What is the purpose of a sounding tube?

The function of a sounding tube is specifically designed to determine the liquid level within a tank or vessel. This device extends vertically into the tank and provides a way to measure the height of the liquid. By using a sounding tube, operators can ascertain the volume of liquid present, which is crucial for various operational and safety considerations in engineering and industrial applications. This measurement can help in inventory management, process control, and ensuring that tanks are not overfilled or run dry.

The other options pertain to different measurement techniques and devices: measuring air pressure requires specific pressure sensors or gauges, checking for leaks typically involves inspection methods or tools such as pressure testing or vacuum testing, and temperature measurement employs thermometers or thermocouples. Each of these functions is distinct and does not overlap with the primary role of a sounding tube.