UV Curing calculator

UV Nitrogen Consumption Calculator

Some UV chemistries (acrylates especially) cure poorly in air because oxygen inhibits surface free-radical polymerization, leaving a tacky surface. The fix is a nitrogen-inerted cure tunnel that displaces O₂ to <500 ppm. Nitrogen isn't free — at industrial flow rates, the bill is real. This calculator turns tunnel SCFH and on-time into an hourly cost so the consumable shows up in the line economics.

What this calculator does

  • Calculate nitrogen consumption (SCFH) and hourly cost for inerted UV cure tunnels — the alternative to oxygen inhibition on surface-cure-sensitive chemistries.
  • Use it when costing inerted vs non-inerted cure on a new line, or when nitrogen cost is a meaningful share of cure operating cost.
  • Reports nitrogen consumption (scf/hr) and hourly cost ($/hr) for inerted UV cure tunnels.

Formula used

  • Hourly consumption (scf/hr) = flow rate × runtime fraction
  • Hourly cost = consumption × $/scf

Inputs explained

  • Nitrogen flow rate: From the inerting tunnel data sheet — typical 50–500 SCFH depending on tunnel length and seals.
  • Runtime per hour: Fraction of the hour the tunnel is producing; idle periods may be lower flow.
  • Nitrogen unit cost: From the gas vendor — bulk liquid N₂ ~$0.005–0.015/scf; high-purity bottled higher.

How to use the result

  • Use it when costing inerted vs non-inerted cure for a new line, when nitrogen is a meaningful operating-cost line, and when sizing a bulk N₂ tank for a new cell.
  • Doesn't model O₂ ppm achieved — that depends on tunnel design and seal quality. Some tunnels need 2× the spec'd flow to hit <500 ppm O₂ in real use; verify with an O₂ analyzer before sizing the gas supply contract.

Common questions

  • When is nitrogen inerting necessary? On surface-sensitive UV chemistries (especially clear coats, low-pigment formulations, and matte / haptic finishes) where the top 1–10 microns can't cure in air. Vendor data sheets call out 'inerting required' or specify a max O₂ ppm. Pigmented inks usually don't need inerting because pigment shields the photoinitiator.
  • What's the alternative to nitrogen? Three: (1) cationic UV chemistry (no oxygen inhibition by mechanism); (2) reformulate to amine-modified or HALS-modified acrylate (chemistry workaround); (3) thicker / pigmented coatings where oxygen inhibits only the top fraction of a thicker film. Each has trade-offs — nitrogen is often the lowest-effort answer.
  • How do I size the nitrogen supply? Hourly consumption from this calc × hours per shift × shifts per week × 1.5 safety = weekly demand. Above ~50,000 scf/wk, bulk liquid is cheaper than bottled. Above ~200,000 scf/wk, on-site generation (PSA or membrane) typically wins on payback. Talk to your gas vendor with this number in hand.
  • Why include the runtime fraction? Many tunnels reduce flow to a low purge during idle (no production) and ramp up to full flow during production. Setting runtime = 1.0 assumes always-on full flow — that overstates cost for lines with long idle periods. Use the actual production-time fraction.

Last reviewed 2026-05-12.