700W Fiber laser cutter - How many bottles of gas?

[Alex Smith23]

I recently purchased a 700W fiber laser cutter and my seller said I need to purchase 10 tanks each of oxygen and nitrogen so I'll have plenty of gas when the engineer comes out to set up my machine. Seems a little excessive (and expensive!) and was wondering how many bottles other fiber laser owners have purchased to get them up and running.

[Bill George]

Your going to have maybe $2000 or $3000 in tanks alone.

[Michael Henriksen]

I spent 1.5 days with the engineer and we cut a variety of sheet thicknesses in steel, stainless and brass. Used very little oxygen and less than 1/4 bottle of nitrogen. These are 50L bottles. 10 bottles of nitrogen is more than a full days worth of cutting. You don't use nearly as much oxygen as nitrogen. I rent the bottles but actually don't pay any rent - just pay for the gas I use. When you start up production in earnest it's well worth getting 10 bottle batteries of nitrogen. The cost per cubic meter is a lot less this way. I use nitrogen for cutting stainless but also for mild steel below 2mm - cuts faster and there is no burn back. My machine has a 1kW source.

[Alex Smith23]

I spent 1.5 days with the engineer and we cut a variety of sheet thicknesses in steel, stainless and brass. Used very little oxygen and less than 1/4 bottle of nitrogen. These are 50L bottles. 10 bottles of nitrogen is more than a full days worth of cutting. You don't use nearly as much oxygen as nitrogen. I rent the bottles but actually don't pay any rent - just pay for the gas I use. When you start up production in earnest it's well worth getting 10 bottle batteries of nitrogen. The cost per cubic meter is a lot less this way. I use nitrogen for cutting stainless but also for mild steel below 2mm - cuts faster and there is no burn back. My machine has a 1kW source.

Michael, thank you for the info! I'm new to the whole gas thing, so when you say a 50L bottle is it similar to the tank with 55 under it on this link? (http://www.airgas.com/product/Gases/Industrial-Application-Gases/Nitrogen---Industrial/p/NI%20300) I was told to get a tank similar to the picture where it has 300 under it.

Do you mind me asking where you rent your gas from and a ballpark price of nitrogen or oxygen? I stopped by Praxair air yesterday and the rep said to buy a tank it's $275 and the gas is about $45.

[Tony South]

You can also look at Airgas. thats where we get nitrogen for laser welding.

[Kev Williams]

disclaimer, my source of information is one customer and one vendor with laser cutters, but both have told me that an issue with nitrogen is you must use it quick or it 'goes away' -- dissipates, evaporates-? My customer bought a used 4000w C02 cutter and it came with a 300 gallon(?) -ish size nitrogen container. After filling it, they used it for testing, found they had to do $20,000 worth of repairs & maintenance to the cutter, and a month later they found they had no nitrogen. My vendor (sheet metal shop) has told me similar stories.

So, you guys using nitrogen, have you found the same to be true? My biz associates both use LARGE tanks, would the smaller tanks do a better job of sealing?

[Chris Thomason]

Kev,

Your customer may be talking about liquid nitrogen. It’s normally cheaper than gas if you use large amounts every month but it does self vent to avoid over pressurization. I have never heard of nitrogen gas bottles needing to vent under normal situations but I am no expert.

I believe the OP is talking about normal welding tanks full of nitrogen gas. If you have a forklift you may want to get them in 6 packs so you don’t have to haul tanks around by hand. My suggestion is to call a couple local welding suppliers and talk to them about your needs. My guess is you use enough gas they will rent you the bottles for free.

[Michael Henriksen]

Sorry, not familiar with US bottle sizes. A 50L bottle is the biggest we can get in Denmark. Weighs 67kg when full. Holds app. 10cbm nitrogen. Cost $38 for a refill and they charge me no rent. These bottles don't vent so I don't see how they could be losing gas.

[Bill George]

Sorry, not familiar with US bottle sizes. A 50L bottle is the biggest we can get in Denmark. Weighs 67kg when full. Holds app. 10cbm nitrogen. Cost $38 for a refill and they charge me no rent. These bottles don't vent so I don't see how they could be losing gas.

Some gases do not hold for long in a steel cylinder. Believe it or not. Helium, Hydrogen are the two I can think of right off hand. May be more I am sure. No it will not go away overnight but over a few months. They are lining some of the newer tanks.

[Kev Williams]

YES to the LIQUID nitrogen, didn't think about that, or that the small tanks wouldn't also be liquid filled...

I have a 30 gallon propane tank parked in the one corner where our chimney meets the house to feed our fireplace gas log, tank's about 4' tall, 15" or so diameter, I assume a 50L tank is about half that size? And still weighs 145-ish pounds when full? Interesting...

[Scott Marquez]

Kev,

Your customer may be talking about liquid nitrogen. It’s normally cheaper than gas if you use large amounts every month but it does self vent to avoid over pressurization. I have never heard of nitrogen gas bottles needing to vent under normal situations but I am no expert.

I believe the OP is talking about normal welding tanks full of nitrogen gas. If you have a forklift you may want to get them in 6 packs so you don’t have to haul tanks around by hand. My suggestion is to call a couple local welding suppliers and talk to them about your needs. My guess is you use enough gas they will rent you the bottles for free.

Like Chris said, contact your local welding supplier and have them help get you up and running. They “want” your business.
My day job is outside sales for a welding supplier.
I service a small rural area and don’t have any laser customers, but I have heard the term “laser packs” which I believe are designed to meet the high flow rates of Nitrogen.
Im interested in hearing how this comes out.
Scott