Which type of flowmeter must be oriented in a vertical position?

The rotameter is designed to measure the flow rate of liquids and gases, and it operates based on the principle of variable area flow measurement. It consists of a tapered tube and a float that rises and falls within the tube based on the flow rate.

For accurate measurement, a rotameter must be oriented vertically. This vertical orientation ensures that the float can move freely without obstruction and that the gravitational force acts uniformly on it. If a rotameter is installed horizontally, the float may not stabilize at the correct position corresponding to the flow rate, leading to inaccurate readings or even potential damage.

Other flowmeter types, such as turbine, piston, and vane flowmeters, can typically be installed in a variety of orientations without significantly affecting their performance or accuracy. However, the unique design and operational characteristics of the rotameter make its vertical orientation essential for reliable flow measurement.