Explosion proof electromagnetic flowmeter with enclosed pipeline

Explosion proof electromagnetic flowmeter for closed pipelines, mainly used to measure the volumetric flow rate of conductive liquids and slurries in closed pipelines. Such as water, sewage, mud, pulp, various acids, alkalis, salt solutions, food slurries, etc., are widely used in industries such as petroleum, chemical, metallurgical, textile, food, pharmaceutical, papermaking, as well as environmental protection, municipal management, water conservancy construction and other fields.

1、 Instrument Introduction:

Explosion proof electromagnetic flowmeter is installed in flammable and explosive environments, which has an additional explosion-proof function compared to ordinary electromagnetic flowmeters, and the shell material is better than ordinary ones. It is an induction instrument that measures the volume flow rate of conductive medium inside a tube based on Faraday's law of electromagnetic induction. It uses embedded microcontroller technology to achieve digital excitation, and adopts CAN fieldbus on the electromagnetic flowmeter. It belongs to the domestic * and the technology has reached the * level. In addition to measuring the flow rate of general conductive liquids, flow meters can also measure the volumetric flow rate of liquid-solid two-phase flow, high viscosity liquid flow, and salt, strong acid, and strong alkali liquids.

2、 Working principle:

The explosion-proof electromagnetic flowmeter is equipped with a pair of detection electrodes on the pipe wall perpendicular to the axis of the measuring tube and the magnetic field lines based on Faraday's electromagnetic induction principle. When the conductive liquid moves along the axis of the measuring tube, it cuts the magnetic field lines and generates an induced potential. This induced potential is detected by the two detection electrodes, and the value is proportional to the flow rate. Its value is E=KBVD equation:

E - Induced potential;

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

B - Magnetic induction intensity;

V - average flow velocity of conductive liquid;

D - electrode spacing; (Measuring the inner diameter of the tube)

The sensor uses the induced potential E as a flow signal, which is transmitted to the converter. After amplification, transformation, filtering, and a series of digital processing, the instantaneous and cumulative flow rates are displayed on a backlit dot matrix LCD. The converter has 4-20mA output, alarm output and frequency output, and is equipped with communication interfaces such as RS-485, and supports HART and MODBUS protocols.

IIIExplosion proof electromagnetic flowmeter with enclosed pipelineApplication scope:

Explosion proof electromagnetic flowmeter is mainly used to measure the volumetric flow rate of conductive liquids and slurries in closed pipelines. Such as water, sewage, mud, pulp, various acids, alkalis, salt solutions, food slurries, etc., are widely used in industries such as petroleum, chemical, metallurgical, textile, food, pharmaceutical, papermaking, as well as environmental protection, municipal management, water conservancy construction and other fields.

4、 Advantages:

1. The instrument structure is simple, reliable, without movable parts, and has a long working life;

2. No flow blocking components, no pressure loss or fluid blockage phenomenon;

3. No mechanical inertia, fast response, good stability, can be applied to automatic detection, adjustment, and program control systems;

4. The measurement accuracy is not affected by the type of measured medium and its physical parameters such as temperature, viscosity, density, pressure, etc;

5. Different combinations of PTFE or rubber lining materials and electrode materials such as Hc, Hb, 316L, Ti can adapt to the needs of different media;

6. There are various flow meter models available, including pipeline type and plug-in type;

7. Using EEPROM memory, the measurement and operation data storage protection is safe and reliable;

8. It has two types: integrated and separated;

9. High definition LCD backlit display.

5Explosion proof electromagnetic flowmeter with enclosed pipelinePerformance indicators:

Instrument accuracy: pipeline type 0.5 level, 1.0 level; Insertion type 2.5 level;

Measurement medium: various liquid and liquid-solid two-phase fluids with conductivity greater than 5 μ S/cm;

Flow velocity range: 0.2-8m/s;

Work pressure: 1.6MPa;

Environmental temperature: -40 ℃ to+50 ℃;

Medium temperature: PTFE lining ≤ 180 ℃.

Rubber material lining ≤ 65 ℃;

Explosion proof mark: Exmibd Ⅱ BT4;

Explosion proof certificate number: GYB01349;

External magnetic interference: ≤ 400A/m;

Shell protection: integrated type: IP65;

Detached type: Sensor IP68 (5 meters underwater, with rubber lining) Converter IP65;

Output signal: 4-20mA.DC, load resistance 0-750 Ω;

Communication output: RS485 or CAN bus;

Electrical connection: M20 × 1.5 internal thread, φ 10 cable hole;

Power supply voltage: 90-220V.AC, 24 ± 10% V.DC;

Maximum power consumption: ≤ 10VA.

6、 Structural form:

1. Sensor:

The sensor mainly consists of a measuring conduit, measuring electrodes, excitation coils, iron cores, magnetic yokes, and a housing.

a、 Measurement catheter: composed of stainless steel catheter, lining, and connecting flange, it is a carrier for measuring the on-site working conditions of the measured liquid.

b、 Measurement electrode: a pair of electrodes installed on the inner wall of the measurement catheter, perpendicular to the axial flow direction, to generate signals for the measured liquid.

c、 Excitation coil: The upper and lower excitation coils that generate a magnetic field inside the measuring conduit.

d、 Iron core and magnetic yoke: Introduce the magnetic field generated by the excitation coil into the liquid and form a magnetic circuit.

e、 Shell: Instrument outer packaging.

2. Converter:

It is an intelligent secondary meter that amplifies and processes the flow signal. After being operated by a microcontroller, it can display the flow rate, cumulative measurement, and output signals such as pulses and analog currents for measuring or controlling fluid flow.

3. Product assembly form:

It is divided into two forms: one-piece and split type.

a、 Integrated: The sensor and converter are installed together.

b、 Split type: Sensors and converters are installed separately, forming a flow metering system through connecting cables.

c、 To meet the requirements of measuring different media, there are multiple choices for the lining and electrode materials of sensors.

7、 The main advantages are as follows:

1. The sensor structure of the 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 the internal flow components of the instrument measuring tube only come into contact with the inner lining and electrodes of the measuring tube, and their materials 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. It 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 a 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. 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.

8、 The main ones that still exist at present are:

1. Cannot be used to measure gases, vapors, and liquids containing large amounts of gas.

2. It cannot be used to measure liquid media with very low conductivity, such as petroleum products or organic solvents. Currently, electromagnetic flow meters are powerless.

3. Due to the limitations of the lining material and electrical insulation material of the measuring tube, it cannot be used for measuring high-temperature media; Without special treatment, it cannot be used for measuring low-temperature media to prevent insulation damage caused by condensation (frost) outside the measuring tube.

4. Easily affected by external electromagnetic interference.

9、 Selection and precautions for installation environment:

In order to ensure stable operation of the transmitter, the following requirements should be noted when selecting the installation environment:

1. Try to avoid ferromagnetic objects and specific equipment with strong electromagnetic fields (such as large motors, transformers, etc.) to prevent the magnetic field from affecting the working magnetic field and flow information of the sensor.

2. It should be installed in a dry and ventilated place as much as possible, and should not be installed in damp or water prone areas.

3. Avoid direct sunlight and rain as much as possible, and avoid environments with temperatures above 45 ℃ and relative humidity above 95.9%.

4. Choose a place that is easy to maintain and has convenient activities.

5. The flowmeter should be installed at the rear end of the water pump and must not be installed on the suction side; The valve should be installed on the downstream side of the flowmeter.

Notes:

1. Try to avoid ferromagnetic objects and equipment with strong electromagnetic fields as much as possible to prevent the magnetic field from affecting the working magnetic field and flow signal of the sensor.

2. It should be installed in a dry and ventilated place as much as possible, avoiding direct sunlight and rain. The ambient temperature should be between -20 and+60 ℃, and the relative humidity should be less than 85%.

3. There should be ample space around the flowmeter for easy installation and maintenance.

10、 How to choose the correct installation point for electromagnetic flowmeter:

1. Choose a straight pipe section filled with liquid, such as a vertical section of the pipeline (with a flow direction from bottom to top) or a horizontal pipeline filled with liquid (with the lowest point in the entire pipeline). During installation and measurement, non full pipe conditions must not occur;

2. The measurement position of the intelligent electromagnetic flowmeter should be selected at upstream locations greater than 5D and downstream locations with 3D straight pipe sections;

3. The selection of measurement points should be as far away as possible from equipment such as pumps and valves to avoid interference with the measurement;

4. The selection of measurement points should be as far away as possible from high-power radio stations, strong magnetic field interference sources, etc.

11、 Installation instructions:

1. The axis of the measuring electrode must be approximately horizontal;

2. The measuring pipeline must be filled with liquid;

3. The front of the flowmeter should have at least a 5 × D (D is the inner diameter of the flowmeter) straight pipe section, and the rear should have at least a 3 × D (D is the inner diameter of the flowmeter) straight pipe section; For the convenience of installation and disassembly, a pipeline expansion joint can be installed after the electromagnetic flowmeter;

4. The direction of fluid flow and the arrow direction of the flowmeter *;

5. Vacuum inside the pipeline can damage the lining of the flowmeter, so special attention should be paid;

6. There should be no strong electromagnetic field near the flowmeter;

7. There should be ample space near the flowmeter for installation and maintenance;

8. If there is vibration in the measuring pipeline, there should be fixed supports on both sides of the electromagnetic flowmeter;

9. When measuring mixed liquids of different media, the distance between the mixing point and the flowmeter should be at least 30 × D (D is the inner diameter of the flowmeter) in length;

10. For the convenience of cleaning and maintenance of the flowmeter in the future, a bypass pipeline should be installed, and the front 5D and rear 3D straight pipe sections of the electromagnetic flowmeter should be ensured;

11. If installing a flow meter with PTFE lining, the bolts connecting the two flanges should be tightened evenly with a torque wrench, otherwise it is easy to crush the PTFE lining.

12、 Installation requirements:

1. The flowmeter should be installed at the lower and vertically upward positions of the horizontal pipeline, avoiding installation at the highest and vertical points of the pipeline;

2. The electromagnetic flowmeter should be installed at the rising point of the pipeline;

3. Electromagnetic flow meters should be installed at the lower part of open discharge pipelines;

4. If the pipeline drop exceeds 5m, install an exhaust valve downstream of the electromagnetic flowmeter;

5. Control valves and shut-off valves should be installed downstream of the sensor, rather than upstream of the electromagnetic flowmeter;

6. Electromagnetic flowmeter cannot be installed at the inlet and outlet of the pump, it should be installed at the outlet of the pump;

7. The method of installing a flow meter in the measuring well.

13、 Precautions during installation:

1. The axis of the non measuring electrode must be approximately horizontal;

2. The measuring pipeline must be filled with liquid;

3. There should be at least a 5 * D (D is the inner diameter of the flow meter) straight pipe section in front of the flow meter, and at least a 3 * D (D is the inner diameter of the flow meter) straight pipe section in the back;

4. The direction of fluid flow and the arrow direction of the flowmeter *;

5. Vacuum inside the pipeline can damage the lining of the flowmeter, so special attention should be paid;

6. There should be no strong electromagnetic field near the flowmeter;

7. There should be ample space near the flowmeter for installation and maintenance;

8. If there is vibration in the measuring pipeline, there should be fixed supports on both sides of the flowmeter. When measuring mixed liquids of different media, the distance between the mixing point and the flowmeter should be at least 30 × D (D is the inner diameter of the flowmeter). To facilitate the cleaning and maintenance of the flowmeter in the future, a bypass pipeline should be installed.

14、 Main technical data:

1. Technical data of the whole machine and sensors

2. Converter technology data

3. Selection of lining

4. Selection of imported protective flanges and grounding flanges (or grounding rings)

5. Selection of electrodes

15、 Correct selection:

The selection of instruments is a very important task in instrument applications. Relevant data shows that 2/3 of instrument failures in practical applications are caused by incorrect selection or installation of instruments. Please pay special attention.

1. Collect data:

The composition of the fluid being tested;

Zui high traffic, Zui low traffic;

The highest work pressure;

Zui high temperature, Zui low temperature;

2. Range confirmation:

The flow rate of the medium measured by the general industrial electromagnetic flowmeter should be 2-4m/s. In special circumstances, the minimum flow rate should not be less than 0.2m/s, and the maximum flow rate should not be greater than 8m/s. If the medium contains solid particles, the commonly used flow rate should be less than 3m/s to prevent excessive friction between the lining and the electrode; For viscous fluids, the flow velocity can be chosen to be greater than 2m/s. A higher flow velocity helps to automatically eliminate the effect of viscous substances attached to the electrode, which is beneficial for improving measurement accuracy.

Under the condition that the range Q has been determined, the size of the flowmeter diameter D can be determined based on the range of flow velocity V mentioned above, and its value can be calculated by the following formula:

Q=πD2V/4

Q: Flow rate (㎡/h) D: Inner diameter of pipeline V: Flow rate (m/h)

The range Q of the electromagnetic flowmeter should be greater than the expected maximum flow value, while the normal flow value should be slightly greater than 50 of the flowmeter's full-scale scale.

3. Reference flow range:

16、 Selection Table:

1. Product: If there are model standards, please call directly to inquire about prices and learn more details!

2. If there are no product model specifications, please send the operating requirements, design drawings, and technical specifications to our company.

3. Product ordering requires parameters such as diameter (DN), nominal pressure (Mpa), temperature (℃), flow range (m3/h), medium name (such as water), connection method (clamp type, threaded type, flange type, clamping type, split type, insertion type, etc.).

4. Quotation confirmation: Our company provides a quotation list and technical standard specifications to the customer for confirmation. After both parties confirm the technical aspects, the contract will be drafted.

5. Quality requirements, quality standards, and conditions for suppliers to be responsible for quality: in accordance with relevant national quality standards.

After-sales service

1. From the date of contract signing, our company provides free maintenance and upkeep services for the products provided, and promises lifelong repair services;

2. Jiangsu Desen Instrument Co., Ltd. will regularly communicate with customers to understand the usage of the product and solve any problems that arise during their use, providing free services;

3. During the warranty period, if there is any man-made damage, our company is responsible for repairing it and collecting the repair costs incurred;

4. If there are quality problems or dissatisfaction with the product, users can choose to return or exchange it unconditionally. The company does not charge any handling fees. If there are quality problems, the company will bear the round-trip shipping costs.