Project input form
Enter cylinder data, welding cycle values, and planning allowances. Results appear above this form after submission.
Example data table
| Scenario | Process | Flow Rate | Arc Minutes | Total Gas | Likely Cylinders |
|---|---|---|---|---|---|
| Handrail fabrication | MIG / GMAW | 18 L/min | 120 min | 2,550 L | 1 |
| Pipe spool welding | TIG / GTAW | 12 L/min | 210 min | 2,980 L | 1 |
| Structural repair package | FCAW-G | 22 L/min | 300 min | 7,240 L | 1 |
| Pipe purge campaign | Pipe Purge Only | 14 L/min | 0 min | 1,470 L | 1 |
These values are illustrative. Actual demand depends on regulator setting, line condition, ambient temperature, and field handling losses.
Formula used
- Usable gas per cylinder = Cylinder water capacity × (Fill pressure − Residual pressure) × (288.15 ÷ Ambient temperature in kelvin) × Utilization efficiency
- Active welding gas = Flow rate × Total arc minutes × Simultaneous torches
- Pre/post flow gas = Flow rate × ((Preflow + Postflow) ÷ 60) × Number of welds × Simultaneous torches
- Purge gas = Flow rate × (Purge time ÷ 60) × Setup events
- Loss-adjusted gas = (Active welding gas + Pre/post flow gas + Purge gas) × (1 + Leak loss %)
- Total required gas = Loss-adjusted gas × (1 + Reserve %)
- Cylinders needed = Ceiling(Total required gas ÷ Usable gas per cylinder)
How to use this calculator
- Choose the welding process and shielding gas used on site.
- Enter cylinder water capacity, fill pressure, and the minimum residual pressure you want to keep.
- Input the regulator flow rate, expected arc time per weld, and the total number of welds.
- Add preflow, postflow, purge duration, and setup events to capture non-arc gas demand.
- Include simultaneous torches, expected losses, reserve allowance, ambient temperature, and refill cost.
- Submit the form and review total gas requirement, cylinder count, runtime, cost, and the Plotly breakdown above the form.
FAQs
1) What flow rate should I enter?
Enter the actual regulator setting used during welding or purge work. Typical values are often 10 to 14 L/min for TIG and 15 to 22 L/min for MIG, but field drafts, nozzle size, and procedure requirements can change the correct setting.
2) Why does the calculator ask for residual pressure?
Residual pressure protects the cylinder, avoids drawing it completely flat, and reflects real-world practice. Keeping some pressure also helps maintain stable flow near the end of the bottle and prevents unrealistic estimates of usable gas volume.
3) Does this work for multiple welders on one supply?
Yes. Increase the simultaneous torch count when more than one torch is drawing from the same source at the same time. That reduces runtime per cylinder and increases the total gas volume required for the job.
4) Why are preflow, postflow, and purge included?
Many gas estimates miss these losses. On short welds or frequent starts, non-arc flow can become a large share of total consumption. Including them makes planning more realistic, especially for pipe fabrication and stop-start site work.
5) How accurate is the temperature correction?
It is a planning approximation based on gas-law behavior. It helps compare cold and hot conditions, but actual cylinder performance also depends on regulator condition, fill quality, hose leakage, and the practical pressure you can still use on site.
6) Can I use this for purge-only jobs?
Yes. Select the purge-only process option. The calculator then ignores arc-related gas and estimates total demand from purge time, setup events, losses, reserve allowance, cylinder capacity, and refill planning.
7) Why do cylinders last less time in the field than expected?
Common causes are higher real flow than the gauge shows, leaky fittings, excessive purge time, windy conditions, damaged hoses, and unplanned starts. Adding a realistic loss percentage and reserve margin helps your estimate match actual site behavior.
8) Should I estimate from shift time or arc time?
Use arc time for the welding portion whenever possible. Shift time usually overstates gas demand unless you convert it into realistic arc-on duty. Then add preflow, postflow, purging, and losses separately for a better total.