Electromagnetic flowmeter
Electromagnetic flowmeter is a kind of measurement according to the law of farad electromagnetic ind…
Description：
An overview,
Electromagnetic flowmeter is a kind of measurement according to the law of farad electromagnetic induction tube conducting medium volume flow sensing instrument, MCU embedded technology, digital excitation, at the same time in the electromagnetic flow meter adopting CAN field bus, at first, the technology to meet the domestic leading level.Electromagnetic flow meter according to the scene of the meet at the same time, also can output 4 ~ 20 ma current signal for records, adjust and control, has been widely used in chemical industry, environmental protection, metallurgy, medicine, paper making, water supply and drainage and other industrial technology and management.Electromagnetic flowmeter in addition to the general conductive liquid flow can be measured, can also be measured liquid-solid two phase flow, high viscosity fluid and salt, strong acid, strong alkali liquid volume flow.
Second, the characteristics of
Low instrument structure is simple, reliable, and have no moving parts, long working life.
No closure choke parts, there is no pressure loss and flow blocking phenomenon.
No mechanical inertia, rapid response, good stability and can be applied to automatic testing, adjusting and SPC system.
Low measurement precision is not affected by the type of measured medium and its temperature, viscosity, density, pressure and other physical parameters.
Use teflon or rubber lining with HC, HB, 316 l, the different combination of electrode materials such as Ti can adapt to the needs of different medium.
Low with pipeline, plug-in, such as a variety of flow meter type.
No closure choke parts, there is no pressure loss and flow blocking phenomenon.
No mechanical inertia, rapid response, good stability and can be applied to automatic testing, adjusting and SPC system.
Low measurement precision is not affected by the type of measured medium and its temperature, viscosity, density, pressure and other physical parameters.
Use teflon or rubber lining with HC, HB, 316 l, the different combination of electrode materials such as Ti can adapt to the needs of different medium.
Low with pipeline, plug-in, such as a variety of flow meter type.
Low block using EEPROM memory, measuring operational data storage safe and reliable protection.
Low type with integration and separation of two forms.
Low high-definition LCD backlit display.
Low type with integration and separation of two forms.
Low high-definition LCD backlit display.
Three, technical parameters
| Suitable diameter | DN15mm－2600mm | |
| Electrode materials | 316 l (stainless steel), HC hartz (C), HB (hartz B), Ti (Ti), Ta (Ta) | |
| Applicable medium | Liquid conductivity > 5 us/cm | |
| Measuring range | 0.1 ~ 10 m/s (can be extended to 15 m/s) | |
| Maximum range | 0.5 ~ 10 m/s, recommend 1 ~ 5 m/s | |
| Precision grade | 0.3, 0.5, 1.0 (with diameter distinguish) | |
| The output signal | 4 ~ 20 madc, load 750 Ω or less;0 ~ 3 KHZ, 5 v active, variable pulse width, high effective frequency output: RS485 interface | |
| Pressure of work | 1.0 MPa, 1.6 MPa, 1.0 MPa, 16 MPa (special) | |
| The fluid temperature | - 20 ℃ ~ 80 ℃, 80 ℃ ~ 130 ℃, 130 ℃ ~ 180 ℃ reference lining material | |
| The environment temperature | Sensors - 40 ℃ ~ 80 ℃;Converter to 15 ℃ to 50 ℃ | |
| The environment temperature | 85% RH or less (20 ℃) | |
| Cable outlet size | M20×1.5 | |
| Power supply | 220VAC±10%;50Hz±1Hz;24VDC±10% | |
| Power consumption | ≤8Ｗ | |
| Enclosure protection class | One-piece: IP65 split type: sensor IP6 IP68 converter | |
| Grounding ring material | 1 cr18ni9ti (stainless steel), HC hartz (C), Ti (Ti), Ta (tantalum), Cu (copper) | |
| Connecting flange | Gb GB9119-88 (DIN2051 BS4504) http://www.zgyb18.com/index.html | |
Four, principle of work
The electromagnetic flowmeter measurement principle is based on Faraday's law of electromagnetic induction instrument automation.Flowmeter measurement tube is a lining insulation not short magnetic alloy pipe.Two electrodes along diameter direction through wall is fixed on the measuring tube.The electrode head and basic flush lining the inner surface.The bi-directional under square wave pulse magnetic field coil, will be in a direction perpendicular to the measuring tube axis to produce a magnetic field of magnetic flux density of B work.At this point, if a certain electrical conductivity of liquid flowing through the measuring tube, will cut magnetic induction electromotive force E.Electromotive force E is proportional to the magnetic flux density B, sounding pipe diameter d, and V is the product of the average flow.Electromotive force E (traffic signal) by the detection electrode and through the cable to the converter.Converter will flow signal amplification processing, can display the fluid flow, and can output pulse, analog signals, such as current used for flow control and regulation.
E＝KBdV
Type: the E -- -- as the electrode signal voltage (V)
B -- - magnetic flux density (T)
D - tube inner diameter measurement (m)
V -- - the average flow velocity (m/s)
Type of K, d is constant, due to the exciting current is constant current, therefore, B is constant, by E = KBdV, volume flow rate Q is proportional to the signal voltage E, the velocity of the induction signal voltage E and a linear relationship with the volume flow rate Q.Therefore, as long as the measured E can determine the flow Q, this is the basic working principle of electromagnetic flowmeter.
By E = KBdV knowable, the medium of the flow temperature, density, pressure, conductivity, liquid-solid two-phase fluid parameters such as composition of liquid-solid ratio does not affect the measurement result.As for flow state should accord with axisymmetric flow (e.g., laminar or turbulent) will not affect the measurement result.So say electromagnetic flowmeter is a kind of volume flowmeter.For manufacturers and users, as long as the actual calibration with ordinary water can be measured after any other conductive fluid volume, and does not need to make any correction, this is a prominent advantages of electromagnetic flowmeter, is don't have any other flowmeter.The measuring tube without activity and choke components, so almost no pressure loss, and has high reliability.
Type: the E -- -- as the electrode signal voltage (V)
B -- - magnetic flux density (T)
D - tube inner diameter measurement (m)
V -- - the average flow velocity (m/s)
Type of K, d is constant, due to the exciting current is constant current, therefore, B is constant, by E = KBdV, volume flow rate Q is proportional to the signal voltage E, the velocity of the induction signal voltage E and a linear relationship with the volume flow rate Q.Therefore, as long as the measured E can determine the flow Q, this is the basic working principle of electromagnetic flowmeter.
By E = KBdV knowable, the medium of the flow temperature, density, pressure, conductivity, liquid-solid two-phase fluid parameters such as composition of liquid-solid ratio does not affect the measurement result.As for flow state should accord with axisymmetric flow (e.g., laminar or turbulent) will not affect the measurement result.So say electromagnetic flowmeter is a kind of volume flowmeter.For manufacturers and users, as long as the actual calibration with ordinary water can be measured after any other conductive fluid volume, and does not need to make any correction, this is a prominent advantages of electromagnetic flowmeter, is don't have any other flowmeter.The measuring tube without activity and choke components, so almost no pressure loss, and has high reliability.
Five, product selection
1, the range scope confirmation:
General industrial use electromagnetic flowmeter flow velocity measured medium hair 2 ~ 4 m/s advisable, under special circumstances, the minimum flow rate should not be less than 0.1 m/s, the highest no 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:
General industrial use electromagnetic flowmeter flow velocity measured medium hair 2 ~ 4 m/s advisable, under special circumstances, the minimum flow rate should not be less than 0.1 m/s, the highest no 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: traffic (/ h)
D: pipe diameter (m) V: velocity (m/h) of the electromagnetic flowmeter range Q volume flow quantity should be greater than expected, the flow of the normal value with 50% of the full range of high scale slightly greater than the flowmeter is advisable.
D: pipe diameter (m) V: velocity (m/h) of the electromagnetic flowmeter range Q volume flow quantity should be greater than expected, the flow of the normal value with 50% of the full range of high scale slightly greater than the flowmeter is advisable.
Electromagnetic flowmeter flow range query
| Inside diameter (mm) | 10 | 15 | 20 | 25 | 32 | 40 | 50 | 65 |
| Qmin（m3/h） | 0.0283 | 0.0636 | 0.12 | 0.176 | 0.29 | 0.452 | 0.7 | 1.19 |
| Qmax（m3/h） | 4.24 | 9.54 | 16.96 | 26.5 | 43.42 | 67.85 | 106.0 | 179.0 |
| Inside diameter (mm) | 80 | 100 | 125 | 150 | 200 | 250 | 300 | 350 |
| Qmin（m3/h） | 1.8 | 2.82 | 4.41 | 6.36 | 11.3 | 17.6 | 25.4 | 34.6 |
| Qmax（m3/h） | 271.0 | 424.0 | 662.0 | 954.0 | 1690 | 2650 | 3810 | 5190 |
| Inside diameter (mm) | 400 | 450 | 500 | 550 | 600 | 700 | 800 | 900 |
| Qmin（m3/h） | 45.2 | 57.2 | 77.6 | 85.5 | 101.0 | 138.0 | 180.0 | 229.0 |
| Qmax（m3/h） | 6780 | 8570 | 10600 | 12800 | 15200 | 20700 | 27100 | 34300 |
| Inside diameter (mm) | 1000 | 1100 | 1200 | 1400 | 1600 | 1800 | 2000 | 2200 |
| Qmin（m3/h） | 282.0 | 342.0 | 407.0 | 554.1 | 732.7 | 916.0 | 1131.0 | 1368.4 |
| Qmax（m3/h） | 42400 | 51300 | 61000 | 83121 | 108566 | 137404 | 169635 | 205258 |
2, reference lining material:
| The lining material | The main performance | The highest temperature | Scope of application | ||
| A shape | The separation type | ||||
| teflon （F4） | 1, is the student can be one of the most stable plastic, boiling hydrochloric acid, sulfuric acid, nitric acid and aqua regia, also have strong alkali and various solvents.Don't three chlorine fluoride, high temperature resistant chlorine, high-speed liquid fluoride, fluoride liquid oxygen, ozone corrosion. 2, wear-resisting performance is better than polyurethane rubber. 3, ability to resist negative pressure than neoprene. | 70 ℃ | 100 ℃ 150 ℃ ( Special order) | 1, strong acid, alkali and other corrosive medium 2, health, type of medium | |
| Same as above | |||||
| Poly perfluorinated ethylene-propylene class ene (F46) | Suitable temperature limit is ptfe Ethylene is low, but the cost is low. | 70 ℃ | 80 ℃ | ||
| Poly (neoprene | 1, has excellent flexibility, high break strength, wear-resisting performance is good. 2, generally low concentration acid resistance, alkali, salt corrosion medium, not the oxidation resistance of medium corrosion. | 80 ℃ 120 ℃ ( Special order) | Water, sewage and mud pulp weak up to wear and tear | ||
| Polyurethane rubber | 1, wear-resisting performance is extremely strong 2, poor corrosion resistance | 80 ℃ | Neutral strong wear of slurry, coal slurry and mud | ||
3, the choice of electrode material:
| Electrode materials | Corrosion resistance and wear resistance |
| Stainless steel 0CR18NI12MO2TI | Used for industrial water, water, sewage with weak corrosive medium, such as applicable to petroleum, chemical industry, iron and steel industries and municipal, environmental protection and other fields. |
| Hartz alloy B | Below boiling point for all the concentration of hydrochloric acid have good corrosion resistance, resistant to sulfuric acid, phosphoric acid, hydrofluoric acid, organic acids and other non chloride acid, alkali, corrosion of non oxidizing salt solution. |
| Hartz alloy C | Non oxidizing acid such as nitric acid, mixed acid, or a combination of chromic acid and sulfuric acid medium corrosion, oxidation resistance and salts such as Fe++ +, Cu++ or contain other antioxidant corrosion, such as higher than normal temperature hypochlorite solution, the corrosion of the water. |
| titanium | The sea, all kinds of chloride and hypochlorite, oxidizing acid (including fuming sulfuric acid), organic acid, alkali corrosion.Not a pure resistance reducing acid such as sulfuric acid, hydrochloric acid corrosion, but contains antioxidants such as acid (such as nitric acid, Fe++ +, Cu++), the corrosion is greatly reduced. |
| tantalum | It has excellent corrosion resistance, and glass is similar.Except hydrofluoric acid, fuming sulfuric acid, alkali, almost all the chemical can medium (including the boiling point of 150 ℃ hydrochloric acid, nitric acid and sulfuric acid) corrosion.In alkali corrosion. |
| Platinum/iridium alloy | Can almost all chemical medium, but does not apply to aqua regia and ammonium salt. |
| Stainless steel coated with tungsten carbide | Used for non-corrosive, strong wear medium. |
| Note: due to the variety of medium, the corrosion resistance and affected by complex factors such as temperature, concentration, flow velocity and change, so the data in this table is for reference only, the user should choose according to actual situation, when necessary tendency to choose the corrosion test of material, such as coupon test. | |
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