LS20B Propeller Current Meter: Measurement Principle and Usage

LS20B propeller current meter is a general-purpose hydrological instrument used for rivers, lakes, reservoirs, and canals. It consists of a propeller-type current sensor, a current meter, and a measuring rod. Connecting a signal line allows for automatic measurement and display of the average flow velocity over a given period in open channels. This instrument conforms to the national standard GB/T 11826-2019 and is suitable for flow velocity and flow monitoring in industries such as water conservancy surveys, farmland irrigation, runoff experiments, and environmental protection and mining.

LS20B propeller current meter is designed based on the velocity-area method principle of open channel flow measurement, a commonly used measurement method in hydrological surveys. The instrument consists of three parts: a propeller-type current sensor, a current meter, and a measuring rod. The entire set of equipment is housed in an aluminum alloy combination lock case for easy portability and field deployment.

The instrument operates by the water flow driving the propeller to rotate. The built-in magnet and reed switch electronic switch output two signals per revolution. After receiving the signal, the flow velocity meter automatically calculates the average flow velocity over a given period using the formula V=KN/T+C. The instrument's velocity measurement range is from 0.04 m/s to 15 m/s, covering water flow environments from low to high speeds.

In practical use, first remove the flow velocity sensor, meter, and measuring rod from the aluminum alloy case. Assemble and fix the sensor to the measuring rod, and connect it to the flow velocity meter via a signal cable. Select a suitable measurement position on the measuring rod, ensuring the sensor faces the direction of the water flow. Turn on the meter's power, set the flow time, and place the sensor at the predetermined measurement point in the water. The meter will automatically count and display the flow velocity value. The instrument supports both rod positioning and cable suspension installation methods, suitable for measurement needs under different water depths and cross-sectional conditions.

This instrument has been tested in practical applications in high-sediment-content rivers such as the Yellow River. Under high-speed, high-sediment-content conditions, the sealing performance of the bearing oil chamber can maintain stable operation for a flood season without disassembly and cleaning. The propeller is made of engineering plastics, which provides geometric stability and aging resistance, ensuring its calibration coefficient remains stable even under prolonged outdoor operation. The instrument can also be connected to a computer, transmitting flow measurement data directly to a host computer for recording and processing via a communication interface.