The HUALIU HL-LZS plastic-tube rotameter is a variable-area (float-type) flow instrument whose main components, including the tapered tube, are made of AS and ABS engineering plastics, offering good corrosion resistance. It combines a sensible structure, small size, light weight and a shatter-resistant tapered tube, making it an economical and practical local-indication flowmeter, widely used for liquid and gas flow measurement in the chemical, environmental-protection, food and other industrial sectors.

The instrument uses as its measuring elements a transparent plastic tapered tube installed vertically with the small end down and the large end up, together with a float that can move up and down inside the tube, and is completed with nuts, connecting pipes, stops and O-ring seals. When the measured fluid flows upward through the tapered tube, a pressure difference is created above and below the float that pushes it upward; when this differential pressure balances the float's gravity, buoyancy and viscous force, the float stabilizes at a certain height. A change in flow causes a corresponding change in the annular-gap flow velocity and differential pressure between the tapered tube and the float, and the float moves up or down accordingly; therefore the rest height of the float serves as a measure of flow. The measuring range, calibration dimensions and tube material are all marked on the measuring tube for direct on-site reading.

The product offers various connection types such as plug-in, welded, threaded and flanged to suit the installation needs of different pipelines. Its wear- and corrosion-resistant plastic structure makes it especially suitable for clean fluids and moderately corrosive media, making it the entry-level choice in the HUALIU variable-area flow series that balances cost-effectiveness and reliability.