The hygienic electromagnetic flowmeter adopts a new type of hygienic lining material and lining process, which meets the hygiene requirements of the food industry.

Manufacturer of hygienic electromagnetic flowmeter

Sanitary electromagnetic flowmeter is a flow measuring instrument specifically used in industries with high hygiene requirements such as food, pharmaceuticals, and beverages.

The use of new sanitary lining materials prevents the accumulation of residual measuring media in the measuring tube.
·Adopting a quick connection scheme, the electromagnetic flowmeter is easy to disassemble, maintain, and clean.
·Using a 16 bit embedded microprocessor for signal processing, it has high integration, fast operation speed, high calculation accuracy, and fully digitized signals
Characteristics such as strong anti-interference ability and reliable measurement.

Working principle of sanitary electromagnetic flowmeter

The working principle of electromagnetic flowmeter is based on Faraday’s law of electromagnetic induction. In an electromagnetic flowmeter, the conductive medium inside the measuring tube is equivalent to a method
The conductive metal rod in the Faraday test generates a constant magnetic field with two electromagnetic coils at the upper and lower ends. When a conductive medium flows through, an induced voltage is generated. The induced voltage generated by measuring the two electrodes inside the pipeline. The measuring pipeline achieves electromagnetic isolation from the fluid and measuring electrodes through non-conductive lining (rubber, Teflon, etc.).

Main advantages of sanitary electromagnetic flowmeter

1) The sensor structure of an electromagnetic flowmeter is simple, with no movable parts inside the measuring tube and no throttling components that hinder fluid flow. So when the fluid passes through the flowmeter, it will not cause any additional pressure loss, making it one of the flow meters with the lowest operating energy consumption.
2) It can measure the flow rate of contaminated media, corrosive media, and suspended liquid-solid two-phase flow. This is because there are no obstructing flow components inside the instrument measuring tube, and only the inner lining and electrodes of the measuring tube are in contact with the measured fluid. The material can be selected according to the properties of the measured fluid. For example, using polytetrafluoroethylene or polytetrafluoroethylene as lining can measure various corrosive media such as acids, alkalis, salts, etc; The use of wear-resistant rubber as an inner lining is particularly suitable for measuring liquid-solid two-phase flows such as slurry and cement slurry with solid particles and high wear, as well as various suspended liquids such as fibrous liquids and pulp.
3) Electromagnetic flowmeter is a volumetric flow measurement instrument that is not affected by the temperature, viscosity, density, or conductivity (within a certain range) of the measured medium during the measurement process. Therefore, after being calibrated with water, electromagnetic flow meters can be used to measure the flow rate of other conductive liquids.
4) The output of an electromagnetic flowmeter is only proportional to the average flow velocity of the measured medium, and is independent of the flow state under symmetric distribution (laminar or turbulent). So the range of electromagnetic flow meters is extremely wide, with a measurement range of up to 100:1, and some even have an operational flow range of up to 1000:1.
5) Electromagnetic flowmeter has no mechanical inertia, sensitive response, can measure instantaneous pulsating flow, and can also measure flow in both positive and negative directions.
6) The diameter range of industrial electromagnetic flow meters is extremely wide, ranging from a few millimeters to several meters, and there are already real flow calibration equipment with a diameter of up to 3m in China, laying the foundation for the application and development of electromagnetic flow meters.

‌ sanitary electromagnetic flowmeter ‌ buy attention to the problem

1, accuracy level and function
The performance of general-purpose EMF on the market is quite different, some with high precision and more functions, and some with low precision and simple functions. The basic error of the hygienic electromagnetic flowmeter with high accuracy is (±0.5% ~ ±1%) R, and the instrument with low accuracy is (±1.5% ~ ±2.5%) FS, and the price difference between the two is 1 to 2 times. Therefore, the measurement accuracy requirements are not very high places (such as non-trade accounting only for the purpose of control, only require high reliability and good repeatability of the place) the selection of high-precision instruments is economically uneconomical.
Some models of sanitary electromagnetic flowmeters claim to have higher accuracy, the basic error is only (±0.2% ~ ±0.3%) R, but there are strict installation requirements and reference conditions, such as the ambient temperature of 20 ~ 22 ° C, the length of the front and back straight pipe section is required to be greater than 10D and 3D (usually 5D and 2D). It is even proposed that the flow sensor should be integrated with the front and rear straight tubes for real flow calibration on the flow standard device to reduce the impact of clamping. Therefore, when comparing a variety of models, do not simply look at high indicators, but read the manufacturer’s samples or instructions in detail for comprehensive analysis.
The function of EMF on the market is also very different, simple is just to measure one-way flow, only output analog signal to drive the post-meter; Multifunctional sanitary electromagnetic flowmeter has bidirectional flow measurement, range switching, upper and lower limit flow alarm, air pipe and power cut alarm, small signal cutting, flow display and total calculation, automatic check and fault self-diagnosis, communication with the host computer and motion configuration. The serial digital communication function of some models of meters can choose a variety of communication interfaces and special chip (ASIC) to connect to HART protocol system, PROFTBUS, Modbus, CONFIG, FF fieldbus, etc.
2 ‘flow rate, full flow rate, range and caliber
The diameter of the selected sanitary electromagnetic flowmeter is not necessarily the same as the diameter of the pipe, and should be determined by the flow rate. Process industry transport water and other liquids with different viscosity, the pipeline flow rate is generally the economic flow rate of 1.5 ~ 3m/s. EMF is used on such pipes, and the sensor caliber is the same as the pipe diameter.
EMF full flow rate when the liquid flow rate can be selected in the range of 1 ~ 10m/s, the range is relatively wide. The upper flow rate is in principle unlimited, however it is generally recommended not to exceed 5m/s, unless the lining material can withstand flow erosion, practical applications rarely exceed 7m/s, and more rarely exceed 10m/s. The flow rate limit of full degree flow is generally 1m/s, and some models of meters are 0.5m/s. In some new construction projects with low flow at the initial stage of operation or in the pipe system with low flow rate, from the perspective of measurement accuracy, the instrument diameter should be changed to less than the pipe diameter and connected with reducing pipe.
For fluids with easy adhesion, deposition, scaling and other substances, the flow rate is not less than 2m/s, and it is best to increase to 3 ~ 4m/s or above, to play a role in self-cleaning and preventing adhesion deposition. For abrasive fluids such as pulp, the usual flow rate should be lower than 2 ~ 3m/s to reduce the wear of the lining and electrode.
In the measurement of low conductivity liquid close to the threshold (that is, the lower limit), as far as possible to select a low flow rate (less than 0.5 ~ 1m/s), flow noise will increase due to the increase of flow rate, and the output wobble phenomenon.
EMF range is relatively large, usually not less than 20, with automatic range switching function of the instrument, can exceed 50 ~ 100. The caliber of styling products that can be provided in China ranges from 10mm to 3000mm, and the actual application is still mostly small and medium-sized caliber, but compared with most other principle flow meters (such as positive displacement, turbine, vortex or Coriolis mass, etc.), large caliber meters occupy a larger proportion. Among the nearly 10,000 meters of an enterprise, the small caliber below 50mm, the medium caliber from 65 to 250mm, the large caliber from 300 to 900mm, and the large caliber above 1000mm account for 37%, 45%, 15% and 3%, respectively.
3, liquid conductivity
The premise of using EMF is that the liquid under test must be conductive and cannot fall below the threshold (i.e. the lower limit). Conductivity below the threshold will produce a measurement error or even can not be used, exceeding the threshold even if the change can be measured, indicating that the error changes little, the general EMF threshold between 10-4 ~ (5×10-6) S/cm, depending on the model. When used, it also depends on the length of the flow signal line between the sensor and the converter and its distributed capacitance, and the signal line length corresponding to the electrical conductivity is usually specified in the manufacturer’s manual. Instruments with non-contact capacitance-coupled large-area electrodes can measure liquids with conductivity as low as 5×10-8 s /cm.
The conductivity of industrial water and its aqueous solution is greater than 10-4S/cm, the conductivity of acid, alkali and salt solution is between 10-4 and 10-1S/cm, and there is no problem in use, and there is no problem in low-degree distilled water for 10-5S/cm. Petroleum products and organic solvents can not be used if the conductivity is too low. Table 1 lists the electrical conductivity of several liquids. From the data found that some pure liquid or aqueous solution conductivity is low, it is considered that it can not be used, but the actual work will encounter the situation of containing impurities and can be used, such impurities increase the conductivity. For aqueous solution, the conductivity in the data is measured in the laboratory with the proportion of pure water. The actual aqueous solution may use the proportion of industrial water, and the conductivity will be higher than that found, which is also conducive to flow measurement.