What device is used for leak testing of gas piping within a structure?

The use of a manometer for leak testing of gas piping is particularly important due to its ability to measure low pressures accurately. In plumbing and gas piping systems, it's crucial to ensure that there are no leaks to prevent hazardous situations, such as gas leaks that can lead to explosions or poisoning. A manometer measures the pressure difference and can detect changes in pressure that indicate a leak. When testing gas piping, the system is typically pressurized, and the manometer helps determine if there's a drop in pressure that exceeds allowable limits, signaling a potential leak.

In contrast, a pressure gauge might not provide the necessary precision for low-pressure applications commonly seen in gas systems. A flow meter measures the rate of flow of gas but does not indicate if there’s a leak in the system. A thermometer, while useful in determining temperature, does not provide information about pressure changes or leaks. Thus, the manometer is the most suitable device for effectively detecting leaks in gas piping systems within structures.