# Could you put both Hydrogen and Helium gas in the same balloon envelope? **URL:** \ **Category:** Factual Questions\ **Created:** [May 1, 2003, 4:18am UTC](https://boards.straightdope.com/t/could-you-put-both-hydrogen-and-helium-gas-in-the-same-balloon-envelope/172315 "2003-05-01T04:18:28Z")\ **Posts on this page:** 12\ **Page:** 1
**Author:** ![Ranchoth](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/ranchoth/32/1066_2.png) [@Ranchoth](https://boards.straightdope.com/u/Ranchoth)\ **Post date:** [May 1, 2003, 4:18am UTC](https://boards.straightdope.com/t/could-you-put-both-hydrogen-and-helium-gas-in-the-same-balloon-envelope/172315/1 "2003-05-01T04:18:28Z")
…or would that screw things up, somehow? I was thinking that this might be a method of saving on Helium in a story I’m working on (i.e., “cutting” the Helium used to fill a Balloon/airship with some percentage of Hydrogen), but I’m not sure what the practical effects would be. I assume there’d be no chemical reaction, and I’d guess that the Hydrogen would float to the “top” of the Helium, like oil in a bowl of water. Can anyone fill me in on what other effects there might be from inflating a balloon like this, or even if someone’s actually _tried_ this before, like in the early days of powered flight? Well, thanks for your time, Ranchoth ---
**Author:** ![Desmostylus](https://avatars.discourse-cdn.com/v4/letter/d/c57346/32.png) [@Desmostylus](https://boards.straightdope.com/u/Desmostylus)\ **Post date:** [May 1, 2003, 4:42am UTC](https://boards.straightdope.com/t/could-you-put-both-hydrogen-and-helium-gas-in-the-same-balloon-envelope/172315/2 "2003-05-01T04:42:07Z")
A few points: 1. Helium doesn’t react with anything much. 2. The hydrogen won’t “float to the top”. The nitrogen in a balloon filled with air doesn’t float on top of the oxygen, either. 3. It will work, but why would you bother? If you’re going to put _any_ hydrogen in the balloon, you have to deal with effects of hydrogen. You may as well leave out the helium and completely fill it with hydrogen. ---
**Author:** ![glilly](https://avatars.discourse-cdn.com/v4/letter/g/48db29/32.png) [@glilly](https://boards.straightdope.com/u/glilly)\ **Post date:** [May 1, 2003, 2:29pm UTC](https://boards.straightdope.com/t/could-you-put-both-hydrogen-and-helium-gas-in-the-same-balloon-envelope/172315/3 "2003-05-01T14:29:40Z")
The lower explosive limit of hydrogen is 17%. If the mixture of H2 to HE is only 17%, any mixing of this combo with air will immediately result in a H2% lower than 17%, rendering it safe (from a fire standpoint). You probably could realistically have a higher H2 concentration and still have it not flammable once further diluted by air, but I can’t do the calcs right now. ---
**Author:** ![Chronos](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/chronos/32/134_2.png) [@Chronos](https://boards.straightdope.com/u/Chronos)\ **Post date:** [May 1, 2003, 5:05pm UTC](https://boards.straightdope.com/t/could-you-put-both-hydrogen-and-helium-gas-in-the-same-balloon-envelope/172315/4 "2003-05-01T17:05:25Z")
For that matter, you could realistically have an H[sub]2[/sub] concentration of 100%, and still be safe. The reason that hydrogen isn’t used in blimps is not because it’s dangerous, but because the public _thinks_ it’s dangerous. Everyone knows that the Hindenburg burned, but most folks don’t know that it wasn’t the hydrogen burning, it was the envelope, which was basically coated with rocket fuel. It would have been nearly as bad, had the gas been helium. So if you put any hydrogen at all into your balloon, folks would panic. But if you did it anyway, it would work just fine. ---
**Author:** ![andy\_fl](https://avatars.discourse-cdn.com/v4/letter/a/49beb7/32.png) [@andy\_fl](https://boards.straightdope.com/u/andy_fl)\ **Post date:** [May 1, 2003, 5:14pm UTC](https://boards.straightdope.com/t/could-you-put-both-hydrogen-and-helium-gas-in-the-same-balloon-envelope/172315/5 "2003-05-01T17:14:13Z")
No problems I see with that :). Hydrogen is a lot safer than the common person thinks. Yes it is explosive, but it is the most diffusive gas - so it diffuses out before u get any buildup. Agrees on CHronos on that. The only problem I can see is that Hydrogen will diffuse through the envelope faster than the Helium. ---
**Author:** ![scr4](https://avatars.discourse-cdn.com/v4/letter/s/59ef9b/32.png) [@scr4](https://boards.straightdope.com/u/scr4)\ **Post date:** [May 1, 2003, 5:25pm UTC](https://boards.straightdope.com/t/could-you-put-both-hydrogen-and-helium-gas-in-the-same-balloon-envelope/172315/6 "2003-05-01T17:25:01Z")
> [@](#): > > \*Originally posted by Chronos \* > **The reason that hydrogen isn’t used in blimps is not because it’s dangerous, but because the public _thinks_ it’s dangerous.** I think that’s going a bit far. Hydrogen is definitely a dangerous gas to handle. A tank of hydrogen may be as safe as a tank of propane, but they’re still a lot more dangerous than helium. Why else would scientific balloons use helium, when they use every other trick in the book to make them lighter and larger to reach higher altitudes? ---
**Author:** ![Sengkelat](https://avatars.discourse-cdn.com/v4/letter/s/e36b37/32.png) [@Sengkelat](https://boards.straightdope.com/u/Sengkelat)\ **Post date:** [May 1, 2003, 5:29pm UTC](https://boards.straightdope.com/t/could-you-put-both-hydrogen-and-helium-gas-in-the-same-balloon-envelope/172315/7 "2003-05-01T17:29:25Z")
Chronos or andy\_fl: Where can I get more information on that? I’m intrigued. I’ve heard stories of WWI (I think…) fighters attacking german blimps with tracer rounds, resulting in \>\>WHOOOFF!!\<\< no more blimp. Are those just fanciful stories? ---
**Author:** ![Ms.Reckon](https://avatars.discourse-cdn.com/v4/letter/m/8c91f0/32.png) [@Ms.Reckon](https://boards.straightdope.com/u/Ms.Reckon)\ **Post date:** [May 1, 2003, 5:29pm UTC](https://boards.straightdope.com/t/could-you-put-both-hydrogen-and-helium-gas-in-the-same-balloon-envelope/172315/8 "2003-05-01T17:29:48Z")
That sounds like a great idea to me. What would make it perfect is if there were some flame inhibitor that could also be added to disperse with the hydrogen. ---
**Author:** ![andy\_fl](https://avatars.discourse-cdn.com/v4/letter/a/49beb7/32.png) [@andy\_fl](https://boards.straightdope.com/u/andy_fl)\ **Post date:** [May 1, 2003, 6:40pm UTC](https://boards.straightdope.com/t/could-you-put-both-hydrogen-and-helium-gas-in-the-same-balloon-envelope/172315/9 "2003-05-01T18:40:06Z")
> [@](#): > > \*Originally posted by Sengkelat \* > \*\*Chronos or andy\_fl: Where can I get more information on that? I’m intrigued. \*\* Sengkelat - you may learn about Hydrogen Safety from the [National Hydrogen Association](http://www.hydrogenus.org/hhs_1.htm). Quote from there - "What is often not acknowledged about the Hindenburg tragedy is that because hydrogen dissipates quickly, no Hindenburg fatality was the result of a burn from hydrogen. " Also, I had a cite, where they did tests on Hydrogen and Gasoline Cars and proved that Hydrogen cars were less prone to fire damage - I can dig that up if you want. ---
**Author:** ![rsa](https://avatars.discourse-cdn.com/v4/letter/r/839c29/32.png) [@rsa](https://boards.straightdope.com/u/rsa)\ **Post date:** [May 1, 2003, 7:10pm UTC](https://boards.straightdope.com/t/could-you-put-both-hydrogen-and-helium-gas-in-the-same-balloon-envelope/172315/10 "2003-05-01T19:10:47Z")
I’m not disputing either **andy\_fl** or **Chronos** , but would just point out that just because there were no fatalities due to hydrogen burns, that does not imply that there was not any signifcant amount of hydrogen which burned. ---
**Author:** ![Yossarian](https://avatars.discourse-cdn.com/v4/letter/y/9de0a6/32.png) [@Yossarian](https://boards.straightdope.com/u/Yossarian)\ **Post date:** [May 1, 2003, 8:46pm UTC](https://boards.straightdope.com/t/could-you-put-both-hydrogen-and-helium-gas-in-the-same-balloon-envelope/172315/11 "2003-05-01T20:46:20Z")
Here’s an article on the Forensic Chemistry of the Hindenburg disaster–if you’ve got access to ScienceDirect. The Hindenburg tragedy revisited: the fatal flaw found A. Bain1 and Wm. D. Van Vorst2, \* 1 Hydrogen Programs, Kennedy Space Center, NASA, USA 2 Chemical Engineering Department, University of California, Los Angeles, CA, 90095-1592, USA International Journal of Hydrogen Energy Volume 24, Issue 5 , 1 May 1999 , Pages 399-403 [http://www.sciencedirect.com/science?\_ob=ArticleURL&\_udi=B6V3F-3WWKMBT-C&\_coverDate=05%2F01%2F1999&\_alid=89335497&\_rdoc=1&\_fmt=&\_orig=search&\_qd=1&\_cdi=5729&\_sort=d&view=c&\_acct=C000050221&\_version=1&\_urlVersion=0&\_userid=10&md5=60e60bc50caed8cd8409f0ee18571bca](http://www.sciencedirect.com/science?_ob=ArticleURL&_udi=B6V3F-3WWKMBT-C&_coverDate=05%2F01%2F1999&_alid=89335497&_rdoc=1&_fmt=&_orig=search&_qd=1&_cdi=5729&_sort=d&view=c&_acct=C000050221&_version=1&_urlVersion=0&_userid=10&md5=60e60bc50caed8cd8409f0ee18571bca) ---
**Author:** ![Skywatcher](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/skywatcher/32/254_2.png) [@Skywatcher](https://boards.straightdope.com/u/Skywatcher)\ **Post date:** [May 1, 2003, 9:00pm UTC](https://boards.straightdope.com/t/could-you-put-both-hydrogen-and-helium-gas-in-the-same-balloon-envelope/172315/12 "2003-05-01T21:00:17Z")
> [@](#): > > \*Originally posted by Sengkelat \* > \*\* I’ve heard stories of WWI (I think…) fighters attacking german blimps with tracer rounds, resulting in \>\>WHOOOFF!!\<\< no more blimp. Are those just fanciful stories? \*\* IIRC, tracer rounds - and incendiary rounds for that matter - use phosphorus which ignites when exposed to air. Seems to me that oridinary rounds would just punch holes in the envelope.