How to calculate this? Are there any general formulae? Besides, since a
given tip has a given set of OA pressures, which is the
acceptable variation range? And, there is some rule of thumb regarding how
long should be the flame inner cone as per tip size?
Thanks in advance
Cutting tip manufactures have charts for the asking or download that
show flow rate and pressure setings.
Acetylene cylinder pressure is poor indicator of gas in cylinder.
Acetylene cylinders and propane cylinders are stamped with empty
weight called tare weight. 14.6 square feet of Acetylene per each
pound in cylinder above tare weight. If you weigh cylinder you can
calculate how much gas has been used and how much is left. That with
time torch was burning lets you calculate flow rate.
Must keep Acetylene cylinder pressure above 25psi or acetone will be
drawn out with gas.
I did not pay close attention to the tip chart and the flow rates were at
far right edge of the page. Dumb of me!
Now, if 14.6 ft³ each @, so my 3 kg tank has 87 ft³ aprrox.
therefore 1/7 of that is 12.5 ft³. .
This would mean the largest tip I can use safely is a #4. please correct
me if I'm wrong
thanks for the 14.6 data.
That's right, for your tank size a Victor #4 welding tip would be max.
For a Harris tip it would be a #6, and for an Airco torch it would be a
#5 (same flow, different tip numbering systems for different torch
manufacturers). This tip size is rated for single pass welding 1/4
Note too that cutting tips have yet another numbering system. For
your tank size you're limited to a #1 Victor cutting tip. That would
also be a #1 Harris, or a #2 Airco cutting tip. This tip size is rated
for cutting 3/4 inch steel.
For heating, you're limited to the smallest rosebud tip, a #5.
For larger jobs, you either have to go to a larger acetylene tank,
or gang multiple acetylene tanks together with a manifold, or use
an onsite acetylene generator (available with sustained flows up
to about 100 cu ft an hour). Or for cutting and heating only, you
can switch to propane fuel gas (with the proper propane tips and
*all fuel* rated hoses).
Reading the charts is a good exercise for those thinking of using
small tanks such as a MC or B tank. A MC tank (10 cu ft) won't
even properly feed a 00 tip (1/16th inch welding capacity), and
really should be limited to a 000 tip (1/32 welding capacity). The
B size tank (40 cu ft) can just barely feed a #2 tip, but really
should be limited to a #1 (3/32 welding capacity).
The golden rule of acetylene tank safety is that no matter what
size tank you have, it should take 7 hours to empty it at sustained
draw. So if you're emptying a tank quicker than that, you're in
dangerous territory and need to switch to a smaller tip (or a bigger