The rate of flow is measured in which units?

• A. Bar
• B. cubic feet per hour or liters per minute
• C. Pounds per square inch
• D. Gallons per day

Answer: (B)

The rate of flow is about how much gas or liquid moves through a system per unit of time. In welding, this is typically expressed as volume per time, such as cubic feet per hour or liters per minute. These units directly quantify how much material is passing a point each minute or hour, which is essential for controlling shielding gas and other flow-dependent processes.

Units like bar or pounds per square inch measure pressure, not how much is flowing, so they don’t describe flow rate. Gallons per day is a volume-per-time measure, but it’s not practical for the precise, real-time control required in welding; you’d usually use CFH or L/min instead.