We are building a forge to use at school. Have concidered the pros and cons of coal and gas. we dont want to cut any holes in the building for hoods and with winter coming on cant really see forging out side much. we have natural gas plumbed in for the heaters and could split off from that line for a couple of forges. Any ideas on LPG over Nat gas? Any advice or comments would be welcomed.

I think I would be venting any forge. They put out lots of nasty gases and you don't want a room full of students in the same room with no ventillation.

i don't think you will have enough nat gas pressure out of a city line to do any good- but i could be wrong.

Natural Gas should be ok if you build a blown type of burner. The only problem with natural gas is the pressure it comes in at being too low to naturally aspirate if I understand the process correctly.

You will have to vent the forge or some one, perhaps several someones, may die. These forges burn a lot more gas than a heater and usually even the heaters are vented.

if i had a choice i would use lpg i used a natural gas furnace in high school and my shop teacher didn't really like it (the shop origanly had a coal forge in it and state made the school remove it ) it took alot of time to get things up to temps for forging if i remember right it requierd like 2" main for the gas and you would need a hood for the amount of gas you would be burning if you think about it all comercial kichtens have to have hoods for ventalation and i think the forge would use more gas then a stove or grill

Thanks guys for your input. brought to light some other thoughts.
Dave

Can run the natural gas forges, but need to ask to have the gas pressure in the line raised by the gas company. Doesn't have anywhere near the force pressure needed for a forge to run normally. And must of course have all the safeties in place like any other gas appliance, which takes it out of the range of a home build forge. Venting is an absolute must, even if it's a side draft through the wall. It's been done here before.. might take a bit of searching to find it though.

Must be vented either way but nat gas is usually cheaper. Get in touch with the supplier and get a larger reg for a specifed Btu range. The gas line on the other side of the reg or meter set is usually more than you need. Two meter sets , one for household and one industrial.

iive used a natural gas forge ... worked fine if you can get the pressure bumped up for a forge ide use it .. alot cheaper to run . if you use propane get a BIG tank and have a truck fill it rather than smaller bottles and takeing them in. for a forced air forge there isnt much difference heat wise ... unless your planning on doing a lot of forge welding. good luck!

if your building it for a school.. just make it temporary, so you can kick it under an arc' fume hood.. flip it on, and use your propane, or nat forge..

you could use coal outside too..depending on where you live

Loken Forge in Omaha, NE uses house pressure natural gas in their forges (.5 water column) or something like that. They are full time blacksmiths doing high end ironwork. They run 2 or 3 of these blacksmith forges. They do all kinds of large 2" bar and smaller forging. They just run the natural gas from a 1/2" iron pipe. No restrictions of any type. The glass blowing shop in the same building uses the same natural gas and same pressure for their glass forges. I don't think they forge weld in them, but I'm not sure. Call them up if you would like more information.

I run natural gas at 5 lb. pressure in a blown forge. It cost me approx. $200 to get the pressure pumped up here in the city. I can easily max out my pyrometer at 2500 degrees F. Next time I'll just use regular city pressure as I know it works.

I gotta agree with blksmith. I've run natural gas for 30+ years, both high pressure (15psi) and low pressure (residetial pressure). I ran a pretty big slot forge on the low pressure with just 3/4 inch pipe.

Grant