Agricultural Irrication Magnetic Flow Meter-PMF-A

AGRICULTURAL IRRICATION MAGNETIC FLOW METER

PMF-A series electromagnetic flow meter for agricultural irrigation

Suitable for conductive media with conductivity greater than 5μS/cm, wide nominal diameter range, suitable for various actual environmental conditions, with multiple power supply modes and multiple signal outputs, adopting standard RS-485 serial communication interface, supporting international standard MODBUS-RTU communication protocol wired communication networking mode, and having cumulative pulse equivalent output.

FUNTION

n  Excellent repeatability and linearity ofmeasurement

n  Good reliability and anti-interference performance

n  Good pressure and tightness

n  Measuring tube with low pressure loss

n  High intelligence

n  Maintenance-free

Industry application

Agricultural irrigation magnetic flow meter is a flow meter product developed by our company aiming at the current situation of agricultural irrigation and specially for the statistics of irrigation water. There are a large number of agricultural irrigation wells in China. If the existing flow meters are used, the investment is huge and the maintenance cost is high. This product has the advantages of low cost, simple installation and debugging, easy operation, no restriction of on-site environmental factors, saving equipment investment, and convenient later maintenance. It is a flow meter with high cost performance and has a broad application prospect in agricultural irrigation.

Product overview

Agricultural irrigation magnetic flow meter consists of a sensor and a converter. The sensor consists of a measuring tube, an electrode, an excitation coil, an iron core and a shell. After amplifying, processing and calculating the flow signal, the converter can display instantaneous flow, cumulative flow, output pulse, analog current and other signals for measuring and controlling fluid flow. PMF-A series electromagnetic flow meter adopts intelligent converter, which not only has the functions of measurement and display, but also supports the functions of data remote transmission, wireless remote control and alarm.

Working principle

The working principle of Agricultural irrigation magnetic flow meter is based on Faraday's law of electromagnetic induction. In the right figure, two electromagnetic coils at the upper and lower ends generate a constant or alternating magnetic field. When the conductive medium flows through the electromagnetic flow meter,the induced electromotive force can be detected between the left and right electrodes on the wall of the flow meter. The induced electromotive force is proportional to the flow rate of the conductive medium, the magnetic induction intensity of the magnetic field and the conductor width (the inner diameter of the flow meter measuring tube), and then the medium flow can be obtained by calculation.

The process parameter equation of induced electromotive force is:

E = K B V D,

Remarks:

E—induced electromotive force; D—measure the inner diameter of the pipe; B—magnetic induction intensity; V— average flow velocity;

K—coefficient related to magnetic field distribution and axial length;

Ordering instructions:

The following problems should be clarified when selecting electromagnetic flow meter:

(1) The medium to be measured must be conductive fluid, and it cannot be measured for non-conductive media such as gas, oil products and organic solvents.

(2) When selecting models and specifications when ordering, the manufacturer shall be provided with the measuring range of electromagnetic flow meter, and the manufacturer shall calibrate within this measuring range to ensure the measuring accuracy of the instrument.

(3) The user shall provide the manufacturer with the parameters in the selection table of the measured medium, process parameters, flow rate, working temperature and pressure, etc., and select the appropriate ones according to these parameters flow meter.

(4) When purchasing the split electromagnetic flow meter, the user shall ask the manufacturer for the length of wiring according to the distance between the installation position of the converter and the sensor.

(5) If users need to install accessories, such as matching flanges, metal ring gaskets, bolts, nuts, washers and other additional requirements, they can put forward when ordering.

Selection description

Instrument selection is a very important work in instrument application. Relevant data shows that two-thirds of faults in practical application are caused by wrong instrument selection or wrong installation. Please pay special attention.

Detailed description of the selection table

Pressure grade 

l Pressure grade refers to the rated pressure grade that the sensor can bear. Generally, the pressure on the sensor is determined by the pressure exerted by equipment (such as pump, etc.) on the medium in the pipeline with the measured flow. If the pressure exceeds the rated pressure of the sensor, it will cause the electromagnetic flow meter to leak water, fail to work normally and even damage the electromagnetic flow meter.

l The pressure grade is 1.6MPa, and a certain margin should be reserved during measurement. For example, if the working pressure of pipeline medium is 0.8MPa, the electromagnetic flow meter pressure level of at least 1.6MPa should be selected.

Installation form

l Clamping installation shall be matched with the pipe installation mode of the measured flow. Clamping installation requires fixing the sensor between the flange interfaces on both sides of the measured flow pipeline.

l There are stainless steel pipes, cast iron pipes, PE pipes, etc. which can be installed with electromagnetic flow meter. Different pipes are installed in clamping mode. Pay attention to both sides of the sensor during installation Rubber gaskets of corresponding specifications should be added to prevent fluid dripping.

BORE

l Generally, the caliber of electromagnetic flow meter should match the caliber of the measured flow pipeline, and the caliber should also match the flow rate of the measured medium. See the caliber selection table, and try to make the common flow of the measured medium in the yellow font area of the table.

Flow meter structure量计结构

Integrated

l  Under the condition that the field environment is good, the integrated type is generally selected,that is, the sensor and the converter are integrated

l  Sensor and intelligent converter assembly, price and installation costs are more economical, intuitive display.

l  prevent electronic components of smart converters from being affected by fluid temperature in pipes

l  Avoid direct installation outside or in a harsh environment.

l  Integrated default protection level IP65

Split type

Use split type when using.

l  Ambient temperature or converter surface temperature greater than 55 ℃.

l  Where the pipe vibrates more

l  Will seriously corrode the shell of the converter.

l  Field humidity or corrosive gas occasions.

l  Flow meter installed in high altitude or underground and other inconvenient debugging occasions

l  IP68. for split default protection A split electromagnetic flow meter with IP65 protection grade can be selected without immersion in water or other special conditions,which should be specially proposed when ordering.

OUTPUT SIGNAL

PMF-A series of electromagnetic flow meter output signal has 4-20mA,RS-485、 frequency / pulse three types. The user needs to select the output signal according to the actual situation and the equipment.

Working power supply

PMF-A series of electromagnetic flow meters have AC 110/220 V(100-240 V), DC 24 V.

Grounding ring option

l  The grounding ring is used to ground the measured medium and improve the measurement stability of the electromagnetic flow meter. However, the grounding ring needs to be in contact with the measured medium, which is likely to be corroded and worn, and usually needs to be replaced after being used for a period of time.

l  PMF-A series electromagnetic flow meters generally use grounding electrodes instead of grounding rings, which can achieve better grounding effect and increase the convenience and reliability of use.

l  When installing the grounding ring, the grounding ring needs to be installed at an accurate pipeline position to avoid affecting the flow field of the measured medium

The protection grades

According to national standard GB 4208-48 or IEC standard of international electrotechnical commission (IEC 529-76), the protection level of the enclosure is as follows.

SIZE

Integrated

Parting type

Note: The size and weight of the electromagnetic flowmeter marked here may be different from the real product, and the real product shall prevail.