Submersible electromagnetic flowmeter

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Submersible electromagnetic flowmeter by the diving electromagnetic flow sensor and diving electroma…

Products overview:
ZW - LDE seriesSubmersible electromagnetic flowmeterIs advanced technology development, the development of the intelligent flowmeter, and the old analog or non intelligent electromagnetic flowmeter has a very big difference, especially in the measurement accuracy, reliability, stability, use function and service life, etc.Submersible electromagnetic is high precision, high reliability and long service life of flow meter, so in the design of product structure, material selection, process, production assembly and the factory testing of every link in the process of we are all very detailed standards, we also design a set of ideal home is current, applied to the production equipment of electromagnetic flowmeter and traffic flow calibration device, thus both in software and hardware can effectively guarantee high quality products for a long time.

Second, the working principle:
ZW - LDE seriesSubmersible electromagnetic flowmeter measurement principle is based on Faraday's law of electromagnetic induction electric liquid for cutting lines of magnetic force in magnetic field movement, the potential is induced in the conductor, the induced potential E as follows:
E = KBVD;Type: K -- -- -- -- -- instrument constants;
B -- -- -- -- -- magnetic induction intensity;
V -- -- -- -- -- measurement of average flow velocity in the piping section;
D -- -- -- -- -- measuring inner diameter of the pipe cross section;
Measuring flow, the electrical conductivity of liquid with velocity V.
Through the perpendicular to the flow direction of magnetic field, the flow of the liquid conductivity sense if a voltage is proportional to the average flow velocity, the induced voltage signal by two or more direct contact with the liquid electrode detection, and through the cable to the converter by intelligent processing, then the LCD display or converted into 4 ~ 20 ma 01 KHZ and standard signal output.

Applications:
ZW - LDE seriesSubmersible electromagnetic flowmeter is mainly used to measure volume flow of conducting liquid and slurry in the closed pipeline.Such as water, sewage, slurry, pulp, all kinds of acid, alkali, salt solution slurry, food and so on, the electromagnetic flowmeter is widely used in petrochemical, steel, metallurgy, water supply and drainage, irrigation, water treatment, environmental protection sewage total amount control, paper making, medicine, food and other industrial and agricultural sector of the production process flow measurement and control;Apply to the amount of conductive liquid measurement.

Four, the main features:
1, the amount of full digital processing, strong anti-interference ability, reliable measurement, high accuracy, the flow measurement range of up to 150:1;
2, low EMI switching power supply, it is suitable for the power supply voltage variation range is big, EMI resistance performance is good;
3, USES the 16-bit embedded microcontroller processor, a fast calculation speed, high precision, programmable frequency low-frequency rectangular wave excitation, improve the stability of the flow measurement, low power consumption.
4, the SMD components and surface mount technology (SMT), circuit of high reliability;
Have no moving parts, 5, and the pipe unimpeded flow components, almost no additional pressure loss in the measurement;
6, in the field can be on-line modification range according to user's actual needs;
7, measurement results and the velocity distribution, the fluid pressure, temperature, density, viscosity and other physical parameters has nothing to do;
8, high-definition backlit LCD display, full Chinese menu operation, easy to use, simple operation, easy to understand;
9, with RS485 and RS232, Hart and Modbus digital communication signal output.(optional).
10, with functions of self-check and since the argument;
11, total hours recording function, total hours for the unit to record the flow rate, is suitable for the time-sharing measurement system (optional);
12, inside has three integrator can reverse the cumulative amount respectively show positive cumulative integrating quantity and difference, it has not always, can record 16 times time when power supply drop.(optional).
13, infrared carrying manipulator, 115 KHZ communication rate, long distance non-contact operation converter all function (optional).
Five, the technical parameters:
1, precision instrument: pipeline magnitude 0.5, 1.0;Plug in 2.5 on the Richter scale;
2, measuring medium: conductivity is greater than 5 mu S/cm of various liquid and liquid-solid two phase flow;
3, velocity range: 0.2 ~ 8 m/s;
4, work pressure: 1.6 MPa;
5, environmental temperature: - 40 ℃ ~ + 50 ℃;
6, medium temperature: ptfe lining 180 ℃ or less;Rubber lining 65 ℃ or less;
7, explosion-proof marks: Exmibd Ⅱ BT4;
8 and outside magnetic interference: 400 a/m or less;
9, shell protection: integration type: IP65;
10, points out: sensor IP68 (5 meters underwater, rubber lining only);Converter IP65;
11, the output signal: 4 ~ 20 ma DC, 0 ~ 750 Ω load resistance;
12, communication output: RS485 or CAN bus;
13, electrical connections: M20 x 1.5 internal thread, phi 10 cable hole;
14, power supply voltage: 90 ~ 220 v AC, 24 V.D C + / - 10%;
15, power consumption: 10 or less va.
Six, the structure form:
1, the sensor:
Sensor is mainly composed of measuring tube and electrode, excitation coils, iron core, magnetic yoke and shell. 
A, measuring catheter: by stainless steel tube, the lining and the connecting flange, as the carrier of measured liquid measurement working conditions on site. 
B, measuring electrode: installed in the measuring tube inside wall, and the axial direction perpendicular to a pair of electrodes to measure liquid signal generation. 
: c, excitation coil in a magnetic field measurement of intraductal two excitation coil. 
D, iron core and magnetic yoke: the excitation coil of the magnetic field generated import liquid, and the magnetic circuit. 
E, shell: instrument packaging. 
2, converter that is smart the secondary table, it will flow signal amplification processing, single chip microcomputer after the operation, can display flow, total amount, and can output pulse and analog current signal, used in the measurement or control of fluid flow.
3, product assembly form: it into a shape and size in two forms. 
A, a shape: mounted sensors and switches. 
B, size: separation installation sensor and converter, through the connecting cable form flow metering system. 
C, in order to adapt to the measurement demands of the different medium, the lining of sensor and electrode materials can have many choices.

Seven, according to excitation methods of classification:
To produce a uniform constant magnetic field, it needs to choose a suitable way of excitation.Such as divided according to the field current mode, have a dc field, ac (or other frequency) power frequency excitation, low-frequency rectangular wave excitation and dual-band rectangular wave excitation.
1, the dc excitation
Dc excitation method with direct current (dc) or use a magnet to produce a uniform magnetic field is constant.The dc excitation transmitter is affected by the ac electromagnetic interference is very small, so you can ignore the influence of the liquid in the self inductance.But using dc magnetic field is easy to make by measuring the electrolyte fluid of the pipe is polarized, the electrolyte by electrolysis in the electric field, produce positive and negative ions, in under the action of electric field force, ran to the anode, anion cation ran to the cathode, which will result in positive and negative electrodes were surrounded by ions of opposite polarity, seriously affect the normal work of the instrument.So, dc excitation only commonly used for measuring the liquid electrolyte, such as the liquid metal flow of mercury (room temperature and high temperature of liquid steel, lithium, potassium), etc.
2, ac excitation
Industrial use of electromagnetic flowmeter, most used (50 hz) power supply power frequency ac excitation method to produce alternating magnetic field, to avoid the dc excitation on the surface of the electrode polarization interference.But the use of ac excitation will bring a series of electromagnetic interference problem, such as orthogonal interference, in-phase interference, zero drift, etc.).Ac excitation is now replaced by low frequency square wave excitation.
3, low frequency square wave excitation
Low frequency square wave excitation waveform has two values (positive - negative) and three values (positive - zero - negative - zero) two kinds, the frequency of power frequency usually 1/2 ~ 1/32.Low frequency square wave excitation can avoid orthogonal electromagnetic interference of ac magnetic field, power frequency interference caused by distributed capacitance, inhibition of ac magnetic field within the tube wall and fluid caused by eddy current, dc excitation polarization phenomenon.

Eight, the straight pipe installation requirements:
Flowmeter sensor of straight pipe upstream and downstream of the installation points has certain requirements, otherwise it will affect the accuracy of measurement.
1, if the sensor installation point upstream of reducer, sensors upstream should be not less than 15 d straight pipe sections, such as the downstream straight pipe section should be not less than 5 d.
2, if the sensor is installed upstream of point have divergent tube, sensor should not be less than 18 d upstream straight pipe sections, such as the downstream straight pipe section should be not less than 5 d.
3, if the sensor installed upstream of point under the 90 ° elbow or sub, sensors upstream should be not less than 20 d straight pipe sections, such as the downstream straight pipe section should be not less than 5 d.
Upstream of four, if the sensor installed on the same plane has two 90 ° elbow, sensor should not be less than 25 d upstream straight pipe sections, such as the downstream straight pipe section should be not less than 5 d.
Upstream of 5, if the sensor installed in different plane has two 90 ° elbow, sensors upstream should be not less than 40 d straight pipe sections, such as the downstream straight pipe section should be not less than 5 d.
6, flow control valve or pressure regulating valve installed on the downstream side of the sensor 5 d as far as possible, if must be installed in the upstream of the sensor, the sensor should not be less than 50 d upstream straight pipe sections, such as the downstream straight pipe section should be not less than 5 d.
Pay special attention to
1, sensors installed upstream of point relatively close if equipped with valve, switch valve and affect the service life of the sensor is great, very easy to cause * sexual damage to the sensor.
2, sensors to avoid the overhead of very long pipe installed on the sensor, so that over time, as the drop sensor is very easy to cause between the sensor and the flange seal leakage, if necessary when installation, must be set separately in the upstream and downstream of sensor 2 d pipe clamp device.
Nine, installation considerations:
1, the sensor should be installed vertically, and fluid flows from bottom to top, in order to meet the solid and liquid two is in a state of mixed.The reason is that if there is solid in the medium (sand, gravel particles, etc.) are prone to precipitation.Have fish and weeds in another line of fish swimming in the pipeline, will cause the flowmeter output swing;Hang back and forth near the electrode weeds can also cause the output of the meter is not stable.Set at the entrance of upstream flow meter metal screen blocking fish and weeds into the measuring tube.
2, to prevent the negative pressure pipe set improper operation will cause negative pressure sensor inside.When closed, downstream of the valve in the flow meter at the same time, if the temperature is higher than the temperature of the fluid.Contraction after cooling, the pipe pressure is in danger of forming negative pressure.The negative pressure caused by the lining and metal vessel, cause leakage electrode.
3, near the flowmeter and negative pressure to prevent valve, open the valve on atmospheric pressure, in order to prevent to produce negative pressure in the sensor.Flowmeter downstream by a vertical line, if use flow upstream of the valve to close or adjust the flow sensor, the sensor will form a negative pressure measuring tube.In order to prevent negative pressure, need to add back pressure or use downstream to adjust and close the flow valve.
4, proper maintenance space, large diameter flowmeter are often installed in instrument well, for pipe installation, wiring, inspection and maintenance convenience, need to have the appropriate space.For observation, connection and maintenance convenience, instrument installation should have a certain height from ground, in order to facilitate cleaning, installation.

Ten, the main technical data:

1, the whole machine and the technology of sensor data:

2, converter technology data:

3, the choice of the lining:

4, import protection flange and the choice of grounding flange ring (or ground) :

5, the choice of electrode:

11, correct selection:

Instrument selection is very important work in instrumentation, relevant data show that the instrument in two-thirds of faults in the practical application is instrument error caused by selection or wrong installation, please pay special attention to.

1, collect data:

By measurement of body composition;
Large flow, small flow;
Z high work pressure;
, z z high temperature low temperature;

2, range scope confirmation:

General industrial use measured medium velocity of electromagnetic flowmeter with 2 ~ 4 m/s advisable, under special circumstances, z low velocity should not be less than 0.2 m/s, high z should be not more than 8 m/s.If the medium containing solid particles, commonly used flow rate should be less than 3 m/s, prevent excessive friction lining and electrode;For viscous flow, the velocity can choose more than 2 m/s, larger velocity help eliminate electrode automatic on the effect of viscous material, to improve accuracy of measurement.

Under the condition of the range of Q have been identified, according to the velocity V can be decided to the size of the flow meter diameter D, the range of the values calculated by the next type:

Q = PI D2V / 4
Q: flow (㎡ / h) D: pipe diameter V: velocity (m/h)

Electromagnetic flow meter range of Q zui flow value should be greater than expected, the flow of the normal value in a full scale slightly greater than the flowmeter calibration 50 is advisable.

3And the reference flow range:

4, selection of code:

Twelve, design selection and ordering information:

1, the measured medium: name, composition, status, electrical conductivity and electrical conductivity;

2, working temperature (℃);

3, work pressure (Mpa);

4, the pipe diameter (DN), the smallest, normal, scope of quantity (m3 / h);

5, corrosion resistance, wear resistance, whether there is a negative pressure;

6, installation requirements and the environment: a body or fission, signal output, communications, power supply;

7, installation environment: protection grade and explosion-proof requirements.

After-sales service commitment:

1, from the date of signing of the contract, I in the way provided for products of the company offers free maintenance and maintenance service, commitment to lifelong maintenance service;

2, jiangsu wei measurement and control instrument co., LTD. Sales manager will be in regular contact with customers, understand the usage of products, and solve the problems of the customers to use in the process of produce, free of charge to provide technical support;

3 the man-made damage is found, the warranty period, our company is responsible for the maintenance, and the resulting maintenance fee;

4, product quality problems or are not satisfied with product, the user can choose unconditional return, wei tt&c don't charge any fees, appear quality problem, bear the freight back and forth.