in oxyfuel cutting, using acetylene which cylinder empties first oxigen or acetylene?

Question

according to your experience, how many inches can I make with a common pair of cylinders?

or how often acetylen cylinders should be refilled according to the jobs you have performed?

I know it's difficult to measure gas,

Answer 1

It depends on the work you are doing, the degree of oxidation you set up in your flame and the size of the tanks. A small welding set has two identically sized tanks. The most common tanks the O2 tank is taller and the acetylene tank is fatter.
As for inches, are you using a 00, 0, 1, or 2 tip? Of course the size of the tip is related to the thickness of the metal. Of course, if you do any cutting that uses up O2 very rapidly.

Answer 2

You might be better off asking this question in one of the other sections. It's not likely you'll find many engineers with welding experience. At least not enough to have consumed whole bottles of acetylene and oxygen, let alone be able to relate it to a number of jobs or inches of welding/cutting.

The other thing is that this is relative to bottle size and what you are welding or cutting. Even if you do get an answer be sure to be able to relate it to the size of bottle that the person generally used.

As a final though, you might be able to contact your local welding supply store. Most of the time, they have first hand experience and can point you in the right direction. They also are more willing to help you since they will want you as a potential customer.