and is - > > Pressure (absolute) x Volume, divided by Temperature (absolute) is > constant for a given gas or gas mixture. (P.V/T = Constant) > > > Atmospheric pressure is 14.7 lbs/in2 absolute. Add your tyre pressure > to that for the total absolute pressure. > Absolute zero temperature is -460 deg F. Temperature from absolute > zero is designated degrees Kelvin (Scottish physicist - I first met > TCs in the Kelvinside area of Glasgow). 32 degF is 492 degK. > > For tyres at approximately the maker's recommended pressure, > variations in pressure in average driving will not have much effect on > the TOTAL volume of gas in the tyre. Then V is almost constant, so > that for most purposes P/T is constant. Heat the gas (any gas - helium > through argon) by 50 F degrees (K > degrees) or 10%, and the absolute pressure will also increase by 10%. > > > > Nitrogen has a molecular weight (MW) of 28. Air has a MW of 28.966. > There is next to no difference in the ratios of their specific heats. > The mass of air or nitrogen in a given volume at a given pressure will be

within 3%.

> The average commercial tyre pressure gauge is probably about that

accurate.

> > This worked pretty well when I was at school, and for the 25 years > that I have been selling gas handling equipment. > > > Regards, > > Robin Montgomery > _________________________________ > > -----Original Message----- > From: 1939mgtb [mailto:1939mgtb@comcast.net] > Sent: Thursday, September 29, 2005 9:04 AM > To: mg-tabc@yahoogroups.com; Robin Montgomery > Subject: Re: [mg-tabc] Tire aging bombshell could cause harm > > only not as fast or as radically.....since air is only 80% N. the > other components of air expand at a far higher rate. such as the 14% O2. > and that is why we use nitrogen in high speed aircraft tires. > Best, > Ray > "Spes mea in Deo est" > ----- Original Message ----- > From: "Robin Montgomery" > To: > Sent: Wednesday, September 28, 2005 11:56 PM > Subject: RE: [mg-tabc] Tire aging bombshell could cause harm > > > > Nitrogen - as a gas - will expand with increasing temperature and > > its behaviour is subject to exactly the same laws of physics as air, > > of which it is a major component. > > > > > > Regards, > > > > Robin Montgomery > > _________________________________ > > > > -----Original Message----- > > From: mg-tabc@yahoogroups.com [mailto:mg-tabc@yahoogroups.com] On > > Behalf Of sara e jenkins > > Sent: Wednesday, September 28, 2005 4:07 PM > > To: artfitz@sympatico.ca; paroor@t-online.de; 1939mgtb@comcast.net; > > mg-tabc@yahoogroups.com > > Subject: RE: [mg-tabc] Tire aging bombshell could cause harm > > > > the most common reson to use nitrogen to fill tires is to provide > > extreramly accurate milage measurements for rallies-unlike air the > > nitrogen doesn't expand and contract with temperature so the tire > > size stays constant-i have never known of an old tire exploding-and > > i am talking about vintage car rallies-as the resuly of nitrogen. > > > > > > > > > > > > > > Yahoo! Groups Links > > > > > > > > > > > > > > > > > > Yahoo! Groups Links > > > > > >

[Non-text portions of this message have been removed] Yahoo! Groups Links

[DOUGLAS CROFT]

Robin, Yes water in the gaseous phase behaves as all gases however the boiling point of water is 373degrees K(100C) and I am sure that tyres are cooler than that. Assuming the air in the tyre is contaminated by water vapour then changes in temperature will mean changes in the ability of the air to absorb water vapour which is not a gas. Such phenomena as partial pressures etc. come into the equation. Dry air will behave in a similar manner to dry nitrogen. Doug tc1331 Robin Montgomery RMontgomery@doriandrake.com> wrote: Charles, Slow reply. I was in India last week - end of the monsoon, and about as much vapor pressure of water as one can want - and have spent this week trying to find the surface of my desk. Water vapor behaves just like any other gas in the range of temperatures and pressure which concern us - e.g so long as it is vapor and does not liquify (or freeze). There is a possibility of having water condense out of pressurised air in a tyre if the local humidity is high and one uses a pump to inflate the tyre directly. It is unlikely if you inflate the tyre from a compressor with an air receiver tank, because any condensation will occur as the air cools in the tank (which should be fitted with a drain tap). One would also need to fill the tyre up from empty with high humidity air; just topping up the pressure would not do it. Now our ancestors were far more likely to use a foot or hand pump, and to use it to inflate an inner tube from empty - so maybe, under the right/ wrong conditions, they did get liquid water condensing in their tyres. When that liquid water heated and vaporised it would, indeed, cause excess pressure in the tyre. Nitrogen generation would be subject to tight quality controls, and water would be frozen out in storage. "Shop" air in a centralised compressed air system should be dried down to a very low dew point (in a chiller or desiccany drier) because pneumatic tools and other devices prefer dry air. Furthermore, if the pipework is not properly installed water can condense and accumulate at low points, and slugs of water could be sent to equipment that cannot tolerate it. It seems that you hit on the original reason for using nitrogen - thanks. Nitrogen is probably the easiest bottled gas to create - after air. Regards, Robin Montgomery _________________________________ -----Original Message----- From: mg-tabc@yahoogroups.com [mailto:mg-tabc@yahoogroups.com] On Behalf Of candahill@worldnet.att.net Sent: Thursday, September 29, 2005 3:04 PM To: mg-tabc@yahoogroups.com Subject: RE: [mg-tabc] Tire aging bombshell could cause harm Robin, unless I've misunderstood what I've been told, the problem is the vapor pressure of moisture in the air. What does that do to your gas equations? Charles Hill -------------- Original message from "Robin Montgomery" : --------------

> The wizardry is in either the design of tyres or the attention given > to them when under study. > > The Universal Gas Law applies to all gases (but not to vapors in mixed > gas / liquid phases - as propane in a pressurised tank) and is - > > Pressure (absolute) x Volume, divided by Temperature (absolute) is > constant for a given gas or gas mixture. (P.V/T = Constant) > > > Atmospheric pressure is 14.7 lbs/in2 absolute. Add your tyre pressure > to that for the total absolute pressure. > Absolute zero temperature is -460 deg F. Temperature from absolute > zero is designated degrees Kelvin (Scottish physicist - I first met > TCs in the Kelvinside area of Glasgow). 32 degF is 492 degK. > > For tyres at approximately the maker's recommended pressure, > variations in pressure in average driving will not have much effect on > the TOTAL volume of gas in the tyre. Then V is almost constant, so > that for most purposes P/T is constant. Heat the gas (any gas - helium > through argon) by 50 F degrees (K > degrees) or 10%, and the absolute pressure will also increase by 10%. > > > > Nitrogen has a molecular weight (MW) of 28. Air has a MW of 28.966. > There is next to no difference in the ratios of their specific heats. > The mass of air or nitrogen in a given volume at a given pressure will be

within 3%.

> The average commercial tyre pressure gauge is probably about that

accurate.

> > This worked pretty well when I was at school, and for the 25 years > that I have been selling gas handling equipment. > > > Regards, > > Robin Montgomery > _________________________________ > > -----Original Message----- > From: 1939mgtb [mailto:1939mgtb@comcast.net] > Sent: Thursday, September 29, 2005 9:04 AM > To: mg-tabc@yahoogroups.com; Robin Montgomery > Subject: Re: [mg-tabc] Tire aging bombshell could cause harm > > only not as fast or as radically.....since air is only 80% N. the > other components of air expand at a far higher rate. such as the 14% O2. > and that is why we use nitrogen in high speed aircraft tires. > Best, > Ray > "Spes mea in Deo est" > ----- Original Message ----- > From: "Robin Montgomery" > To: > Sent: Wednesday, September 28, 2005 11:56 PM > Subject: RE: [mg-tabc] Tire aging bombshell could cause harm > > > > Nitrogen - as a gas - will expand with increasing temperature and > > its behaviour is subject to exactly the same laws of physics as air, > > of which it is a major component. > > > > > > Regards, > > > > Robin Montgomery > > _________________________________ > > > > -----Original Message----- > > From: mg-tabc@yahoogroups.com [mailto:mg-tabc@yahoogroups.com] On > > Behalf Of sara e jenkins > > Sent: Wednesday, September 28, 2005 4:07 PM > > To: artfitz@sympatico.ca; paroor@t-online.de; 1939mgtb@comcast.net; > > mg-tabc@yahoogroups.com > > Subject: RE: [mg-tabc] Tire aging bombshell could cause harm > > > > the most common reson to use nitrogen to fill tires is to provide > > extreramly accurate milage measurements for rallies-unlike air the > > nitrogen doesn't expand and contract with temperature so the tire > > size stays constant-i have never known of an old tire exploding-and > > i am talking about vintage car rallies-as the resuly of nitrogen. > > > > > > > > > > > > > > Yahoo! Groups Links > > > > > > > > > > > > > > > > > > Yahoo! Groups Links > > > > > >

[Non-text portions of this message have been removed] Yahoo! Groups Links Yahoo! Groups Links [Non-text portions of this message have been removed]