Which of the following types of valves is used to control gas flow and can be found in gas piping systems?

Ball valves are designed specifically for controlling gas flow within piping systems. They feature a spherical disc that rotates with a quarter-turn, allowing for quick and precise on/off control. This makes them particularly effective in applications where fast shut-off is needed, such as in gas piping.

The construction of a ball valve allows it to provide a tight seal when closed, preventing any gas leakage. The smooth surface of the ball ensures that there is minimal resistance to flow when the valve is open, maximizing efficiency.

While gate valves may also control flow, they typically require multiple turns to open or close, making them less suitable for applications where immediate control is essential. Relief valves, on the other hand, are used to release excess pressure and are not designed for flow control, while check valves primarily allow flow in one direction to prevent backflow but do not control the flow rate. This specificity to flow control in gas systems distinguishes ball valves as the most appropriate choice.