Propane efficiency?

A

AlaskanHunter

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Nov 23, 2013
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Do any of you have any idea how many hours a medium sized forge will run on a tank of propane (and what size of tank)? I realize that there are a lot of factors that go into fuel consumption, so I'm assuming a welding heat and slightly reducing. Also, does a blown vs venturi burner make a significant difference?
I've been using a waste oil forge and charcoal forges so far, but both leave a bit to be desired when fine control is needed. However, $8.50 a gallon for propane (down from $13.25 last year) is a rather painful price. I'm trying to decide whether it's worth it for me to choke up the money to build a propane setup to supplement my current forges.
 
Holly crap! 8.50$ a gallon?!!! I'd go broke trying to run my forges at that price. Down here it's running 2.60$ a gallon. One of the things I did was to put in a 250 gallon tank and have it delivered. I try and fill it up when they have the summer special.

What about natural gas? Is that available to you? I've never run a forge on it, but have heard of people doing so. At that price I'd stick to charcoal and coal.

The words efficiency and propane forge should not be used in the same sentence. That said, I've heard people getting pretty efficient with a ribbon burner. One of these days I'd love to try one.
 
Will52100 said:
Holly crap! 8.50$ a gallon?!!! I'd go broke trying to run my forges at that price. Down here it's running 2.60$ a gallon. One of the things I did was to put in a 250 gallon tank and have it delivered. I try and fill it up when they have the summer special.

What about natural gas? Is that available to you? I've never run a forge on it, but have heard of people doing so. At that price I'd stick to charcoal and coal.

The words efficiency and propane forge should not be used in the same sentence. That said, I've heard people getting pretty efficient with a ribbon burner. One of these days I'd love to try one.
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Everything is expensive where I live. I guess that's the price of living in a fly in only village in one of the most beautiful parts of Alaska. Neither coal or natural gas are available here. I make my own charcoal because that's quite pricey to buy and ship in (anything non-hazmat costs between $.50- $1.00 per pound shipping). Since making it is quite tedious, I primarily use the waste oil forge.
 
Seems like waste oil is the way to go, "IF" you can get it working good. With a propane I'd think a forge is going to use at least 1 gallon per hour. I doubt there's really much difference in a venturi vs blown forge, provided each is setup properly. There's only so many BTU of heat in a gallon of propane.

As you said, just the price of living in paradise {g}
 
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K Ken H> You're probably right about my needing to try to get my oil forge running better, however I've been fighting several issues with it.
1. It takes 20 minutes to get running smoothly. I have to slowly bring up the temp, once the refractory hits 1400*F or so, it runs great, but until then its quite finicky and extremely smoky.
2. During start up and throughout its runtime, it's prone to 'woofing'. Not particularly dangerous, but I can't turn my back on it even for a few seconds. If it starts to 'woof' I hit an emergency shutoff valve to the fuel.
3. Because of 1 & 2, I have to operate it outdoors. Not fun in inclement weather, particularly sub-zero temps or wind.
4. Probably most concerning is a suspected 'bad batch' of fuel. In one of my last loads of waste oil, there was some fire-resistant hydraulic oil that got mixed in. It burns fine once it's up to temp, but I can't forgeweld with it, and I've had no luck working wrought with it. I'm wondering if it has stuff in it that's possibly contaminating my steel? If that's the case, could it be causing other problems in my finished blades that won't show up until the end user has the blade?

I don't expect many guys here are familiar with waste oil since it seems to be an unusual choice for a forge, but if any of you have ideas, I'd love to hear them. $170 for 10-20 hours of forge time is pretty steep.
 
I'll bet waste oil would be hard to handle inside. It might not need a gal/hr, I've not measured it myself, just seems that might be about what I get.
 
Some data points:

I run a single burner venturi forge. A 20 pound tank might run at welding temp for 5 hours. My configuration is not very efficient.
During use, the tank gets cold from the evaporation of gas and can't maintain pressure. You can put it in a warm water bath to mitigate this. If you don't, it could lose welding temp after about 3 hours.
I recently upgraded to 100 pound tanks. Three 5 hour sessions and we're still going, but I don't have a number for total runtime.
 
A 20 lb propane tank should have about 4.7 gal, and you got perhaps 3 gal before freezing up? Is that 5 hrs runtime using the warm water bath? Perhaps got 4 gal used for 5 hrs runtime? .8 gal/hr?

I recently upgraded to 100 lb tanks myself - last Thanksgiving when TSC had them on sale for $100 each. Got two of them. I ran out in my first tank yesterday, changed them then noticed the bottom was frosted over. Weighted the tank and still had 10 lb (≈2.5 gal?) left.

I'm thinking perhaps 1/2 gal to 1 gal/hr would be a decent number for propane usage?
 
I asked some of the guys in a statewide blacksmithing group, and they're telling me about what you guys are saying. 1/2- 1 gph for general forging, just over 1gph for welding. Most of those guys are on the road system, and can get propane for about $3.00 a gallon. I'm seriously thinking about getting/building a propane forge for more sensitive jobs like welding, or quick (under 30 min) jobs. It's expensive, but not as bad as I had thought it would be.
 
I most often see waste oil forges as dual fuel.

A propane burner to warm it up until the oil runs well.
 
I was just getting ready to post the same comment as the Count. Build a dual burner forge with one propane and one waste oil. After it heats up, start the oil and when it is running OK shut down the propane. For short time tasks, just use the propane.
 
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