Propane or Coal. Whats The better bargin today?

[HWHII]

Yesterday I filled up my propane bottles. 62 gal. at $2.59 per gal. Coal around here runs about $30 for a 50lb bag. I don't forge every day and sometimes not for a few days with propane. When I do I am running 8 psi. At this rate has anyone figured out how many gal. per hour you may be burning. On Fridays I use 2 coal forges for my class for 5 students and we use about 10lbs in 1 hour. This I can see and calculate which is .60 per lb. or $6 hr. or $3 per forge. If I am burning a gal. per hr. of propane it is pretty much a wash. I hope someone can help me out here.

[MattBower]

PSI alone tells you nothing except . . . PSI. If you throw in an orifice size, someone here may be able to estimate how much propane you're using in an hour. A probably more accurate way would be to weigh the tank, run the forge for a while (preferably several hours -- and you want to time it reasonably precisely), then weigh the tank again. Difference in weight divided by number of hours gives you pounds per hour. And propane is usually sold by the pound, not the gallon, because its density varies considerably depending on ambient temperature.

[2Tim215]

Some calcs I did for my oil forge with comparison to gas - not 100% but close

Some calculations:

Gas = R390-00/20kg = R19-50/kg - a gas bottle running at optimum gives me 12 - 16 hrs of forging and at 16 hrs works out at 1.25 kg/hr @ R24-37/hr

WVO (waste veg oil) = R2.50/ltr. I dilute with diesel so it works out at around R50.00/ 20ltr + R100-00 for 10ltrs diesel = R150.00 for 30ltrs. I use 1.5 ltrs/hr and that gives me 20 hrs forging @ R7.50/hr

So:

Gas = R24.37/hr
WVO = R7-50/hr

Even if I double my oil usage it still works out cheaper than gas by half.


Propane gives about 25756 BTU's/ltr and @ 1.25ltrs/hr it works out to 30945 BTU's - for welding I would think you would need a bit more depending on the size of the forge. Ron Reil says you want about 450 BTUs/hr per cubic inch of forge volume to hit welding heat in a presumably well-insulated forge. This forge is 540 cubic inches so I would need 243000 BTU's/hr. Diesel has around 37333 BTU's/ltr (WVO a bit less) - so for this size forge I would need to put through 6ltrs/hr to hit welding temp if my calculations are right and that is the critical thing - you need to put the amt of fuel required to reach the heat required and how you atomize the oil can affect this.
Also, the dimensions, shape and insulation of the forge can affect how hot it gets - this forge is difficult because of it's size and shape but I am happy with forging heat because that is what it was designed for.
The cost calculations I did above are for a normal sized pipe forge that most knife makers use - for this forge I would need 8kg/hr of gas or 6lt/hr of WVO to hit welding temp - excessive at R150-00/hr for gas and R30-00/hr for oil - but oil is still a lot cheaper.

When you start doing calcs like this it makes you realize how much forging a knife or Damascus costs and how important the right forge is in keeping costs down by retaining heat well, getting hot fast and still being strong enough to last.

So to make it simple - you would need a 100 cubic inch forge running at 1.3 ltrs/hr to reach welding temp - that is the forge would need 45000 BTU's/hr with WVOl giving you around 35000 BTU's/hr - divide 45000 from 35000 = 1.3 ltrs/hr.
1 cubic inch is 16.3 cubic centimeters

To calculate the cubic volume of a rectangle is length X width X height
Volume of a cylinder is H(PI)R2 - height x pi X radius squared

My knife forge 6cm® X 30cm(L/H) = 6 X 6 x 3.14(pi) X 30 = 3391 cm3 divided by 16.3 = 208 cubic inches so I would need around 2ltr/hr at R5.00/hr running cost. But take into consideration that my forge is heavy cast able and retains heat well and that the btu's required are for REACHING welding heat - not maintaining it - experience has shown me that once at welding heat you can lessen the fuel used to maintain that heat so the cost and fuel usage would lessen once you reach the required temp.

[Rich Hale]

When I use my gasser for more than a short heat, I turn the gas off each time I pull steel out the back on when I need another heat, the heat in the forge ignites the gas. I can use a bbq size tank for wot I feel is a long time. The same with a hand cranked blower on a solid fuel forge. stop the air while you are striking and use less coal. On my solid fuel forge I have thought about putting in a on off foot switch to the electric blower. It woiuld not change the speed setting on the fan. just shutit off when I do nto have steel in. As for your calcs. Youi are the only one that can do that. Keep recdords and look at them for answers. I strongly suspecf you will find that it really will not make a lot of difference in anything except if you are doing price estimates for work orders. And even then it will be just a guess unless you are doing one more of a long run of similiar pieces.

[Borntoolate]

Without doing any calcs or considering all the other details above my belief is that coal is way cheaper. I must admit that I made my own gasser from 14" pipe that is 24" long. I have about 4" of kaowool everywhere on the inside including the back. I have a firebrick covered opening that is about 5"x6". I have two burners that I made myself. So more than likely my gas forge is not very efficient. Achieving a welding heat is nearly impossible. It runs rich unless I use my air injection superchargers *small tubes that blow comressed air into the burner opening controlled with needle valves".

I do use it for bigger pieces that I want to heat entirely.

[SmoothBore]

The cost of coal also varies greatly, depending on your location.

Here, in Southeastern Pennsylvania, I'm paying $17 for a hundred pound bag of Bituminous Coal, ... and Anthracite is considerably less than that, ... because it's mined nearby.

The kind of fire you need, depends so much on the type of work you do, ... that it's nearly impossible to make an honest comparison.

I like a coal fire for playing around with a wide variety of work, ... but if I was trying to do any kind of production work, the convenience of a Gas Forge would be very tempting.


.

[KYBOY]

Not even close around here..I live in coal country..$40 gets me a 40lb tank of propane..The same $40 gets me almost half a ton of good quaility coal..That half ton of coal will go many,many....many times farther than that 40lb tank of propane..

[S.Willis]

Not even close around here..I live in coal country..$40 gets me a 40lb tank of propane..The same $40 gets me almost half a ton of good quaility coal..That half ton of coal will go many,many....many times farther than that 40lb tank of propane..

About the same price here. The 1/2 ton of coal will last for months . The same dollar amount of propane will only last for hours.

[musk-rat]

I am in the same boat as KYBOY and S.Willis. Coal is so cheap in my area that I tend to use it 99% of the time. If I am only going to play around for an hour or two with small stock I might use my one burner gaser. I think it really depends on your location and your personal preference to which is the better bargin.

[Old N Rusty]

We pay a lot for good coal down here on the Bayou, AND have to drive 80 miles round trip to buy 100lb bags for $40. Ea. Propane i get delivered from the welding supplies, I own a 100 lb tank and get it filled and returned for $1.00 lb. For the other solid fuel forge it is lump charcoal from Winn Dixie 25lb bag for $8.00 My building has hi pressure natural gas piped in 1-1/4 " that I am reducing to 3/8" for a blown gasser. it doubles as a space heater and a month of cold weather and forging scrolls has cost as much as $45. gas charge on the utilities bill. All the things Mr. Hale recommends are good, I have a switch and an intake restrictor plate on the coal forge blower. The charcoal forge has a hand crank buffalo blower. I still want to make an induction forge from an old Craftsman bug zapper when I have the entire roof, 10,000 square feet covered in solar panels. That would be cooking without gas!

[ramsies11]

here in S missouri my closest coal supplier is about 130-140 miles away (one way trip) and hes an amish man who imports it from philly, but the gas here, if i get a big welders propane bottle (the ones taller than me) they run about the cost of 2 bags 25lb of lump charcoal. (bout 50bucks before tank rental price is added in) im currently in the process with my father of making a gasser forge. i can do some quick calcs then, but i still dont know really.

[HWHII]

I have often be confused by the way they sell propane. Bottles are measured by how many pounds they hold. All the years I have bought propane its advertised price is per gallon and is measure by a pump per gallon. I have never seen it sold or measure buy price per pound, but yet some of you buy it this way. Can you tell me how they do it?

[ThomasPowers]

Here they sell propane by the gallon as that's what the pump measures and it's corrected for temperature---just like a gasoline pump.

Coal is a 150 mile each way trip that drives the price up, propane I can buy 3 different places at 9pm on a Sunday evening!

Note that the gauges for most propane systems are almost always off and 50% off is not unknown---when is the last time you calibrated your gauge?

Also how well insulated is your forge? I noticed that the last time I relined my forge with a thicker liner of kaowool I was *melting* steel in it at the same "psi" as previously I was just heating it at.

If I still lived in OH I would probably use mostly coal, here in NM I use mainly propane.

[Ten Hammers]

Nurse tanks ( large tanks to supply homes and industry ) are measured in gallons held. They have specs stamped on a dataplate that is attached to the top of the tank normally. They are filled
( common case ) by the tank truck. They have gauges to measure % in tank. Truck driver fills to whatever % you have asked for or full ( as close as he wants normally). This is measured in gallons pumped on the meter on the filler on the truck and you are charged the gallon price of the day OR your contract gallon price. There are above ground and underground tanks. Most will draw gas from the internal dip tube. Large tanks are rated in gallons normally. They will have a regulator to take tank pressure down. A second stage regulator on the house (example) takes the first stage down to 11 WCI to enter the appliance control.

Bottles are weighed fill here locally and in many places. They have data stamped in the handle normally. Water capacity tells how much liquid the tank is rated for (as do the large nurse tanks). There is a chart by the filler station (normally) that the filler uses to set the scales. So much WC = so many gallons in the tank. The scales are set and when they balance, the filler is shut off.

Some places will measure the existing weight ( tank not empty ) and charge you the difference when they have the full weight. Some will charge you a full weight fill each time. Normally there will be a set price for bottle size fill. Common upright bottles draw gas. Horizontal ( lift truck for example) draw liquid. Different needs. Different valves. You have one regulator on your home gas grill or other appliance (gas draw). Weed burners will normally run on tank pressure. Motorized devices (lift trucks, tractors, cars, large trucks) may have liquid tanks or gas draw ( normally liquid in my experience). they are regulated at the point where the fuel air mixture enters the motor. Hope this helps. I'm sure there are folks with better information in some of these areas I have described.

[MattBower]

Interesting discussion here. I'm learning a lot. I did not realize that propane is temperature-compensated when it's sold by volume in this country. I'm glad to know that.

However, outside Hawaii, retail gasoline and diesel are not temperature compensated in this country. (I didn't know that, either, until I looked it up just now.)

[Guest baddog]

Granted I don't have a lot of experience, (less than a year) but we have just switched back to coal after about 8mos of propane forge. Propane went up from $15 a refill on a 20# tank to $19 about 2 weeks ago. I forget what we paid for the coal but it was 130 mile drive to get it. Coal for normal forging, propane for mass production is what we are looking at.

[Francis Trez Cole]

it depends how much blacksmithing you do. A 100 lb of coal will last me about 3 days at $35.00 with my gas forge it will run 18 hours on 100 pound tank of propane. The last time I filled up my tank it was over $100.00. so for me coal is cheeper

[HWHII]

Nurse tanks ( large tanks to supply homes and industry ) are measured in gallons held. They have specs stamped on a dataplate that is attached to the top of the tank normally. They are filled ( common case ) by the tank truck. They have gauges to measure % in tank. Truck driver fills to whatever % you have asked for or full ( as close as he wants normally). This is measured in gallons pumped on the meter on the filler on the truck and you are charged the gallon price of the day OR your contract gallon price. There are above ground and underground tanks. Most will draw gas from the internal dip tube. Large tanks are rated in gallons normally. They will have a regulator to take tank pressure down. A second stage regulator on the house (example) takes the first stage down to 11 WCI to enter the appliance control. Bottles are weighed fill here locally and in many places. They have data stamped in the handle normally. Water capacity tells how much liquid the tank is rated for (as do the large nurse tanks). There is a chart by the filler station (normally) that the filler uses to set the scales. So much WC = so many gallons in the tank. The scales are set and when they balance, the filler is shut off. Some places will measure the existing weight ( tank not empty ) and charge you the difference when they have the full weight. Some will charge you a full weight fill each time. Normally there will be a set price for bottle size fill. Common upright bottles draw gas. Horizontal ( lift truck for example) draw liquid. Different needs. Different valves. You have one regulator on your home gas grill or other appliance (gas draw). Weed burners will normally run on tank pressure. Motorized devices (lift trucks, tractors, cars, large trucks) may have liquid tanks or gas draw ( normally liquid in my experience). they are regulated at the point where the fuel air mixture enters the motor. Hope this helps. I'm sure there are folks with better information in some of these areas I have described.

Thanks Ten Hammers! This anwsered my question!