Small diameter electromagnetic flowmeter

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Small diameter electromagnetic flowmeter show the scene of the meet at the same time, also can outpu…

Products overview:
ZW - LDE seriesSmall diameter electromagneticFlow meterVolume tube has no moving parts and components resistance, no pressure loss, won't produce congestion measurement, reliable and strong anti-jamming capability of small volume, light weight, easy installation, less maintenance, wide range measurement is not affected by the fluid temperature, density, pressure, viscosity and conductivity changes to him on the influence of opening reform installation, installation is simple, small quantities more general electromagnetic flowmeter cost and installation cost is low, especially suitable for small diameter pipeline flow measuring the use of advanced processing technology, solid-state encapsulation, long service life, the instrument has good measuring precision and stability.

Second, the working principle:
ZW - LDE seriesSmall diameter electromagnetic flowmeter is based on Faraday electromagnetic induction principle, with the sounding pipe axis and the magnetic field lines in the vertical tube wall installed on a pair of detecting electrodes, when conducting liquid along the measuring tube axis movement, conductive liquid cutting lines of magnetic force induced electric potential, the induction electric potential by two detection electrodes detection, numerical size and flow into a direct ratio, its value is: E = KBVD type:
E - induction electric potential;
K - factor related to the magnetic field distribution and the axial length;
B - magnetic induction intensity;
V - conductive liquid average flow velocity;
D - electrode gap;(the measuring tube diameter)
Sensor will be induced potential E as traffic signal, sent to the converter, amplifying, transform filter with a series of digital processing, USES dot matrix LCD display with backlight instantaneous flow and cumulative flow.Converter has 4 ~ 20 ma output, alarm output and frequency output, and is equipped with RS485 communication interface, and supports HART and MODBUS protocol.
Applications:
ZW - LDE seriesSmall diameter electromagnetic flowmeter has a wide range of USES, the application in the chemical industry, environmental protection, textile, metallurgy, mining, pharmaceutical, paper making, water, food, sugar, brewing and other industries in the process piping conductive medium of liquid flow metering;In addition to measuring general conductive liquid, according to user's special needs, can also be measured conductive liquid solid two phase flow, high viscosity liquids and salts, such as strong acid, strong alkali liquid flow.
Four, the structure of the flow meter:
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, the converter:
Is the smart secondary table, it will flow signal amplification processing, microcontroller after 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.

Five, the main features:
1, instrument structure is simple, reliable, have no moving parts, long working life.
2, no closure choke parts, there is no pressure loss and flow blocking phenomenon.
3, no mechanical inertia, fast response and good stability, can be applied to automatic testing, adjusting and SPC system.
4, the measurement precision is not affected by the type of measured medium and its temperature, viscosity, density, the influence of physical parameters such as pressure.
5, adopt ptfe or rubber lining material and Hc, Hb, 316 l, the different combination of electrode materials such as Ti can adapt to the needs of different medium.
6, with pipeline, plug-in, such as a variety of flow meter type.
7 block, using EEPROM memory, measuring operational data storage safe and reliable protection.
8, integration and separation of two kinds of model.
9, high-definition LCD backlit display.
Six, the technical parameters:
1, precision instrument: pipeline magnitude 0.5, 1.0;Plug in 2.5 on the Richter scale are unlikely.
2, measuring medium: conductivity is greater than 5 mu S/cm of various liquid and liquid-solid two-phase fluid.
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 material 65 ℃ or less.
7, explosion-proof marks: Exmibd Ⅱ BT4.
8, explosion-proof number: GYB01349.
9, outside magnetic interference: 400 a/m or less.
10, shell protection: integration type: IP65;
In mold: sensor IP68 (5 meters underwater, rubber lining only);Converter IP65.
11, the output signal: 4 ~ 20 ma DC, load resistance Ω 0 ~ 750.
12, communication output: RS485 and CAN bus.
13, electrical connections: M20 x 1.5 internal thread, phi 10 cable hole.
14, power supply voltage: 90 ~ 220 v AC, 24 + / - 10% V.D C.
15, zui big power consumption: 10 or less va.

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, installation requirements:
The choice of installation environment
1, should as far as possible away from strong electromagnetic field equipment.Such as big motor, transformer, etc.
2, the installation place should not have a strong vibration, environmental temperature change is not big.
3, easy to install and maintenance.
The choice of the installation position
1, sensors, flow mark on the direction of the measured medium flow and the pipe must be consistent.
2, installation location must ensure that the measuring tube in the book is full of measured medium.
3, and the choice of fluid flow pulse smaller places, which should be far away from the pump and local resistance (valve, elbow, etc.)
4, the measurement of two-phase fluid, should choose is not easy to cause the location of the phase separation.
A negative pressure, avoid installed in a tube of five places.
6, when makes the electrode measured medium, measure the tube inner surface adhesion, scaling, suggest the measuring tube flow velocity of no less than 2 m/s.
At this time can use reducing pipe diameter slightly smaller than the process.For uninterrupted flow in the process piping cleaning electrode and the measuring tube, sensor can be used parallel installations, and cleaning.
The choice of the installation site
In order to make the transmitter work stability, when choosing the location should be paid attention to the following requirements:
1, try to avoid strong ferromagnetic objects and concrete equipment of electromagnetic field (such as a big motor, transformer, etc.), so as to avoid the magnetic field of magnetic field effect sensor and traffic information.
2, should be installed in a dry and ventilated place, should not be in damp, easy seeper place of installation.
3, should try to avoid weathered, avoid environmental temperature is higher than 45 ℃ and relative humidity is more than 95.9%.
4, choose to facilitate maintenance and convenient place.
5, flow meter should be installed in the pump back end, never on the suction side of the installation;Valve should be installed in the downstream flow meters.

Nine, installation considerations:
1, when moving and lifting sensor, should will sling set beside the sensor on both ends of the flange neck position, do not in the measurement, hoisting so as not to damage the lining tube inserted into the pipe to help.
2, before the installation, the sensor electrode with alcohol cotton in carefully erased due to causes such as hand touch the surface of the electrode material grease stain.
3, the inner diameter of the sealing washer when installation should be consistent with the sounding pipe lining inside.
4, must ensure that the terminal box is dry, otherwise the instrument measurement error may result.
The preparing work before ten, run:
1, put into operation after installation wiring should be checked again before the installation, wiring is correct.(the size)
2, before the bed bottom valve is opened, the sensor after the valve closed, let the sensor with the medium.
3, after the completion of the preparation, upstream of the valve to open the first sensor, then slowly open the downstream of the valve, observe the converter instantaneous flow display should be toward the direction of change, that signal lines in the right direction.Otherwise, will signal A and B connection swap position.(the size)
4, open the sensor before and after the valve, drainage for a few minutes, the gas discharge tube.
5, close the sensor downstream of the valve, then close upstream of the valve, the measured medium is inside the sensor.And then to form a complete set of adjustment.Sensor and converter matching coefficient of zero adjustment and instrument set converter specifications, please read them.

11, 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:

Twelve, 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:

13, 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.