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Forge working great for 45 minutes then :-(


Bking1340

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Good day all

Can someone please watch my video and listen to the sound my forge are making. It works great for +- 45 minutes - heats up fast and a nice growl/dragon sound. Then after +- 45 minutes a dull sound and you can hear and see it`s not heating great anymore.

https://youtu.be/ZDySpG2h0sE

I went for a blade smith course on December at Neels van den Berg (great bloke - also on youtube) and also bought this forge from him. Nobody got problems with theirs except me and he sold hundreds of these. I phoned him and he immediately send me a complete new burner with regulator - same problem.

I must add that it is winter here and in summer time it also had this problem but only after about 2 hours.

I played around with the nozzle - on the edge of the air opening - 5mm(0.2 inch inwards/outwards)

Burner tip flush inside - moved out in increments of 10mm(0.4 inches) to 30mm(1.2inches)

Different air openings, different size gas bottles - 14kg/19kg.

Any help will be appreciated.

Jaco

 

 

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Welcome aboard Jaco, glad to have you. If you'll put your general location in the header you might be surprised how many of the Iforge gang live within visiting distance. It's hard for me to tell what your forge is doing. It's a common problem when folk video something, every time you changed the angle of your (call it camera) it changed the direction the mic was pointing and what we hear. 

The guys are probably right, your tank is probably freezing up. The easy solution is to buy a larger propane tank, floating a 20 lb. tank in a tub of water works but it's a work around not a solution. 

Frosty The Lucky.

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What were you doing with the choke in the video? A wide angle tripod-mounted view would probably be more useful for diagnosis than the fast-moving tight stuff, which is pretty disorientating.

Am I reading things correctly? I think what I am seeing is as follows:

Forge runs well, then it looks like it goes horribly rich and presumably the temperature drops if you let it? You close the choke and open it and it starts burning correctly for a short while before going horribly rich and repeating?

If I've read it wrong, please ignore the following.

If it seems something like it, what gas pressure are you running at? Can you try turning it up significantly?

What I think is happening is as follows: From startup, everything is hunky-dory. The gas pressure is high enough that the mixture is moving towards the forge faster than the flamefront can burn through the mixture in the opposite direction and the flame stays in the forge. After about 45 minutes "something" changes and the forward mixture speed becomes less than the backward flamefront speed. The flame burns back into the burner tube. Because the mixture is now burning in the tube, it expands as it burns and increases the back-pressure, reducing the amount of air drawn in, sending the mixture excessively rich and reducing the forge temperature. You close the choke briefly, cutting off the air supply and causing the flame in the tube to go out. You open the choke, re-establishing mixture flow, which ignites as it reaches the hot forge and all is wonderful until the flame speed exceeds the mixture speed again.

One possibility is that the mixture speed is dropping because the cylinder temperature is dropping enough to reduce the delivery pressure. If you have a pressure gauge, you can check whether the pressure remains constant from startup to the problem occurring and maybe get enough information to help with the diagnosis.

Another possibility is that the forge temperature has risen to the point where the flame speed is faster than the mixture speed provided by the regulator. Flame speed in a Propane/Air mixture is dependent on temperature, pressure and the air:fuel ratio. If you have any headroom on your regulator setting, turning it up should raise the temperature at which it becomes a problem, hopefully out of the working range.

 

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Listen Im amazed about all the replies, really appreciated. I will change my avatar shortly.

Timgun u r correct

"Forge runs well, then it looks like it goes horribly rich and presumably the temperature drops if you let it? You close the choke and open it and it starts burning correctly for short while before going horribly rich and repeating?" 

Sorry for that crappy cellphone video, but I just checked it again and the mic do not change while moving my phone, it's the sound of the forge/burner changing and im only making changes on the air as on the video to show that if I close and open the air again, it's growling nicely for a few seconds and then back to that dull sound with big blue flames coming out of the forge.

The ambient temperature in my garage are 10°C (50F) winter times and 25°C(77F) summer times without the forge running. Like I said summer times the forge are only acting up after 2 hours.

I tried 3 different bottles, 2x 19kg(41,8 pounds) and 1 x 14kg(30.8 pounds). I can't see that the tanks are freezing up (nothing at the valve or regulator seems odd). 1 are half empty , 1x full and 1x 1 hour runtime.

I start the forge on 50kpa(7.25 psi), but tried different setting up to 130kpa(18.85 psi) which according to the manual are the maximum. Tried 3 different regulators which 2 of them were brand new.

When the forge goes to that dull sound, the regulator pressure gauge are exactly where I set it and do not drop or increase.

The last thing I must add is that my forge are in a double garage - 2 big front doors and one normal small back door. Summer times my one big front door were a 1/4 open, and the small back door due to the garage getting too hot. Now in winter I only open the small back door. 

So the next thing I will try next week (very busy at work) is to open both front doors and the small back door + a fan, maybe the oxygen are dropping and the co are increasing.

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back when overflow valves were federally mandated on propane cylinders, some states got the bright idea to include internal control valves on five gallon "barbecue tanks"; they do no harm on such tanks, so long as you are only running a barbeque from them. However, internal control valves do loads of mischief if you try to run a forge from a  fuel cylinder that has one of them. If you live in one of these states, purchase a seven or ten gallon propane cylinder to make an end-run around the problem. 

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It doesn't sound like a cylinder problem, as there is no pressure reduction. 

I could be completely wrong, but I don't think the atmosphere in the garage will be the cause of the problem either. I would very strongly advise installing a Carbon Monoxide alarm or two if ventilation is restricted: death tends not to improve your bladesmithing. CO monitors are cheap, effective and will alert you to a potential problem while you are still upright. 

If the CO2 level in the atmosphere is rising, and the O2 level is dropping, by enough to significantly affect flamefront speed, I would expect the change caused to be a reduction in flamefront speed, which I would expect to reduce the problem, not increase or initiate it.

If playtime is tight, I'd get a higher-pressure regulator before trying again. Most people seem to use at least a 0-30 PSI (about 200 kPa) regulator. I prefer 0-60 PSI/0-4 Bar (about 400 kPa) regulators. Is 130 kPa the maximum for the regulator, or "just" the maximum recommended pressure for the burner? If the latter, it would be worth speaking to the burner manufacturer for their thoughts on turning up the pressure.

Going from 50 kPa to 130 kPa will increase the gas flow (and with it, the air flow) by the square root of the pressure change. The square root of (130 kPa/50 kPa) is about 1.61. That is not a huge working window.

In many cases, a burner needs to be started at a lower pressure to avoid flame lift-off in the cold forge and it can be turned up once the forge temperature has reached about 800 degC (1472 degF) to get up to working temperature. I don't know whether this applies in your case, but if you need more than 50 kPa to reach working temperature, you will have even less headroom to turn it up if/when you run into burnback issues.

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I have a gas detector in my garage which measures O2 %, CO ppm and Explosive LEL. Used it on my previous forging session (Only half an hour) and could not see any changes.

The pressure gauge reads from 0 - 250kpa. Just went through the manual again and the maximum recomended pressure are 150kpa. On the regulaor it`s written, 0-30psi.

I normally heat up the forge at 75kpa and after 5-10 minutes the refractory starts to glow yellow. After 15 minutes I go down to 50kpa and 6mm 5160 flatbar will reach forging temperature in a breeze.

Jeez this is a bummer - Kevin Harvey - ABS master bladesmith are living 50 miles from me using the exact same forge with exact same nozzle burner settings without any issues.

Neels van den Berg where I bought this forge are living 90 miles from me using 2 of these for his bladesmith classes 5 days a week and they run for minimum 4-5 hours a day. 1 of them are 9 years old and only now needs some tlc, but still working good.

I can`t see that it can be the forge itself - dont see any cracks or anything odd inside or outside.

I uploaded another video just to show the forge/gas cylinders and my garage layout.

 

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