Float tube flowmeter, also known as rotameter, is a kind of variable area flowmeter. In a vertical cone tube that expands from bottom to top, the gravity of a float with a circular cross section is received by liquid power, and the float can move in Rise and fall freely in the cone tube. It moves up and down under the action of flow velocity and buoyancy, and after being balanced with the weight of the float, it passes through the magnetic coupling to indicate the flow with the dial. Generally divided into glass and metal rotameter. Metal rotor flowmeters are commonly used in the industry. For small diameter corrosive media, glass is usually used. Due to the fragility of glass material, the key control point is also a rotor flowmeter made of precious metals such as titanium.