What device is often used to measure fluid pressure?

The device that is commonly used to measure fluid pressure is the manometer. A manometer is specifically designed to measure the pressure of gases or liquids. It compares the pressure of the fluid in question to a reference pressure, such as atmospheric pressure. This is typically accomplished through the use of a column of liquid and can take various forms, including a U-tube manometer, which allows for a visual gauge of pressure differences based on the height of the liquid in each side of the tube. This specificity makes manometers essential instruments in various applications, particularly in fields such as physics, engineering, and chemistry, where knowing precise fluid pressure is crucial for experiments and processes.

In contrast, while a barometer is indeed used to measure pressure, it is primarily designed to measure atmospheric pressure rather than the pressure of fluids in pipes or tanks. A thermometer measures temperature, which is unrelated to pressure measurements. An accelerometer, on the other hand, is a device that measures acceleration rather than pressure, making it unsuitable for this particular context. Therefore, among the given options, the manometer is the most appropriate choice for measuring fluid pressure.