Multiply the water capacity in liters by the pressure in bar: a 20-liter cylinder at 200 bar contains about 4,000 liters of gas. At a typical MIG flow of 10 l/min that is about 400 minutes of arc time — six or seven hours.
Most people are surprised how fast that goes, and equally surprised how much is lost to leaks rather than welding. A joint that bubbles under soapy water empties a cylinder overnight without a sound.
The questions welders ask
Should I buy or rent a cylinder?
Renting carries a standing charge whether you weld or not, which suits high usage. Owned refillable cylinders cost more up front and nothing to keep. Disposable cylinders are convenient, cost several times as much per liter and run out mid-weld — they are a way to start, not a way to continue.
Last reviewed 2026-08-14