Acetylene b tank what size welding tip is max?

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rodm1

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I have an acetylene b tank and would like to practice welding with it. What is the rule on max tip size for welding and cutting? What would be the max plate thickness you can weld? I know you can stretch these numbers but just won't a general guide new to acetylene I use LP currently.

Anyone make a hand turn nob wrench for b tank? What about a valve protector?
 
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as far as I know there is no rule on max tip size for tanks, but the larger the tip and the time will determine how often you will need to refill any size tank.
Dave
 
Pressure is the limitation, which you will lose faster with a small tank. The oxygen pressure/volume for cutting is bigger issue.
 
There's a limit for withdrawal rate for an acetylene tank, I think it's 1/7th the tank size per hour. Look that up, because I could be wrong on that. Faster rates can cause issues. Typically this becomes an issue if one puts on a big rosebud tip on a small tank. High rates of withdrawal can cause the acetone in the tank to exit the tank and mess up your regulator, it may also make the acetylene unstable, both of which are not desirable. For high consumption it's typical to manifold multiple tanks to reduce an individual tank's rate. For folks with a single small tank, we have to use smaller tips. I will look to see if I can find any more info on this.

If you are not using acetylene, then there may be different rules.
 
There is a maximum flow rate for acetylene tanks. The rule of thumb is that the rate should not exceed 1/7th the capacity of the tank (SCFH). The reason is that acetylene is dissolved in an acetone/diatomaceous earth matrix to make it safe to store under pressure. Faster discharge rates will carry acetone with the acetylene which will deplete the amount of acetone in the tank,creating a potential explosive condition.
 
Concerning oxygen delivery, any limitation is more likely be due to the size of the regulator rather than tank size. The tank is capable of discharging at a higher rate than would be experienced in typical cutting operations.
 
With liquified gases like propane, the limitation will be due to the cooling effect due to evaporation of the fuel. Rapid discharge will chill the contents of the cylinder, slowing the rate of evaporation. This can be overcome with smaller tanks by placing the tank in a warm water bath to prevent excessive chilling. If dealing with a liquid withdrawal, the cooling will occur at the regulator with the same effect.
 
1/7th rule Here's a link. Also has info at bottom of page from Harris. 1/7th rule has been changed to 1/10th, to reduce likelihood of drawing off acetone from the tank. So your tip size should have a SCFH rating, if you are under 1/10th the capacity of your tank, you should be ok. Bottom line, don't expect to weld 2" plate off your B tank. Other than that, look up the flow rate of your tip.
 
Thanks that helps! I looked at the portable kits with MC tanks they spec them out at 1/4 welding and 1/2 cutting the B tank looks like it maybe useful after all.
 
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