We are considering getting a three burner NC forge to replace an old McEnglevan forge in my HS shop. The old forge is almost 30 years old. It has never been able to get to a good forging temperature despite years of fiddling with the mix. My question is: We have to go to Propane. Our natural gas line into the school is too low of a pressure to run the NC forge, without installing an expensive booster pump. We can get a 100 lb Propane bottle and install it outside, piping the gas into the shop. We are trying to find out about how may hours we can expect to get out of this quantity of Propane. We will rarely use it to a welding heat. We just need to go from the present 1900 degree forge to 2100 degree forging heat.

I appreciate any comments and suggestions. Thanks.

The commercial forge makers should be able to tell you gas usage at given heats...at least, one would expect that info from a company who was in the business of fulltime forge building, i.e. Johnson, Mankel, NC, etc.

I can tell you that my homemade, blown twin-burner gets about 40 hours of time from a 100lb tank and it will not quite make welding temp; bright yellow, yes - but not full welding temp.

I think a big stationary tank is a better solution if you are piping from the outside as the fuel is generally much cheaper. I was given a 500 gallon tank several years ago and foolishly sold it to buy some other tools - should have hung on to the tank and saved up for the rest.

I get about 40 hours off of my 100lb tank using a VF twin burner at about 15-20psi. Only time I take it higher than that is for welding and it quickly gets backed down.

We cannot have more than a 100 lb tank. It will be located in an interior courtyard outside of my shop. It will be an exchange setup. They will not be able to drag the fill line through the school hallway. I am going to check into the possibility of getting two 100 lb tanks, manifold them together. That should help with pressure drop in the winter. I figure two tanks should last for a good part of the school year.

Just a thought. I have used 2 tanks for heating. Had a switch over manifold. One tank at a time. Keep an eye on the indicator and never run out of gas. 2 tanks manifolded toghter will run out toghter.
Ken

Better check with local inspectors, building, fire, etc. One reason you only see high-end commercial forges (like Johnson) is that they have the "UL" and other stickers. If you can find a blown forge you could stay with natural gas. That would save a lot of fuss and expense.

Grant he did say the pressure was too low for a NC. I remember at school (blown methane forges) low pressure caused a scramble to shut them down.
Ken

I haven't counted the hours on my single burner, atmospheric, forge yet. It will operate at about 6 psi for normal forging. It won't make weld heat at any pressure. A 30# tank will last me a long time. Not much problem with freeze ups. I guess that's because I usually shut down every few minutes to save gas while I stupidly fumble about my shop. Maybe the 110 f weather helps too. :)

Thanks for all of the information.

We would like to get away from the blower NG forges because of the noise involved, and the fact that it does not get hot enough. Does anyone know of a commercially made NG forge, 2 to 4 burner, with a blower, that will get to a good forging heat, and is not sounding like a jet plane?

Using Natural Gas definately would be the easier way to go. We already have the feed line and if we stay with NG, the bill is paid by the school general account(they heat the school with it) and not by our department budget(for Propane tanks).

I really want to replace the old McEnglevan furnace, but I have not found a suitable replacement. I even kicked around the idea of a coal forge, but got rejected because of the smell. All ideas are welcome. Thanks.

Charcoal? Fairly clean, little smell, very traditional. Expensive thou.

I don't know if it would work with NG but propane blown type "ribbon burner" forges are supposed to be both very efficient and fairly quiet. A lot of glass blowers use them, and there was an article in the Hammer's Blow a few years ago about them.

Perhaps have the gas co up the pressure. School I went to had 3 3 burner mankels set up to run on methane(landfill gas) First class at school. Stopped there a few mos ago.
Converted school to a resident program he had 2 running wasn't bad at all.
Ken

I looked into getting the pressure supply upped. It cannot happen. The forge is at the end of the line that feeds several hot water heaters, the kitchen and my foundry furnace. They will not put in a separate meter and regulator and run 150' of piping for a relatively small use. I believe that we have about 2-3psi of NG in the line.

Does anyone know of a small forge that will run on this pressure, with a booster fan, that will produce the forging heat and is not too loud? I have not found anything yet.

I looked into a NG booster pump, but they are expensive, and requires engineering work and a lot of complications. All of this might be a moot point, as the school is in a severe budget crunch. We might not have any funds for this project.

Sounds like you are back to running propane.

Since you are a school, talk to your gas supplier about a charitable donation of a bottle or two. They may bite on the basis of you will be buying fuel from them every few months.

Phil