What device controls the flow of shielding gas in GMAW?

In the context of Gas Metal Arc Welding (GMAW), the device that is responsible for controlling the flow of shielding gas is the flowmeter. A flowmeter accurately measures and regulates the rate at which the shielding gas is delivered to the welding gun. This is vital because the correct rate of gas flow is essential for shielding the weld pool from contamination and atmospheric interference, ensuring high-quality welds.

The flowmeter works in conjunction with the gas regulator, which is primarily responsible for reducing the pressure of the gas from the cylinder to a usable level. While the gas regulator is important and often placed before the flowmeter in the gas supply line, it does not directly control the flow rate; that is the role of the flowmeter itself. The welding gun, although it is where the gas is delivered and mixed with the welding wire, does not control the flow. The power supply provides the necessary electrical current for the arc but does not deal with gas flow whatsoever. Thus, the flowmeter is the key component specifically designated for controlling the shielding gas flow in GMAW.