Does a nitrogen generator pay for itself?
Updated:
Short answer
It depends on hours cut per week and cylinder price, not on machine power. A shop running stainless several shifts a day on cylinder nitrogen often recovers a mid-size generator in one to two years; a shop cutting nitrogen only occasionally rarely breaks even.
What decides the payback
| Symptom | Likely cause | First action |
|---|---|---|
| High weekly nitrogen hours on stainless or aluminium. | Cylinder or bulk-tank nitrogen carries a per-m³ markup that a generator removes. | Log actual m³/h from the nozzle table, multiply by weekly cutting hours — this is the number that matters, not machine rating. |
| Nitrogen used only for a handful of jobs a month. | Fixed generator cost (purchase, install, membrane replacement) outweighs the saving at low volume. | Stay on cylinders; revisit the calculation if nitrogen work grows. |
| Purity requirement above 99.95%. | High-purity generation needs a larger, more expensive unit than bulk 99% nitrogen. | Confirm the purity your parts actually need before sizing the generator — over-specifying inflates payback time. |
| Thick-plate nitrogen work at high pressure. | High pressure demands higher generator flow capacity, the main cost driver of the unit itself. | Size the generator to peak flow (nozzle × pressure), not average — undersizing forces a fallback to cylinders anyway. |
Run your real m³/h and gas price through the calculator — inside the app. Open SBM Laser Help →
Or take it with you:
A rough payback check
- Estimate weekly nitrogen consumption in m³ from your nozzle and pressure (see the nitrogen consumption page).
- Multiply by your cylinder or bulk price per m³ to get the current weekly gas bill.
- Compare against the generator’s purchase, installation and membrane/maintenance cost spread over its expected life.
- If the weekly saving pays back the unit in under two years at your real utilisation, it is usually worth pricing seriously.
Related questions
- Can a generator reach the purity nitrogen cutting needs?
- Membrane generators comfortably reach 99.5–99.9%; PSA units can push higher. For most stainless work, 99.95%+ needs a properly sized PSA system, not the smallest membrane unit on the market.
- Does a generator affect cutting quality?
- Not if it is sized and maintained correctly — the gas at the nozzle is what matters, and a well-run generator supplies the same spec as a cylinder.
- What is the hidden cost people forget?
- Compressed air supply for the generator, membrane or PSA media replacement on schedule, and floor space — all small individually, but they change the payback math if left out.