What is commonly used to measure pressure differences in boilers?

A manometer is commonly used to measure pressure differences in boilers because it is designed specifically for this purpose. Manometers typically consist of a U-shaped tube filled with liquid, usually mercury or water. When there is a pressure difference between the two sides of the U-tube, the liquid levels in the arms of the tube change, allowing the user to determine the pressure difference by measuring the height variation.

This tool is particularly useful in boiler applications because it provides a direct and precise measurement of pressure differentials, which are crucial for safe and efficient boiler operation. Understanding these pressure differentials helps operators assess the performance of the system and ensure that it operates within specified limits, preventing issues like overpressure or vacuum conditions.

The other choices do not serve the same function as effectively in measuring pressure differences. Pressure gauges measure absolute pressure rather than pressure differentials. Thermometers are used to measure temperature, and flow meters measure the flow rate of liquids or gases. Each of these instruments has its specific application, but for measuring pressure differences, the manometer is the most suitable tool.