Effects of high altitude
 

I just moved to a higher altitude place and my gas grill now burns a lot hotter (hot enough to make the bottom rack red hot). I'm curious if this is an effect of the high altitude or possibly the new briquetts i'm using.

How much higher are we talking? I wouldn't imagine it would make a fire burn hotter, because the higher up you go the less oxygen there is, so that doesn't seem like it would happen. I might be wrong though.

well i was at 1500 feet and now i'm at 4500. There is less oxygen but on a gas grill oxygen isn't what is burning it is the gas. I'm using propane also.

Oh contrare, it is actually a combustion reaction, what is happening is propane, C3H8 + O2 combining to form CO2 and H20. If you would like a (much) more detailed explanation of the reaction, PM me, I'm a pre-med student and have a TON of chem under my belt. As for the problem at hand, there is less pressure, therefore less oxygen, and finally, less combustion (this is assuming that there is a significant difference in partial pressures of oxygen between the aforementioned altitudes.) Anyway, I vote for the briquetes being the difference, or the move may have jostled the pressure regulator on your tank.

man my spelling sucks at midnight

Liquid propane does not contain an oxidizer. There is less oxygen available for burning.

It's probably the briquettes.

the only reason i don't really think it is the briquets is because the flames coming out of the gas area were much bigger than normal and the grate that got redhot was the one that the briquets sat on not above them.

it may be the regulator though, is that part of the grill or the propane tank?

I'll tell you this much, dont know much about the grill, but I get intoxicated much much faster and much easier thats what 5,000ft + do to me, less oxygen in the air

Yes, alchohol has a greater effect at higher altitudes. Gas also is much less efficient. Some cars will stall unless they are altered for the higher altitude. I would say that a hotter flame MUST be the briquettes because the flame would normally burn much lower.

the difference between atmospheric pressure and the propane tank pressure is greater at higher altitudes, for obvious reasons. so when you put that sucker on 'high', more gas can come out. so basically, if my theory is right, it burns hotter because you are using more propane. you will also run out faster.

actually, my theory probably only makes sense if you brought the propane tanks with you from lower elevations. i bet there's some regulation about how much pressure (gage) that you can inflate those tanks to...

You also may notice that water boils at a temp lower than 100 deg C.
You might want to start paying attention to the 'high altitude' directions on some baking products.

I once moved from Ft Lauderdale to Denver. I had to make adjustments in the kitchen.

I don't think this would make a difference. The regulator on the propane tank is set to let a certain amount of gas through per minute. The difference in atmospheric pressure between 1500 and 4500 ft is very little. It would probably have little influence. Besides the pressure in the gas line after the regulator is much higher than atmospheric pressure, so the difference would not influence how fast it came out.

I think its the briquets. As basmoq said, less oxygen at increased altitude will mean less combustion and thus less heat...

when i lived in colorado i noticed that cigarettes burned much faster. i don't know if it was the altitude or the dry air, no humidity.

It would be the lack of humidity, water doesn't lend itself towards combustion reactions...

Actually, I believe that all who posted about a pressure delta are mostly correct.

Recall that the pressure of propane gas is a function of the vapour pressure (which is a function of pressure and temperature). This said, the pressure of the propane being released from the cylinder is regulated by a diaphragm regulator which may allow more pressure at a greater altitude due to the lower external pressure.

Those who say that the ambient O2 is the limiting factor may also be correct (in theory) though I am not sold on this one. How do you think jet planes are able to be propelled at high altitudes? ;)

Yup - with just a glazing over of the possibilities, my vote is with the pressure difference between the propane in the cylinder and the ambient pressure.

i'd agree with sapper mostly due to his discription of the fire. for one reason or another, more gas is coming out.

when i went to macupichu the bus stopped about halfway up for people to buy coca leaves to combat the altitude sickness. i don´t know how sick you get cuz i didn´t wanna pass up the opportunity to chew on coca leaves. it seemed to work. maybe you could grow a coupla plants in the garden. then you probably won´t even be hungry enough to bother thinking about the grill.

I live at 3,700 meter (approx 12,000 feet). Fires don't burn as hot, because of lack of oxygen. Clothes and puddles dry faster from the lack of humidity. Most of the major fires we have here have been fed by combustible fuels.

It takes about 2 or 3 days to acclimatize and about 2 weeks to be able to do strenuous sports. Water boils at a lower temperature.

The climate here is desert-like. The sun pounds down and since there isn't much atmosphere it is easy to sunburn. At night it gets very cold.

As others have said, my guess is your new briquettes are very good.