LJ12 Series Propeller-Type Current Meter

1. Product Introduction

This series of propeller-type current meters features a compact design, light weight, and portability, making them suitable for use in small rivers, channels, runoff experimental stations, hydraulic surveys, and environmental sewage monitoring. They are used to measure the time-averaged flow velocity at predetermined points in a cross-section. When paired with the CBL-1 type pump station current meter rod, they can measure the single-unit flow rate of small and medium-sized pump stations. They can also be used in conjunction with time-integrated suspended load samplers to measure flow velocity for calculating sediment transport rate.

2. Product Models

This series of instruments is designed for installation on a rod with a diameter of Φ16mm. Based on the structure of the signal reduction transmission part, they are categorized as follows:

LJ12-1A type — Signal output per revolution: 20 revolutions;

LJ12-1C type — Signal output per revolution: 1 revolution;

The two models have basically the same structure; only the A-type is described here.

3. Technical Parameters

(1) Propeller structure: Helical surface three-blade, left-hand rotation, PC engineering plastic

(2) Propeller rotation diameter D: 70mm

(3) Propeller hydraulic pitch b: 120mm

(4) Starting rotation speed V0: ≤0.06m/s

(5) Flow velocity measurement range V: 0.07～7m/s (experimentally calibrated Vmax=12m/s)

(6) Signal component structure: Magnetic reed switch electronic switch

(7) Calibration curve error: When V≥0.2m/s, the overall mean square error M≤±1.5%;

When V<0.2m/s, the average relative error E≤±5%

(8) Switch contact capacity: Current ≤50mA, Voltage ≤6V

(9) Reed switch operational cycles: 7 million times

(10) Continuous operation time: 2 hours (when sediment concentration ≤10kg/m3, water depth ≤10m, flow velocity ≤5m/s)

(11) Installation rod specification: CG16-1 type, Φ16mm×1.6m (can be divided into 2 sections)

(12) Operational water flow conditions:

Water depth range: When using the rod, the lower limit is 0.1m, and the upper limit depends on the rod length

Water temperature: 0～40℃

Suspended sediment concentration: ≤50kg/m3