mark
Frequent Poster
Posts: 203
From:
Registered: OCT 2000
posted 06-18-2001 12:59 PM
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I have a question: is MAP gas lighter than air? Not for floating balloons, but if i filled a paint can with the gas, and the paint can has a hole in the top and the bottom, which hole would the map gas leak out of?


ALENGOSVIG1
Moderator
Posts: 782
From: Canada
Registered: NOV 2000
posted 06-18-2001 01:43 PM
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Well, it is usually heavier than air depending on the concentration of the mixed gasses. For instance, i have a bottle of MAPP gas that is 66% methylacetylene. this is heavier then air.
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Explosives Archive



SafetyLast
Frequent Poster
Posts: 235
From: the cretaceous period
Registered: OCT 2000
posted 07-14-2001 04:49 PM
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Yes I have a couple bottles of compressed MAPP gas. the bottles themselves are yellow and the gas smells absolutely disgusting (like nauseating)
it is good for making fireballs with.
what else is it good for?


PHILOU Zrealone
Frequent Poster
Posts: 479
From: Brussels,Belgium,Europe
Registered: SEP 2000
posted 07-23-2001 08:18 AM
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Copper, silver and mercury acetylides!
BTW: CH3-C#C-H has a MM of 40g/mole while air is 4/5 of N2 28g/mole and 1/5 of O2 32g/mole.
So due to the laws of perfect gases: 1 mole of gas (any gas takes a volume of 22.41 liter at 20C (+/- 0.2 for very big molecules).
This means that even if air was pure O2 and has a density of 32g/22.41 l MA would be heavier about 1/4 heavier.

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Bitter
Frequent Poster
Posts: 292
From: 11 Downing Street, London, England
Registered: SEP 2000
posted 07-23-2001 02:28 PM
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Mapp gas was intended for welding and brazing on a very small scale where the costs would be cheaper than acetylene, yet the flame (when with oxygen) would be hotter than with propane.

I also own several MAPP gas cylinders, and I read on some internet source that MAPP gas burned hotter than acetylene. Is that true?

I don't know about that, acetylene burns very hot when mixed with oxygen. About 3300°C at the hottest part of the flame IIRC.

Propane - 2828°
MAPP - 2,927°
Acetylene - 3410°

You may think there isnt much difference, but that only tells part of the story, its the heat distribution within the flame that matters, at least for welding/cutting.

Not having access to Calcium Carbide (yet, at least) or straight Acetylene, which I intend to use for testing FAE mixtures, could I substitute with MAPP? That is, are Methyl Acetylene and Propadiene capable of detonating in proper concentrations with air, like Acetylene is? I have not seen any mention of either forming "explosive" air mixtures in their MSDS's, as I have with the MSDS of Acetylene...unless that little line has slipped my memory.

According to this site: http://www.tpub.com/steelworker1/34.htm MAPP gas has a low explosive concentration in air. I think that will ruin all your fun. If you did it in pure oxygen it goes much higher than the 10.8% possible in air. While it doesn't specifically say detonation or no detonation, I believe it may be possible if using oxygen. Using just air is a bit iffy.

Mixtures of methylacetylene and propadiene will form ultra strong FA mixtures with air.
Detonated in enclosed space they will have at least 3 times the destrctive effect of the equal mass TNT.

Due to Methyl Acetylene's rather narrow explosive limits in normal air, in comparison to its very wide limits in a pure Oxygen environment, I have a mildly innovative idea (something similar may have been suggested in the other FAE threads)... why not artificially enhance the amount of available Oxygen, by dispersing pure Oxygen gas with the MAPP or other fuel?? In this way, the fuel still relies on atmospheric Oxygen (thus the "Vacuum Bomb" effect), but the provided Oxygen boosts its performance and makes it more easily detonable. No, this won't expand the limits up to 80%...but even 30% or 40% will make things much easier.