Effect of ambient temperatures on forge?

[Xaraph]

I've set up my 2-burner gas forge in my backyard instead of my garage.  While it's nice for ventilation (and the view), I'm wondering how great an effect the ambient temps will have on reaching forge temperature. 

[timgunn1962]

Ambient temperature changes "should" directly affect the forge temperature by the same amount. Ambient drops X degrees, forge temp drops X degrees. Ambient rises Y degrees, forge temp rises Y degrees.

 

Breezes can affect the temperature, especially on Naturally Aspirated burners, by affecting the mixture. It's really a case of try it and see.

 

Biggest problem outside is likely to be the cylinder temperature dropping in cold weather and not supplying enough pressure. Big cylinders, a gentle heat source, or placing the cylinder in a tub of water can help. If you go for the tub of water, don't let it freeze with the cylinder still in.

[Neil Blythin]

I agree that tank / cylinder issues are the biggest consideration.  

 

I have my small gas forge set up in an unheated garage.  If its cold out, I can always turn up the pressure (temperature) on the forge a little.  But I run into issues with my propane tanks frosting up in the colder weather.  I'm using 40 lb tanks - which are just fine most of the year.  They only frost up when its at or below freezing outside.

[jcornell]

I have been forging outside in my back yard for more than three years now.  I find that having a cold anvil makes more of a difference than having a cold forge.  I cover everything up with plastic when it's cool, so it's just cold, not wet and cold.  I've forged down to freezing, but I usually wimp out and don't forge until it's above 35 degrees F.  At a certain point it's actually very comfortable to forge in the cold, as I don't have sweat dripping into my safety glasses.

[ciladog]

The real effect of ambient temperature on a forge, especially an aspirated forge, is not the temperature but the density of the air. Cold air is more dense than warm air and thus contains more oxygen for a given volume of air. The barometric pressure will also effect the operation of the forge.

While these effects are real (but slight) there is not much you can do about it so why be concerned?

[Xaraph]

Thanks guys, I had not considered the effects it could have on the propane cylinder.  This may solve the "thwoomping" problem I've been getting when firing things up. 

[brian robertson]

after4 decades of running a truck mounted forge, I think humidity has the biggest impact on forge perfomance. Altitude on venturi burners can be an issue but not so with a blower forge.

[Zengineer]

Mostly covered already, but to expand on a couple points:

 

Altitude: atmospheric burners only. You will see a huge effect on burn quality with changes in altitude. In the gas fireplace industry you changed your gas orifice size based on altitude to compensate for less oxygen in a given volume of air.

 

Temperature: Colder air is more dense, and contains more oxygen. Hot air, the opposite. Air temperature will effect your burn quality (ie: change the mixture), and as a result the overall forge temperature. It won't just offset the forge temperature by the differential temperature between the two environments you are comparing.

 

Good note above on cylinder temperature being a concern in colder temps, especially if you are pushing the limites of your cylinder.

 

I'd like to hear more about the noticable effects of humidity on the forge performance.