What is the purpose of a differential pressure gauge in a liquid system?

The purpose of a differential pressure gauge in a liquid system is to measure pressure differentials. This type of gauge is designed specifically to compare two pressures, typically across a particular section of a system, such as across a filter or a piping system. By measuring the difference in pressure between two points, it helps in monitoring the performance and condition of equipment, allowing for the detection of issues such as clogging or excessive wear. This measurement is crucial for maintaining system efficiency and preventing potential failure within the system.

The other options do not align with the primary function of a differential pressure gauge. While fluid temperature and flow rate are critical parameters in a liquid system, those measurements require different instruments, such as thermometers and flow meters, respectively. Indicating fluid density is also a separate function that does not relate to pressure measurement; this typically involves devices like hydrometers or densitometers. Thus, the focus of a differential pressure gauge is specifically on the measurement of pressure differentials, leading to better analysis and management of the liquid system.