Propane Forge Troubles

J

Jak Epp

Joined
Dec 27, 2023
Messages
139
I have a 40 lb tank for my forge, and I filled it about a month ago when it was very cold (as in below zero outside). When I hooked it up the my forge, it worked for a few minutes and then the forge started belching out big yellow flames from both ends without the light blue flame I normally see. The propane line and regulator were frosted, and the flames took a while to die down after I closed the tank and regulator. I assumed that because I had filled it when it was cold (when the propane had lower pressure) and then used in a warm garage, the pressure had rose significantly and caused problems. So, I switched to a smaller 20lb tank and have used that since. In the meantime, I have used the 40 lb tank with the grill, and haven’t experienced any issues.

Today I figured that enough propane had been used for the pressure to go down enough to work with the forge again. Well, it worked fine for about 5-10 minutes before it did the same thing as before: 2 foot yellow flames from either end of the forge, a lack of the normal quiet roaring, and no light blue flame. The propane hose and regulator had iced over again, just like before. A 20lb tank still works fine with it, so I don’t think its a problem with the regulator. Is the tank still too full?
 
Jak Epp said:
I have a 40 lb tank for my forge, and I filled it about a month ago when it was very cold (as in below zero outside). When I hooked it up the my forge, it worked for a few minutes and then the forge started belching out big yellow flames from both ends without the light blue flame I normally see. The propane line and regulator were frosted, and the flames took a while to die down after I closed the tank and regulator. I assumed that because I had filled it when it was cold (when the propane had lower pressure) and then used in a warm garage, the pressure had rose significantly and caused problems. So, I switched to a smaller 20lb tank and have used that since. In the meantime, I have used the 40 lb tank with the grill, and haven’t experienced any issues.

Today I figured that enough propane had been used for the pressure to go down enough to work with the forge again. Well, it worked fine for about 5-10 minutes before it did the same thing as before: 2 foot yellow flames from either end of the forge, a lack of the normal quiet roaring, and no light blue flame. The propane hose and regulator had iced over again, just like before. A 20lb tank still works fine with it, so I don’t think its a problem with the regulator. Is the tank still too full?
Click to expand...
Have you used that same 40# tank before with good results?

Is it a forced air burner or a venturi burner forge?

Hoss
 
As a beer brewer with propane powered equipment I have some ideas that might help. First of all - pressure inside propane tank is constant regardless of propane level, as long as there are liquid, there are constant pressure above that liquid. Always the same, unless the last liquid evaporates and you have empty tank. What can make a difference is gas mix inside that tank. I live in eastern Europe so I will speak how things are done here, but I think physics are universal around all globe. When I buy propane tank, I get propane/butane mix, usually 50-50 to 70-30% ratio. Butane is a little cheaper for company who sells gas, so they tend to max out butane proportion. Culprit there is that butane has higher evaporation temperature and in winter, you may need to use clean 100% propane gas to not get ice frost on your regulator and lines. Basically speaking, you have micro refrigerator on your pressure regulator - when liquid is forced to evaporate, it takes energy (heat) from surrounding environment and cools. That's how sweat cools us and how refrigerators work.
Long story short - you have different than usual gas mix in your 40lb tank. You can use it if you place it in big bucket with warm water. Basically you need to reasonably warm that tank to help liquid-gas phase change, which occurs in gas regulator. In brewing world we have all kind of fancy electric blanket heaters to wrap propane tanks, you get the idea. Just don't heat with open flame. Don't do that.
 
I suspect either overfilling and the tank is spitting liquid propane down the lines, or a bad regulator that is trying to dump too much propane occasionally. The frosted lines indicate liquid propane evaporating in the regulator and lines. It may be that the evaporation is freezing up the regulator and not allowing it to "regulate" the flow. Try a neighbor's half empty propane tank and see if the problem disappears.
 
DevinT said:
Have you used that same 40# tank before with good results?

Is it a forced air burner or a venturi burner forge?

Hoss
Click to expand...
I have had the 40# tank for almost a year and had never had any problems with it. It's a venturi burner.
Stacy E. Apelt - Bladesmith said:
I suspect either overfilling and the tank is spitting liquid propane down the lines, or a bad regulator that is trying to dump too much propane occasionally. The frosted lines indicate liquid propane evaporating in the regulator and lines. It may be that the evaporation is freezing up the regulator and not allowing it to "regulate" the flow. Try a neighbor's half empty propane tank and see if the problem disappears.
Click to expand...
I have used a smaller 20lb tank in the meanwhile without any issues whatsoever, so that leads me to think its a problem with the 40lb tank, not the regulator. I had neglected to mention it in first post, but while the burners are acting up, you can see through the air holes a fine mist coming from the nozzle.
 
The fine mist is liquid propane coming up the hose. It gets past the regulator. Unless the tank is sideways or upside down, no liquid should be going past the valve. If it is greatly overfilled, that could be the issue. If the regulator is far too open it can allow boiling propane up the hose. If you are looking at the pressure gauge on the regulator, it may be bad. They are usually cheap gauges and often go bad. Replace it if you have any doubt.

First test- Try taking the tank out back and opening the valve for several 10 second bursts. Let the tank warm back up and try the burner again. If it is OK now, weigh the cylinder and note the weight. This is the FULL weight. It was overfilled. If the problem is still happening, try the next tests.

Second test - Turn the tank valve off, the regulator all the way closed and open the needle valve on the burner all the way open. You should hear no hiss and there should be no gas to ignite if you put a torch in the forge. Open the tank valve. You should still hear no hiss and no gas should be flowing. Slowly open the regulator until you here the barest hiss and light the forge. It may be too low pressure to sustain the flame and you may have to open the regulator more. Once the forge is running on the LOWEST flame that is stable, let it run for ten or fifteen minutes. If all is good, the regulator was likely too open before. If there was too much gas flowing before you could get the forge running on low, the regulator is bad. Now, open the regulator to a full burn. A proper full flame should have just a tad of dragon's breath. Once running right at this flame, you have found the HIGH setting on the regulator.
 
Stacy E. Apelt - Bladesmith said:
The fine mist is liquid propane coming up the hose. It gets past the regulator. Unless the tank is sideways or upside down, no liquid should be going past the valve. If it is greatly overfilled, that could be the issue. If the regulator is far too open it can allow boiling propane up the hose. If you are looking at the pressure gauge on the regulator, it may be bad. They are usually cheap gauges and often go bad. Replace it if you have any doubt.

First test- Try taking the tank out back and opening the valve for several 10 second bursts. Let the tank warm back up and try the burner again. If it is OK now, weigh the cylinder and note the weight. This is the FULL weight. It was overfilled. If the problem is still happening, try the next tests.

Second test - Turn the tank valve off, the regulator all the way closed and open the needle valve on the burner all the way open. You should hear no hiss and there should be no gas to ignite if you put a torch in the forge. Open the tank valve. You should still hear no hiss and no gas should be flowing. Slowly open the regulator until you here the barest hiss and light the forge. It may be too low pressure to sustain the flame and you may have to open the regulator more. Once the forge is running on the LOWEST flame that is stable, let it run for ten or fifteen minutes. If all is good, the regulator was likely too open before. If there was too much gas flowing before you could get the forge running on low, the regulator is bad. Now, open the regulator to a full burn. A proper full flame should have just a tad of dragon's breath. Once running right at this flame, you have found the HIGH setting on the regulator.
Click to expand...
Thanks! The regulator works fine with a 20lb tank, so I’ll assume its over filled.
 
Did you buy the 40# tank new?
The reason I ask I recently converted my two gasoline generators to use LP. It worked great and now I don't have to worry about storing gasoline and it going bad.
Anyhow they stress the following in their instructions
"
Make sure that you are using propane tanks that have definitely been filled at least 4 times. New tanks will have air in them that will cause this issue.
 
LCoop said:
Did you buy the 40# tank new?
The reason I ask I recently converted my two gasoline generators to use LP. It worked great and now I don't have to worry about storing gasoline and it going bad.
Anyhow they stress the following in their instructions
"
Make sure that you are using propane tanks that have definitely been filled at least 4 times. New tanks will have air in them that will cause this issue.
Click to expand...
Yes, I bought it new. I’m not sure how many times I’ve filled/emptied it, at least 3 times, maybe as many as 5.
 
If they're filling it to 40# there's not much space for air even if it's the first fill. I'm agreeing the overfilling.
 
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