Doppler flow meter.doc

1. Product and technical parameters

1.1 The principle of measuring flow velocity: The physical principle of Doppler frequency shift is used to measure the water flow velocity.

    What is the Doppler effect (Doppler frequency shift):

    The sound wave emitted by an ultrasonic wave is received and reflected by another receiver. If the sound source moves relative to the receiver, the frequency of the sound wave received by the receiver will be different from the frequency of the sound source.

    If the relative distance between two objects is reduced, the frequency of reception will increase.

If the relative distance between two objects increases, the received frequency decreases.

    Such Doppler effect often occurs in daily life. For example, when you hear the sound of an oncoming train whistle or the sirens of a police car (a sound source), the sound will appear to have a higher frequency; and When the train or police car is far away from you, the sound you hear will become lower.

Through the difference between the frequency of the transmitted ultrasonic wave and the frequency of the received ultrasonic wave, the specific flow rate can be calculated.

1.2 Product introduction

Ultrasonic Doppler flow meter is a device for measuring the flow rate of water in pipes, channels or rivers, and is mainly used in the following areas:

·Flood disaster monitoring

·Sewage Disposal

·Natural rivers

·Municipal water supply and drainage

·Water loss/infiltration monitoring

·Irrigation process monitoring

·Research on estuaries and tides

·Fishery/Water Conservancy

·Coastal erosion research

·Underdrain process monitoring

·Road drainage monitoring

·The canal process research

·River flow monitoring

Figure 1.2.1 Ultrasonic Doppler flow meter

A battery-powered system can be provided as needed to provide power in areas where power is inconvenient.

A GPRS wireless transmission kit can be provided as needed, so that the data detected on the scene can be viewed on the background server.

1.3 Technical parameters

Model: HFT-DPLLS

Structure: split type;

    Measurement types: flow rate, water depth, (water temperature measurement is an optional function)

    Purpose: online measurement

Flow velocity measurement range (water depth above sensor: 20cm):

    The positive flow velocity is +0.03m/s～+5.00m/s;

    The negative flow velocity is -1.00m/s～-0.03m/s (optional);

    Other flow rate ranges can be customized.

Deep range: 0.02～3m, 0.02～10m (please confirm the maximum water depth before ordering);

Flow velocity accuracy: ±1% (detection accuracy submitted by the Ministry of Water Resources);

Flow velocity accuracy: ±1～3% (measurement accuracy will change due to the influence of the on-site working environment);

Water depth measurement resolution: 1mm

Water depth measurement accuracy: 0.5%;

Temperature range: 0～60ºC; resolution: 0.1ºC;

Flow range: no flow measurement function

Working voltage: conventional 12～13VDC, the lowest working voltage is 10.3VDC, the highest is 14VDC.

Output signal: RS485 MODBUS protocol;

Wireless transmission (optional): GPRS type RTU wireless transmitter

Sensor supporting cable length: 10 meters;

Types of tested waterways: pipes, channels, natural streams, rivers;

Liquid pH requirement: PH value is between 6-8.

Liquid temperature requirement: 0～60℃, non-solidification

Liquid pressure requirement: 1 standard atmospheric pressure in natural environment

Tips: 1. The flow rate cannot be measured when the water is solidified or close to solidification.       

      2. The default maximum water depth cannot exceed 10 meters, if you want to exceed 10 meters, you need to clearly inform the manufacturer before ordering.

1.4 Measurement status and wiring

The data is calculated after 60 seconds after the power is turned on, and then the measurement data is calculated every 3 to 5 seconds. (The data here is not actively uploaded, but passively uploaded, and the measured data can be obtained only after the host computer sends a query command.)

The normal working power supply of the ultrasonic Doppler flow meter sensor is 12～13VDC, and the power supply current is 120mA.

Continuous maximum working power consumption: 14V×120ma=14V×0.12A=1.68W.

The cable is a four-core shielded wire, two wires for the power supply, and two wires for the 485 signal.

    The power cord is red positive, white is negative, blue is 485A, and yellow is 485B.

1.5 Product structure diagram

Figure 1.5.1 Product structure diagram

1.6 Product installation base 

Figure 1.6.1 The top view of the connection between the sensor and the mounting base

2. Product installation

2.1 Installation conditions and location in the channel

Measure on rivers and channels. For conventional ultrasonic Doppler flow meters, as long as the lowest water level exceeds 5 cm above the sensor, it can be measured. If the actual water level is relatively low, you can consult the manufacturer’s technicians to choose a low-level ultrasonic Doppler flow meter according to the actual situation.

The standard withstand voltage of the sensor for measuring the water level is 100Kpa, which is a water depth of 10 meters. If you need more pressure resistance, you need to specify before ordering. The maximum pressure resistance can be 1000KPa, which is 100 meters water depth.

Ultrasonic Doppler flow meter is suitable for water quality with solid content not more than 20kg/m³.

First, determine the lowest water level, which is 5 cm higher than the top of the sensor.

The sensor should be installed as close as possible to the bottom of the canal. If there are a lot of sediment, silt, water weeds or rocks at the bottom of the canal, the installation position can be raised to avoid being covered by sediments and water weeds or impacting the sensor by rocks.

The ultrasonic Doppler flowmeter should be installed in a place where the water flow is stable. The place where the water flow is not stable is turbulent in most cases. The measured flow velocity under turbulent flow conditions is pulsating, unstable, and the error will be large.

Applications:

      Mainly used in sewage plants, water plants, mines, water conservancy, power plants, chemical plants, steel plants, smart water projects, various monitoring projects of geological disasters, municipal projects, sponge city projects, urban inland river governance projects, hydrology, water conservancy informatization construction Projects and other industries, scientific and reasonable management system and sound quality control system, realize product traceability management, help product safe and efficient operation, won the China National Chemical Corporation, Harbin Institute of Technology, Baosteel Group, China State Construction Group, COFCO, The trust of representative users in the industry, such as Hengan Group, has accumulated rich experience in on-site disposal of instrument products in various fields.