# Are inert gases less effected by changes in pressure? **URL:** \ **Category:** Factual Questions\ **Created:** [October 29, 2019, 10:44pm UTC](https://boards.straightdope.com/t/are-inert-gases-less-effected-by-changes-in-pressure/842676 "2019-10-29T22:44:15Z")\ **Posts on this page:** 8\ **Page:** 2
**Author:** ![Andy\_L](https://avatars.discourse-cdn.com/v4/letter/a/c67d28/32.png) [@Andy\_L](https://boards.straightdope.com/u/Andy_L)\ **Post date:** [October 30, 2019, 4:12pm UTC](https://boards.straightdope.com/t/are-inert-gases-less-effected-by-changes-in-pressure/842676/21 "2019-10-30T16:12:32Z")
> [@am77494](#): > > I am not sure, I understand your post. In the OP’s context, the deviations from ideal gas laws have nothing to do with tire fires. Also smaller molecule gases like Helium, although inert, will be the worst gas to inflate tires since it will escape. > > In the OP’s context, the use of inert gas is to avoid the presence of oxygen. And btw Nitrogen is not a inert gas but close enough for the OP’s context. I think we’re saying the same thing. While inert gases deviate less from the ideal gas law than other gases, this can’t have anything to do with what the OP heard - what the OP heard is more likely to involve the use of nitrogen to avoid oxygen, rather than any inert quality of nitrogen itself. ---
**Author:** ![Derleth](https://avatars.discourse-cdn.com/v4/letter/d/b9e5f3/32.png) [@Derleth](https://boards.straightdope.com/u/Derleth)\ **Post date:** [October 30, 2019, 5:45pm UTC](https://boards.straightdope.com/t/are-inert-gases-less-effected-by-changes-in-pressure/842676/22 "2019-10-30T17:45:26Z")
> [@am77494](#): > > Maybe all the above will get accepted as normal usage with time. Like momentarily did. > [@EdelweissPirate](#): > > (Costco doesn’t charge extra, which is nice) Another example of rampant linguistic drift! Soon, we’ll only have about half as many girls running around. ---
**Author:** ![EdelweissPirate](https://avatars.discourse-cdn.com/v4/letter/e/8491ac/32.png) [@EdelweissPirate](https://boards.straightdope.com/u/EdelweissPirate)\ **Post date:** [October 30, 2019, 11:41pm UTC](https://boards.straightdope.com/t/are-inert-gases-less-effected-by-changes-in-pressure/842676/23 "2019-10-30T23:41:03Z")
> [@am77494](#): > > […] so the pressure change in the tire due to water is **negligible**. It’s always nice when people show their work! I mean that sincerely; nice post! Two points of clarification: - Most of the concern about water revolves around the liquid kind turning to steam. AFAIK, this is really only a practical concern in race car tires; 200 PSIG aircraft tires probably don’t get hot enough to boil water at that pressure very often. - Condensation isn’t the main source of water in tires. That would be compressors, which accumulate it. Almost any compressor not rigorously maintained will eventually start sending slugs of liquid water down the air line. I used to work on radiation oncology treatment systems that required an air compressor. It’s hard to get a dew point below -40 degrees with cooling alone…if you want drier air than that, you’ll need a self-regenerating desiccant system downstream of the refrigeration dryer. We had both, and we’d still get liquid water from compressors occasionally. Water condensed from humid air isn’t great, but there are bigger and wetter problems with compressed air. Generating truly dry air on location is expensive and requires rigorous maintenance. In that context, it’s pretty convenient to just buy a tank of nitrogen. ---
**Author:** ![HMS\_Irruncible](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/hms_irruncible/32/7394_2.png) [@HMS\_Irruncible](https://boards.straightdope.com/u/HMS_Irruncible)\ **Post date:** [October 30, 2019, 11:49pm UTC](https://boards.straightdope.com/t/are-inert-gases-less-effected-by-changes-in-pressure/842676/24 "2019-10-30T23:49:00Z")
> [@am77494](#): > > Nitrogen on the other hand is mostly made by cryogenic processes and is transported as liquid nitrogen and subsequently sold in cylinders at high pressure. Water is removed before the cryogenic liquefaction using mol-sieves which brings the dew point of Nitrogen to less than -70F. So the tires inflated with Nitrogen do not have the drawback of water condensation. If water is the culprit, why not use a similarly cryogenically processed air? I’d think it would be cheaper. I can’t help but think that part of this “less reactive” thing has to do with preventing parts from being oxidized or corroded over time (of which fire hazard is a specifically dramatic case). ---
**Author:** ![EdelweissPirate](https://avatars.discourse-cdn.com/v4/letter/e/8491ac/32.png) [@EdelweissPirate](https://boards.straightdope.com/u/EdelweissPirate)\ **Post date:** [October 31, 2019, 12:00am UTC](https://boards.straightdope.com/t/are-inert-gases-less-effected-by-changes-in-pressure/842676/25 "2019-10-31T00:00:47Z")
Why would that be cheaper? From an earlier post of AM’s, I gather that dry nitrogen is left over after you’re done making liquid oxygen. Why would it be cheaper to leave the oxygen in when you could sell it instead? ---
**Author:** ![am77494](https://avatars.discourse-cdn.com/v4/letter/a/d2c977/32.png) [@am77494](https://boards.straightdope.com/u/am77494)\ **Post date:** [October 31, 2019, 12:30am UTC](https://boards.straightdope.com/t/are-inert-gases-less-effected-by-changes-in-pressure/842676/26 "2019-10-31T00:30:26Z")
> [@HMS\_Irruncible](#): > > If water is the culprit, why not use a similarly cryogenically processed air? I’d think it would be cheaper. What EdelweissPirate said. Also cryogenic processes don’t produce dry products BUT they need dry air to start with. So the air is first dried using desiccants (mol-drives). If you don’t dry the air first, water will freeze all over the place and clog everything up. Also Oxygen is a feedstock in the Chemicals industry. It is used in the production of steel (Bessemer’s furnace) and certain bulk chemicals like Carbon Monoxide (used in turn to make acetic acid which is used to make fibers like rayon), methanol, etc. This leaves a lot of Nitrogen on the table which can be used either to cool the incoming air or sold to the market. Also like EdelweissPirate said, it is a headache to maintain a small desiccant system for small air compressors. Also note that most small compressors are not oil free, so the discharge carries oil with it and fouls up the system. It just works out cheaper to buy nitrogen cylinders and make a header system for use. If you need large quantities of nitrogen or high pressure , they will rent you a vaporizer and a small liquid nitrogen tank that they will fill up whenever you need. Also it takes less power to pump liquid nitrogen to a high pressure and then vaporize it to gas, than to compressor gaseous nitrogen. ---
**Author:** ![HMS\_Irruncible](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/hms_irruncible/32/7394_2.png) [@HMS\_Irruncible](https://boards.straightdope.com/u/HMS_Irruncible)\ **Post date:** [October 31, 2019, 1:03am UTC](https://boards.straightdope.com/t/are-inert-gases-less-effected-by-changes-in-pressure/842676/27 "2019-10-31T01:03:10Z")
> [@EdelweissPirate](#): > > Why would that be cheaper? From an earlier post of AM’s, I gather that dry nitrogen is left over after you’re done making liquid oxygen. Why would it be cheaper to leave the oxygen in when you could sell it instead? I dunno. I just say stuff sometimes. ---
**Author:** ![EdelweissPirate](https://avatars.discourse-cdn.com/v4/letter/e/8491ac/32.png) [@EdelweissPirate](https://boards.straightdope.com/u/EdelweissPirate)\ **Post date:** [October 31, 2019, 1:15am UTC](https://boards.straightdope.com/t/are-inert-gases-less-effected-by-changes-in-pressure/842676/28 "2019-10-31T01:15:00Z")
Oh, I hope I didn’t come off as dismissive. I thought I might be missing something. And I just say stuff sometimes too, so cheers. [Previous page](https://boards.straightdope.com/t/are-inert-gases-less-effected-by-changes-in-pressure/842676.md?page=1)