Assist Gas Cost & Selection Guide
Choose the right assist gas for your application and optimize costs
Reference data governance
Last reviewed: 2026-04-27. Gas cost and flow inputs come from supplier quotes and shop measurements; replace every placeholder with delivered gas contract terms, generator proposal data, and measured flow before quoting.
Review methodology and assumptionsOxygen (O2)
Best For:
Mild steel, carbon steel
Advantages:
- Can enable higher cutting speeds in many setups
- Unit gas cost should be taken from your delivered gas contract
- Exothermic reaction adds heat
Disadvantages:
- Oxidized (black) edges
- Not suitable for stainless/aluminum
- Requires post-processing for painted parts
Nitrogen (N2)
Best For:
Stainless steel, aluminum, brass, copper
Advantages:
- Clean, oxide-free edges
- Often reduces or removes post-processing
- Suitable for painted/coated parts
Disadvantages:
- Unit cost depends on cylinder, bulk, or generator contract terms
- May require slower feeds than O2 at similar edge quality
- Pressure should follow the machine cut chart and quality requirement
Air (Compressed)
Best For:
Thin mild steel (<3 mm), general purpose
Advantages:
- Lowest cost (compressor only)
- Suitable for non-critical parts
- No gas supply needed
Disadvantages:
- Limited thickness capability
- Moderate edge quality
- Requires oil-free compressor
Cost Comparison by Application
| Application | Recommended Gas | Cost Input | Notes |
|---|---|---|---|
| Mild Steel (structural) | Oxygen | Supplier quote | Compare speed, edge oxidation, and post-processing |
| Mild Steel (for painting) | Nitrogen | Supplier quote | Use when the edge requirement justifies the gas cost |
| Stainless Steel | Nitrogen | Supplier quote | Confirm purity, pressure, and edge requirement |
| Aluminum | Nitrogen | Supplier quote | Confirm machine support and sample-cut quality |
| Thin sheets (<3 mm) | Air | Compressor data | Use oil-free air where the machine requires it |
Use the table as a routing checklist only. Gas cost needs your supplier quote, cylinder rental or bulk terms, delivery fees, generator proposal, measured flow, and active cutting time.
On-Site Nitrogen Generation Review
Build the purchase case from supplier-backed and measured inputs.
Bottled Nitrogen Costs
Generator Investment
Purchase review: Treat generator decisions as a shop-specific model. Collect nitrogen cutting hours, delivered gas contract terms, electricity tariff, maintenance plan, financing terms, floor-space constraints, and a vendor proposal before comparing bottled supply with on-site generation.
Flow & Pressure Reference
Keep conversion factors handy when translating supplier data.
Common conversions
- 1 bar = 14.5 psi (12 bar nitrogen = 174 psi).
- m3/hr = SCFH x 0.472; SCFH = m3/hr x 2.12.
- kg/cm2 roughly equals bar for quick mental math.
Validate flow references when comparing European spec sheets to US pricing.
Setup checklist
- Log gas purity (99.5%+ for stainless) and dew point (-40 C or better).
- Confirm regulator Cv and hose ID match the required flow rate.
- Record nozzle size/focus inside your processing parameter sheet for repeatability.
Gas Cost Optimization Tips
1. Choose the Right Gas for Each Job
Do not use expensive nitrogen when oxygen will work. For structural mild steel parts that will be painted, the oxidized edge gets covered anyway. Save nitrogen for stainless, aluminum, and parts requiring clean edges.
2. Optimize Gas Pressure
Excessive pressure can waste gas without improving cut quality. Start from your machine or supplier recommended pressure, then adjust in small steps while checking edge quality and cut stability. Use flow meters or supplier guidance to understand how changes in pressure affect actual gas use for your setup.
3. Fix Leaks Promptly
Even small leaks in your gas system can accumulate into meaningful annual cost. Check connections regularly with leak detection spray and use your own gas pricing to estimate the financial impact. Common leak points include quick disconnects, regulators, and nozzle seals.
4. Consider Bulk Gas Delivery
If your nitrogen consumption is consistently high, bulk liquid delivery may offer lower unit pricing than high-pressure cylinders. Discuss volume tiers, tank requirements, and long-term pricing with your gas supplier using your own delivery history and usage records.
5. Use Air for Non-Critical Parts
For thin mild steel prototype parts, test pieces, or internal brackets, compressed air can provide acceptable quality at minimal cost. Invest in an oil-free compressor with adequate CFM.
Cost Workflow Checklist
Tie gas pricing to the calculators so every quote reflects real consumption.
- 1. Capture contract pricing. Store cylinder rental, delivery fees, purity, and pressure requirements inside your sourcing log so operators and estimators share the same assumptions.
- 2. Calculate gas consumption. Feed flow (m3/hr), active cutting time, pierce time, and price per m3 into the Gas Consumption calculator before rolling the result into shop-rate or quote math.
- 3. Push per-part cost downstream. Apply the hourly gas cost inside the Laser Cutting calculator or Price per Meter tool so final quotes show true margin impact.