Calculating Nitrogen Comsumption

[mrieder]

Having a difficult time calculating the nitrogen consumption and cost while laser cutting aluminum on a fiber laser. The formula I have just isn't matching the expense we are incurring to fill up our nitrogen bulk tank. Please help!

 

[LASERNINJA]

First problem is you are assuming the gas company is ethical.

Next, I think foostrap made a post with a pretty good formula. A bit more searching and you might be able to find it.

Last. It's complicated. Not like man on the moon complicated, but none the less. Obviously, nozzle size, pressure are the primary variables. Nozzle gap, focus, and temperature contribute to the equation as well.

Best bet would be to get a nitrogen six pack in there and see how long that lasts. You can then extrapolate your consumption from hard data.

 

[mrieder]

I actually did come across foostrap's formula, and used it to calculate the cubic ft/hr. On previous jobs we did use the nitrogen six packs, but have since put in a nitrogen bulk tank. We have been using hard data while running the job, but would like to have a formula for quoting purposes. Any suggestions?

 

[SGAFFNEY]

Another (BIG) thing to consider is that there is always product loss due to pressure building up as the liquid changes to gas. It will be worse in the summer with the temperature elevation. Another cost factor is how often you receive deliveries of N2. Have you ever watched and listened while the delivery is happening. You are paying for the loss that occurs. Talk to your gas company about these issues and see if they will provide decent info to help with your calculations. I would look at the hard data and make up my own formula based on your actual usage. You know what you are paying. Keep track of how many hours of N2 cutting between billing cycles and then you can create a sliding scale based on thickness (thicker uses larger nozzles and higher pressures.)To get good info from the gas company you may have to go up the ladder and talk to multiple people. Start with the driver, then the outside salesman and if necessary contact the branch manager.