A __ controls the flow of gas at the welding?

• A. Cylinder valve
• B. Manifold system
• C. Needle valve
• D. Regulator

Answer: (C)

Controlling the shielding gas flow at the welding arc is done by a needle valve. The needle valve uses a small, tapered needle that moves into or out of a matching seat to throttle the gas precisely. Because the arc and weld quality depend on consistent shielding, this fine adjustment is essential—the slightest turn can significantly change the flow rate, giving stable gas coverage around the weld.

Other components have different roles: the cylinder valve simply opens or closes the gas from the cylinder, the regulator lowers the cylinder pressure to a usable level and helps maintain a steady pressure, and the manifold system distributes gas to multiple outlets but does not provide the fine, at-the-arc flow control.