Which of the following is a common type of pressure gauge?

A common type of pressure gauge is the metal bellows gauge. This type of gauge operates based on the movement of a flexible metal bellows that expands or contracts in response to the pressure of the fluid or gas being measured. As the bellows moves, it translates this motion into a reading on a dial or scale, allowing operators to easily quantify the pressure.

Metal bellows gauges are known for their accuracy and reliability, making them a frequent choice in various applications, including water and wastewater treatment processes. They are especially useful in situations where a mechanical, analog representation of pressure is needed.

While digital sensors are also used widely in pressure measurement, they are more modern technology and not as traditional a type as the metal bellows. Hydrostatic gauges rely on the weight of a fluid to measure pressure rather than a direct mechanical movement. Ultrasonic gauges utilize sound waves to measure pressure and are different in mechanism and application context compared to mechanical gauges. The choice of a pressure measurement technique often depends on the specific requirements of the system in terms of accuracy, the environment, and the nature of the fluid being measured.