Wide applications for magnetic flow meters
With the rapid development of world’s industry, the electrical measurement instrument engineering industry has gradually played an increasingly important role in my country's industrial production. Among them, electromagnetic flowmeters are more and more widely used,2”mag flow meters are the common request magnetic flow sensor size. The process parameters in many enterprises rely more and more on magnetic flowmeters. Magnetic flowmeters are widely used in many fields. Large size magnetic flow meters , such as 6", 8 inch ,10 inch,12 inch electromagnetic flow meter, 14" magnetic flow meters are mostly used in water supply and drainage projects; medium and small diameters magmeters( such as 4 inch, DN100,3” eletromagentic flow meters, are often used for high requirements or difficult to measure occasions, such as blast furnace tuyere cooling water control in iron and steel industry, measurement of pulp and black liquor in paper industry, strong corrosive liquid in chemical industry, ore pulp in non-ferrous metallurgical industry; small magnetic meters ,for example 2 inch mag flow meter,50mm dia size mag flow meters, 1", 1/2 inch, 3/4”.,etc are often used in pharmaceutical industry, food industry, biological Chemical and other places with hygiene requirements. The article specifically introduces the basic requirements for 3” electromagnetic flowmeter selection, installation and commissioning of 2” magmeter, and elaborates on the problems and countermeasures that are easy to occur in the installation and commissioning of electrical instruments.
Working principle of magnetic flow meters
Electromagnetic flowmeters are flowmeters that measure flow according to Faraday's law of electromagnetic induction. The advantages of electromagnetic flowmeters are that the pressure loss is extremely small and the measurable flow range is large. The ratio of the maximum flow rate to the minimum flow rate is generally more than 20:1. It is suitable for a wide range of industrial pipe diameters. The output signal and the measured flow rate are linear, and the accuracy is high. The measurable conductivity is greater than or equals to 5us/cm the fluid flow of acid, alkali salt solution, water, sewage, corrosive liquid and mud, pulp, paper pulp, etc. 2” magmeter cannot measure the flow of gas, steam and pure water.
When the conductor moves in the magnetic field to cut the magnetic field lines, an induced potential will be generated in the conductor, and the magnitude of the induced potential is proportional to the effective length of the conductor in the magnetic field and the speed of the conductor in the magnetic field perpendicular to the direction of the magnetic field. In the same way, when the conductive fluid flows in the vertical direction in the magnetic field and cuts the magnetic induction line, an induced potential will also be generated on the electrodes on both sides of the pipe. The direction of the induced potential is determined by the right-hand rule, and the magnitude of the induced potential is determined by the formula EX=BDV(1).
In the formula,
EX is the induced potential;
B is the magnetic induction intensity,
D is the inner diameter of the pipe,
and v is the average flow velocity of the liquid.
However, the volume flow qv is equal to the product of the flow velocity V of the fluid and the cross-sectional area of the pipe (IID')/4. ) to replace the formula: QV=(IID/4B) *EX.
It can be seen from the formula that when the pipe diameter D is fixed and the magnetic induction intensity B is kept constant, the measured volume flow has a linear relationship with the induced potential. If root electrodes are inserted on both sides of the pipeline, the induced potential Ex can be induced, and the volume flow can be obtained by measuring the magnitude of this potential. If the density of the measured medium is known, the mass flow rate can also be obtained.
How to buy 2” mag flow meter?
(1) The diameter and flow range of the process pipe determine the diameter of the flowmeter and whether it is necessary to use a reducer, 2” mag flow meter flow range is 13-264 gpm, or 50-1000 LPM,3-60 m3/h, please using our SHD 2 inch electromagnetic flow meter within this range.
(2) Elements of environmental conditions of use: protection level, explosion-proof requirements, power supply voltage, process pipeline material (metal and insulated pipelines) - determine the requirements for grounding rings of 2” mag flow meter.
(3) The physical and chemical properties of the measured medium: electrical conductivity, temperature, pressure, air bubbles, solid particle composition, and corrosiveness - determine the electrode material, type, lining material of 2 inch or DN50 mm magnetic flow sensor material.
(4) Requirements for the structure of DN50 magnetic flow meter : integral display or remote display magnetic flow converter, and remote digital indicator magnetic flow meter should provide cable length requirements requirements, Silver Automation Instruments offers standard 10 mts cable , users can also such as 20 meters, 30meters cable distance for remote reading.
(5) 2” mag flow meter accuracy: 0.5% of reading
(6) 2” magnetic flow transmitters output signal, display content, communication interface and self-diagnosis function - determine the converter model, 2 mag flow meter digital type magnetic flow meters offers 4-20mA current output ,frequency output, pulse output, MODBUS RS485 ,HART or ProfibuS-DP Protocols.
(7) Suitable type magnetic flow meter
Selection principle: to ensure that the working conditions of the measurement site are met; to meet the accuracy and functional requirements of the instrument; to strive for cheap and moderate prices 2” magnetic flow meter;
(8) Material selection of DN50 Electromagnetic Flowmeter
Electrode Material for 2” mag meter flow measuring tube:
Stainless steel SS316L electrodes magnetic flow meter is mainly used for domestic industrial water, well water, raw water, sewage flow meter, drinking water flow meter, dilute acid, dilute alkali and other weakly corrosive acids, alkalis and salts.
Titanium material electrodes flow meter can be used as seawater flow meters, various chlorides and hypochlorites flow metering device, caustic soda (NaOH) flow meters
Tantalum electrodes used in 2” magnetic flow meter sensor can archive excellent corrosion resistance, very similar to glass, can be made for 85% ,98% sulfuric acid flow meter,HCL flow meter, nitric acid flow meter, Aluminum sulfate flow meter, sulphate solution flow meter,
Platinum-iridium: comparable corrosion resistance, can be used very highly corrosive liquid flow measurement; such as sulfuric acid flow measurement running at high temperature;
Low noise electrode: optional Hastelloy material or SS316 material, suitable for slurry and fiber media.
(9) Selection of electromagnetic flowmeter liner
It should be selected according to the corrosiveness, abrasiveness and temperature of the measured medium.
Hard rubber and neoprene rubber are resistant to general weak acid and alkali corrosion, and temperature resistance is 80 °C.
Neoprene rubber has wear resistance.
PTFE is almost resistant to strong acid and alkali corrosion except hot phosphoric acid. The medium temperature can reach 180 ℃, but not resistant to wear.
Polyurethane rubber has good abrasion resistance, but it is not resistant to acid and alkali corrosion. The temperature resistance is also poor, and the medium temperature is less than 65 °C.
Most of the temperature at our site is high, so most of the linings made of Teflon for 2” magnetic flow meters.
Mag flow meter installation
(1) The direction of the arrow on the 2” mag flow sensor must be consistent with the actual flow direction (if installed in reverse, the flow direction item in the converter menu must be corrected). 2” magnetic flow meter bidirectional liquid measurement is possible.
(2) The installation must ensure that the pipeline is full of liquid during measurement.
(3) The straight pipe section before DN50 mag meter is upstream 5DN and the downstream 2DN.
(4) Mag flow sensor and flow converter must be well grounded.
Grounding requirements: The electromagnetic flowmeter transmitter shell, shielded wire, measuring conduit and pipes at both ends of the transmitter must be grounded and the grounding points should be set up separately, and must not be connected to the public ground wire such as motor and electrical or the water and sewage pipes; the converter part has passed The cable is grounded, and there is no need to ground it again, so as to avoid interference caused by different potentials.
Grounding ring: If the process pipeline is an insulating material, a grounding ring must be used to stabilize the boundary conditions to improve the measurement quality and accuracy. In addition, some electromagnetic flowmeters have built-in grounding, we normal offer 3 pairs electrodes magnetic flow meters, 2 for measurement purpose and the rest for grounding purpose.
