Doppler ultrasonic flowmeter

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The doppler ultrasonic flowmeter USES a non-contact clamping sensor to measure the liquid flow. The …

I. product overview
The host panel of the zw-ldn-1 series doppler ultrasonic flowmeter has a device that can adjust the transmitting power level on the spot, which can adapt to pipeline coating, stacking, corrosion and loose lining, etc., so as to ensure the instrument can work normally under these conditions. The host of the flowmeter has a unique digital filter design, which can connect the received signal waveform and automatically adjust to form an ideal waveform. Therefore, it can ensure the stability and reliability of the meter reading in the case of pipeline vibration or not too many straight pipe sections. Instrument installation and operation is very simple.

Ii. Working principle
Zw-ldn-1 series doppler ultrasonic flowmeters make use of the doppler effect in physics. The discontinuity in any flowing liquid will cause the reflected ultrasonic signal to produce frequency shift (that is, the signal produces phase difference). By measuring the phase difference, the velocity can be measured. Frequency shift is a linear function of flow rate, which can produce stable, repeatable and linear indication after being filtered by the circuit. In theory, these discontinuities could be suspended bubbles, solids, or interfaces caused by fluid disturbances. The sensor generates and receives ultrasonic signals, provides data to the host, which processes the signals and provides analog outputs for velocity display and volume flow display and accumulation, as well as relay output. In addition, the host contains a signal strength indicator that ensures satisfactory operation. Zw-200f is based on the principle of doppler ultrasound measurement, using phase difference method to process the signal. It has unique digital filtering technology and frequency modulation and demodulation technology, automatic shaping received waveform signal, it can measure the pipeline containing lining, and is not too sensitive to pipeline vibration.
The acoustic impedance of the reflected substance must be at least 10% different from that of the liquid (the difference in the velocity at which sound travels through the medium).
The particles in the liquid must be large enough (greater than 100um) or contain bubbles to cause longitudinal reflection of sound waves.
When installing a plug-in sensor, the upstream and downstream of the installation location must have a straight pipe segment of sufficient length. Usually, the upstream needs a straight pipe segment of 10D and the downstream needs a straight pipe segment of 5D. D is the pipe diameter.
Iii. Application:
Zw-ldn-1 series doppler ultrasonic flowmeters are mainly used for environmental inspection of urban sewage treatment plant and drainage pump station, and flow measurement of urban drainage, industrial wastewater, domestic sewage, mud, paper pulp and oil-water mixture in mining, oil field, metallurgy, chemical industry, oil refining, paper making, food and other industries. Suitable for steel, hard plastic pipe and other hard pipe, can be a variety of pipe diameter and wall thickness of the pipe containing suspended solid particles or bubbles of two-phase liquid measurement.
Iv. Main features:
1, can measure pure liquid and dirty liquid, so it is widely used in enterprises from tap water level medium to sewage, waste water, liquid containing slag measurement.
2. There is no strict requirement for the installation of straight pipe section, only 1 ~ 3D (pipe diameter) straight pipe section can obtain stable reading, which is not affected by pipe vibration and can be measured in the pump room.
3. There is no strict requirement for the condition of pipeline, so it can be measured for pipeline corrosion or lining cement material. 4, built-in large capacity rechargeable lithium battery, zui long continuous working time up to 20 hours.
5. The operation is very convenient. There are signal strength indicator, fluid status indicator, normal and fault indicator on the panel.
6. The instrument has a device (knob) that can adjust the transmitting power of the sensor, so that the instrument can work under a variety of harsh environments. Military-grade component design, main engine interior pavement brush with anti-corrosion, anti-mildew agent, main engine built-in desiccant, instrument normal life of more than 10 years.
V. technical parameters:
1. Tested media: slurry, sewage, grey water, beer, residue, soap liquid,
2, output method: 4 ~ 20 ma, the load is less than 600 Ω industrial water, raw water, the river (including air bubbles, solid);
3. Power supply voltage: AC200V (20%),50HZ. Body particle content > 20g/L) multiphase liquid;
4, ambient temperature: host: - 10 ℃ ~ + 45 ℃;
5. Pipeline material: metal, plexiglass, UPVC plastic, etc.;
6, probe: normal temperature - 20 ℃ ~ + 60 ℃ high temperature 20 ℃ ~ + 120 ℃;
7. Measuring pipe diameter: 10mm ~ 3000mm.
8. Environmental humidity: the relative humidity is less than 85%;
9. Medium flow rate: 0.04m ~ 10.0m/s;
10. Cable length: standard length: portable 5m;
11. Measurement accuracy: grade 2.0 (better than grade 1.5 after on-site calibration);
12. Operating environment: fixed and plug-in 10m
13. Installation: external mounting and plug-in installation;
14. Special length: 20m, 30m, 40m, 50m, 60m, 80.
15. Repeatability: 0.05%.
6. The distance between the host and the probe mounting point is determined as follows:
1. Display mode: 2 16LCD backlight display;
2. Instrument weight: (G) fixed type 4kg;
3, can display flow, flow rate, cumulative flow, etc.
(B) portable 4.5kg
1. Keyboard type: 4 4 touch keyboard;
2. External size: (G) stationary 275mm 203mm 118mm;
3, power off protection: power off automatic protection, automatic measurement;
(B) portable 340mm 210mm 235mm;
1. Cumulative output: optical isolation, emission and open collector output. Using the advanced principle of "doppler effect" measurement, the frequency difference between the reflected signal and the transmitted signal when the ultrasonic wave is reflected by a relative moving medium is used to obtain the liquid flow in the pipe.
2, the relationship is expressed as: Q is the liquid flow, K is the flow coefficient, A is the effective section of the pipeline, C is the Angle between the ultrasonic beam and the tube axis, f1 is the ultrasonic transmission frequency, and f is the frequency difference
3. The ultrasonic flowmeter adopts non-contact metering outside the pipe, and there is no contact between the measuring process and the liquid in the pipe, so it is not affected by the pressure, corrosion, pollution and other factors of the liquid.
Vii. Matters needing attention in application:
1. The basic rule of zui is to read the manufacturer's instructions carefully. The early problem with the ultrasonic flowmeter may have been (at least not ruled out) that the user did not understand the importance of certain basic steps, such as the correct installation of the transmitter on the pipe. In all cases, such as extreme changes in pipe temperature or irregular vibrations, the coupling of the pipe to sound waves and the relevant adjustment of the transmitter must be maintained.
2. When using the doppler and jet lag flowmeters to display the actual flow rate per unit volume, the fluid in the pipe under test must always be full. However, if both transmitters are located below the surface of the fluid in the pipe, the doppler flowmeter can also continuously show the flow rate of the fluid filling part of the pipe.
3. Most manufacturers indicate a small zui distance between the instrument and upstream and downstream valves, t-frames, pumps, and analogues. It is generally expressed as pipe diameter, usually 10~20 diameter upstream, 5 diameter downstream.
The function of the doppler flowmeter depends on the reflector in the flowing liquid. Therefore, in order to obtain reliable measurement data, attention must be paid to the lower limit of the concentration and size of solid particles or bubbles. In addition, the fluid must be fast enough to hold the material in suspension, and the manufacturer will provide typical velocity numerical specifications such as 6ft/s (1.8m/s) for solid and 2.5ft/s (0.75m/s) for small bubbles. In the past few years, several suppliers of doppler flow meters have introduced product models that work at frequencies above 1MHz. These products are required to work in a clear liquid because their reflections occur in the presence of swirls in the fluid. However, if there is a warning, it is intended to alert the user to limit the use of the technology for lower concentrations of bubbles and particles. Because during the operation of an ultrasonic flowmeter, the energy required for measurement is only partially through the measured liquid, Reynolds number (the ratio of inertial force to viscous force in the fluid) will affect the performance of the flowmeter. For example, when operating according to the above regulations, some doppler flow meters and jet lag flow meters require the number of zui Reynolds to be 4000 and 10000 respectively. It should be emphasized here that due to the above limitations, special attention should be paid to the guidance of the manufacturer's manual in this regard.

Typical success stories:
1, a petrochemical plant, the water pipe (700 mm) Φ lined with cement, pipeline internal and external surface corrosion is serious; Survey of water output of enterprises;
2. A petrochemical water purification plant: circulating water measurement and pump house sewage measurement;
3, a steel company: all kinds of circulating water, groundwater, pipeline complex; Monthly measurement of water consumption of each section of the enterprise;
4. Rubber factory of a petrochemical company: all kinds of circulating water and pump water.