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Low humidity vs. high humidity nitro exhaust (1 Viewer)

flapjack

Staff member
Nitro Member
Some of you may already know that nitro exhaust burns because it contains nitric acid. That from incomplete combustion byproducts bonding with water. I’m guessing the higher the humidity, the exhaust gets more irritating because there’s more water to bind to. Has anyone in this forum noticed a difference in the exhaust between high humidity and low humidity races?
 

flapjack

Staff member
Nitro Member
I thought Nitric Acid was the byproduct of the combustion.
NOx is a byproduct of incomplete combustion of some of the nitro, which then mixes with the water in the air to form nitric acid. I am not sure if that happens in the combustion chamber or as the exhaust leaves the combustion chamber...
 

vegasnitro

Nitro Member
Nitromethane does not contain nitric acid, nitro methane's chemical formula is CH3NO2. Nitric acid is a byproduct of combustion, it's chemical formula is HNO3. Water (H2O) and Carbon Dioxide (CO2) are also produced, along with a bunch of other compounds when mixed with methanol like racing nitro is.

So now to the original question. Does nitro burn your eyes more on humid days versus dry days? There is obviously going to be more water vapor in the air and therefor more Hydrogen and Oxygen for the Nitrogen to bond to during the combustion process in high humidity areas. The air that we breathe, the Earth's atmosphere, is also between 67-70% Nitrogen, which would lead to more Nitrogen bonding with more Hydrogen and Oxygen during combustion in high humidity areas. Without getting a chemical engineer involved, I am going to say YES, there will be more nitric acid produced at St Louis or Atlanta than there will be at Vegas or Phoenix. Is it a lot more? Probably not, but more is more, so it will be more of an irritant.
 
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mick

Nitro Member
this is a good thread. interesting question that involves a little science and investigating. yesterday i spent a ridiculous amount of time trying to educate myself on topics surrounding
the initial question regarding nitro fumes and varied humidity levels. thanks for the response chris cook; i'm on board with your explanation
 

TSK

Staff member
Nitro Member
You know, the only way to quantify this is to have somebody stand in the exhaust cloud of a nitro warm-up in Gainesville, then again at Vegas and see how long they can stand there before needing get into fresh air.
If somebody would pay my way, I'd do it!
 

1963grinch

Nitro Member
I help out on a nitro fc team and I can tell you that the fumes have have been much worse at the 2 Indys so far than it was in either Pomona or Phx. This doesn't prove the humidity theory but the humidity was high at both Indys. The fumes were so bad one time that even the tuner/driver was driven away to get his gas mask. He's been at it 20 plus years.
 
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