KNF-1321Pro Dual-Mode Flow Meter – Radar & Ultrasonic Doppler for Full/Non-Full

Product Specification

1. Product Principle
The product integrates a radar flowmeter and an ultrasonic Doppler flowmeter, and simultaneously possesses two functions: radar non-contact flow measurement and ultrasonic Doppler contact flow measurement. The equipment is generally installed on the top of the pipeline. When the pipeline is not full, radar flow measurement (radar wave for measuring flow velocity and water level) is used; when the pipeline is full, ultrasonic Doppler flow measurement (ultrasonic Doppler for measuring flow velocity, pressure sensor for measuring water depth) is enabled, and the cross-sectional flow can be displayed.
The radar flow velocity sensor and radar water level sensor are located at the top of the equipment, while the ultrasonic Doppler flow velocity sensor and pressure sensor are located at the bottom of the equipment. There is a certain overlapping area between them. When the water level is shallow, the radar flow velocity and radar water level operate. When the water level gradually rises and covers the ultrasonic Doppler flow velocity sensor and pressure sensor, it switches to the Doppler flowmeter operation mode.
Both of them can calculate the cross-sectional flow based on the measured flow velocity and water level and the pre-input cross-sectional dimensions, using a certain water mechanics model.
Radar flow velocity measurement principle:
The radar flowmeter measures the speed of moving objects through microwaves. Its working theory is based on the Doppler principle, that is, when microwaves are irradiated onto a moving object, a frequency change proportional to the speed of the moving object will occur. The difference in frequency between S2 and S1 is the Doppler frequency shift Sd. Assuming the water flow velocity is V, the Doppler frequency shift Sd is proportional to the fluid flow velocity V. Through Sd, V can be calculated.

Ultrasonic flow velocity measurement: The measurement of flow velocity is achieved by the ultrasonic probe (transducer) emitting and receiving ultrasonic signals and performing corresponding calculations and processing: Transducer 1 emits an ultrasonic signal with a frequency of f1, which is emitted at a certain angle from underwater to the water surface. After encountering suspended particles or bubbles in the water, the frequency shifts and is reflected back to transducer 2 at a frequency of f2. This is the Doppler effect. The difference between f2 and f1 is the Doppler frequency shift fd. Assuming the flow velocity of the fluid is v, and the ultrasonic speed is c, the Doppler frequency shift fd is proportional to the flow velocity v. There are a large number of impurity particles and bubbles in water. Each reflected particle corresponds to a Doppler frequency shift fd. By conversion, the flow velocity of these numerous particles can be obtained, and this average flow velocity of the large number of particles is also the average flow velocity of the fluid.

2. Features and Applications
1) Both full pipe and non-full pipe can be measured, with automatic switching;
2) Dual-mode measurement using ultrasonic and radar technology;
3) Installed at the top of the pipeline, effectively reducing the impact of accumulated debris;
4) Built-in dual water level and dual flow rate measurement design, providing full coverage to ensure no measurement blind spots;
5) Supports 485 sensor data collection, with a long communication distance;
6) Protection level IP68, suitable for various measurement environments;
7) Embedded pipe network flow calculation model, directly outputting monitoring data such as water level, flow rate, and flow volume;
8) Compact in size, compact design, quick and easy installation, no need to go down the well for maintenance, and easy disassembly.

    At present, the urban drainage network still has problems such as mixed connection of rainwater and sewage pipes, blockage and clogging, as well as illegal discharges and leakage.
The new generation of drainage network flow meters adopt two measurement methods: contact and non-contact. When the network is not full, the radar non-contact measurement method is used, which can effectively reduce the impact of sludge, oil, and floating substances in the sewage on the sensor coverage, greatly reducing the construction and maintenance costs; when the network is operating at full capacity, the equipment is immersed in water and the ultrasonic contact measurement method is used to measure the flow velocity information, ensuring the full-process monitoring of the flow in different states of the network.

3.Technical Specifications

Ultrasonic Doppler Velocity Sensor

• Transmission Frequency: 1 MHz
• Range: 0.02 m/s ～ 10 m/s
• Accuracy: 1% of measured velocity ± 0.01 m/s
• Resolution: 1 mm/s

Radar Velocity Sensor

• Transmission Frequency: 24 GHz
• Antenna Beam Angle: 12° × 24°
• Range: 0.03 m/s ～ 20 m/s (Depends on flow conditions)
• Accuracy: 1% of measured velocity ± 0.01 m/s
• Resolution: 1 mm/s

Pressure Water Level Sensor

• Range: 0 ～ 10 m (Customizable range available)
• Resolution: 1 mm
• Accuracy: ±0.5% FS (Full Scale)

Radar Water Level Sensor

• Transmission Frequency: 120 GHz
• Antenna Beam Angle: 6° × 6°
• Range: 0.03 ～ 10 m
• Resolution: 1 mm
• Accuracy: ±2 mm

General Technical Specifications

• Voltage: 9-24V
• Power Consumption (Measuring): ≤ 120mA
• Parameter Settings: Configurable via Bluetooth Mini Program (Operation accessible from ground level).
• Mode Switching: Automatically switches to flow measurement mode based on water level.
• Operating Temperature: -30℃ ～ 70℃
• Battery Life (Optional): ≥ 1 year
• Housing Material: Engineering Plastic
• Ingress Protection: IP68
• Communication Protocol: MODBUS-RTU
• Reliability (MTBF): ≥ 25,000 hours
• Dimensions: 260 (L) × 122 (W) × 112 (H) mm