The metal tube rotameter (also known as the variable area flowmeter) is a flow instrument based on the variable area measurement principle, mainly used for continuously measuring the instantaneous flow of liquids, gases, or steam. Its core feature is the use of a metal tube body, making it suitable for harsh working conditions such as high – temperature, high – pressure, and corrosive media.

Working Principle

1. Structural Components

• Conical metal tube: Designed with an inverted conical interior.
• Float: An internally – placed magnetic float that moves up and down with changes in flow rate.
• Indicator: Converts the position of the float into a flow reading through a magnetic coupling system (can be equipped with a remote – transmission signal output).

2. Working Process

When the fluid passes through the conical tube from bottom to top, the float suspends under the balance of fluid dynamic force and gravity. When the flow rate increases, the float rises, and the annular flow area increases until a new equilibrium position is reached. The position of the float has a linear relationship with the flow rate.