Consumables, time and cost
Shielding gas usage and cylinders
- where
- gas used (m³)
- gas flow rate (l/min)
- arc-on time (h)
- allowance for pre-flow, post-flow and purging (%)
- cylinders used
- gas content of one cylinder (m³)
Explain this equation
Estimates the shielding gas a job will use and how many cylinders that is.
Flow is set in litres per minute, so times 60 gives litres per hour, and times the arc-on hours gives litres while welding. Gas also flows before and after each weld and for purging, which the allowance covers. Dividing by 1000 gives cubic metres, the unit cylinders are sold in.
Volume equals flow rate times time.
Sense check: 15 l/min for 10 hours of arc time with 10% extra is about 9.9 m³, most of one large argon-mix cylinder.
Watch out: leaking hoses and fittings, and flow set too high, often waste more gas than the welding uses. Check the flow at the torch.
Estimates the shielding gas used for a job from the flowmeter setting and arc-on time, and how many cylinders that is.
Enter your values to see the result.
Good to know
Flow rates are typically about 8–12 l/min on thin sheet and 15–20 l/min on thicker plate; helium mixtures and draughty sites need more. Cylinder contents are on the label or supplier data (BOC argon: X 2.36, Y 4.72, W 11.01, E50 15.14 m³). Get arc-on time from the arc time calculator.
Common mistake
Multiplying flow by the whole shift. Gas only flows while the trigger is pulled (plus pre- and post-flow), so use arc-on time.
Limits
Ignores leaks, which can be significant on worn hoses and fittings. Mixed-gas cylinder contents differ from pure argon; check the label.
Sources
Results are calculations from the published methods and figures shown, and depend on the data you enter. Follow the welding procedure specification (WPS), BS EN ISO 15614/9606, BS EN 1090, BS EN 1993 and manufacturers’ data. Structural welds need qualified welders and engineered designs.