First knife, first problem

G

GemaRastem

Joined
Jun 26, 2017
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I just finished my first knife out of a railroad spike. It turned out pretty good but I had problems with my homemade blown propane forge. After about 15 minutes of forging, the propane tank would shut off. I had to close the main valve on the tank, take off the regulator, and relight the forge. This has happened with 2 different propane tankss. I have the regulator set for about 5 psi, and then use a ball valve after to regulate till I get the flame I want. Any ideas?
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Sounds like the tank is freezing up. Though I wouldn't think that would happen in just 15 minutes at 5 psi.
 
BBQ propane tanks have a safety feature that is explained thoroughly here:
https://tvwbb.com/showthread.php?49713-Weber-Q-low-flame-or-no-flame


... A secondary function of the OPD is to shut down or reduce the flow of gas in the event of a significant depressurization of the propane hose, such as would happen if the propane hose were severed.


Why is this happening if the hose isn't severed?

In most cases the OPD is triggered because of the initial flow of gas into the adapter hose which triggers the OPD, combined with insufficient wait time to allow the pressures in the tank and the hose to equalize. If the barbecue is lit too soon after turning on the tank, the hose never pressurises and so the OPD ball never drops to allow full flow of gas. In most cases the equalization of pressures takes less than a second, however when using an adapter hose this can take much longer because the high pressure gas (150+ PSI!) rushing down several feet of hose triggers the OPD long before the hose has a chance to fully pressurize.


But my barbecue works for a while then stops, what gives??

When using an unregulated adapter hose, even if the OPD triggers prematurely there is still sufficient pressue in the hose to run a low demand appliance for several seconds to several minutes. A standard Propane (LP) appliance runs at 11" WC (Watercolumn). 1 PSI is equal to 27.68" WC, so a propane appliance runs at less than half of a PSI, thus if the hose contains even 50 psi it can still contains enough gas to run a low BTU appliance for a while.
 
I'd be interested to see your propane forge setup, or other's if they have a reliable system they care to show. I built one out of a large soup can using sand + Plaster of Paris, and just using hand-held propane/and mapp gas torch stuck through an inlet in the side. It works OK, but isn't ideal by any means. I think I'm going to need something better sooner rather than later though.
 
P.Brewster said:
BBQ propane tanks have a safety feature that is explained thoroughly here:
https://tvwbb.com/showthread.php?49713-Weber-Q-low-flame-or-no-flame


... A secondary function of the OPD is to shut down or reduce the flow of gas in the event of a significant depressurization of the propane hose, such as would happen if the propane hose were severed.


Why is this happening if the hose isn't severed?

In most cases the OPD is triggered because of the initial flow of gas into the adapter hose which triggers the OPD, combined with insufficient wait time to allow the pressures in the tank and the hose to equalize. If the barbecue is lit too soon after turning on the tank, the hose never pressurises and so the OPD ball never drops to allow full flow of gas. In most cases the equalization of pressures takes less than a second, however when using an adapter hose this can take much longer because the high pressure gas (150+ PSI!) rushing down several feet of hose triggers the OPD long before the hose has a chance to fully pressurize.


But my barbecue works for a while then stops, what gives??

When using an unregulated adapter hose, even if the OPD triggers prematurely there is still sufficient pressue in the hose to run a low demand appliance for several seconds to several minutes. A standard Propane (LP) appliance runs at 11" WC (Watercolumn). 1 PSI is equal to 27.68" WC, so a propane appliance runs at less than half of a PSI, thus if the hose contains even 50 psi it can still contains enough gas to run a low BTU appliance for a while.
Click to expand...


So is the remedy to wait for ten minutes or so after turning on the tank side before turning on the torch side ?
 
just an idea- open the ball valve all the way and use the regulator to govern the gas. having the regulator open with very little gas going thru it may be compounding the issue because there is pressure on both sides of the regulator getting trapped by the ball valve.
 
If you aren't using the regulator to adjust the flame, I would recommend it. I have had zero issues with mine shutting down due to the safety valve built into the tank, or freezing up. I usually have to open and close the valve about 4 or 5 times initially to get the safety to quit "clicking" till i'm fully pressurized to my ball shut off valve. Once i get it to quit "clicking" the safety valve I open the ball valve a smidge till I hear gas flowing and light my forge, once lit I open the ball valve all the way and it runs smooth. All of this is usually done around 5-10 psi, then I tune down to get to 1 psi for doing my HT. I've also run mine at 15-20psi for an entire 20lb tank forging some steel and have never froze up, it's gotten cold to touch the tank, but has not froze. I'm also in SC and haven't tried it in Jan/Feb when we have out winter.
 
Kevin McGovern said:
So is the remedy to wait for ten minutes or so after turning on the tank side before turning on the torch side ?
Click to expand...

Yeah, I think that's the concept but 10 minutes sounds excessive. I am led to believe that opening the tank valve very slowly also helps.
 
Fear not however, your next knives will have problems as well. I have yet to make a knife that didn't present at least one.
 
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