Smart Insertion Type Magnetic Flow Meter

The insertion type magnetic flow meter is an instrument designed based on Faraday’s law of electromagnetic induction to measure the flow of conductive liquids. Due to its simple structure, lightweight, easy installation, and low maintenance, this type of flow meter is widely used in petrochemical plants for measuring the volumetric flow of non-corrosive conductive liquids (such as water supply and drainage) in closed pipelines.

Methods for Measuring the Flow of Conductive Liquids in Large Pipelines

1. Electromagnetic Flow Meter

2. Orifice Plate Flow Meter (including concentric sharp-edge orifice plates, 1/4-circle orifice plates, etc.)—a standard flow measurement element with a simple structure, high accuracy, good repeatability, and long service life. However, it requires a long straight pipe section, causes pressure loss, has high flow velocity requirements, and is unsuitable for large-diameter pipelines.

3. Ultrasonic Flow Meter—a new non-contact flow measurement instrument that is being gradually promoted, but it is not suitable for installation in buried pipelines.

4. Vortex Flow Meter—another optional flow measurement instrument. However, its performance varies significantly in practical applications. It requires a strict straight pipe section and a minimum flow velocity, making it generally unsuitable for large buried pipelines.

Challenges in Measuring Large-Diameter Conductive Liquid Flow in Petrochemical Enterprises

In petrochemical plants, the large-diameter fluids in process units and utility systems mainly include fresh water, desalinated water, circulating water, wastewater, and seawater. These fluids and their pipeline installation have the following characteristics:

1. Large Pipe Diameter—some factories have circulating water pipelines with diameters as large as 1.8 to 2.0 meters. To save space, reduce pipe bridge loads, and prevent freezing, these pipelines are generally buried underground.

2. Low Flow Velocity and Fluctuating Flow Rates—due to the large flow volume, the system is designed for lower flow velocities to reduce long-term operational costs, but flow rates and velocities often vary.

3. Poor Water Quality—circulating water and wastewater contain varying levels of suspended solids or sediment.

4. Difficult Instrument Installation—flow meters are installed outside process boundaries, making it challenging to lay instrument pipelines and signal cables.

5. Accuracy Requirements—measurement accuracy should be sufficient for internal material balance and economic accounting.

Features of the Insertion Type Magnetic Flow Meter

1. Compact Sensor Design—the sensor (probe) is directly inserted into the pipeline, making it smaller, easier to install, and more cost-effective compared to conventional flanged electromagnetic flow meters.

2. Minimal Pressure Loss—the sensor insertion depth is only 10%–12.5% of the pipe diameter, making it particularly suitable for large-diameter flow measurement with an excellent cost-performance ratio.

3. No Blockage, No Wear, and Maintenance-Free

4. Submersible Sensor Option—the sensor can be made with an IP68 submersible design, ideal for buried pipeline installations.

5. Explosion-Proof Design Available

6. Stable Zero Point—outputs current and pulse signals with absolute zero stability.

7. Wide Flow Range—can measure flow velocities as low as 0.1 m/s (or even lower), with a minimum conductivity requirement of ≥20μS/cm.

8. Easy Installation—the sensor can be equipped with installation accessories for convenient on-site mounting.

9. Moderate Accuracy—typically ±1%.

Issues in Using Insertion Type Magnetic Flow Meters

1. Minimum Flow Velocity Considerations—although the meter can measure flow velocities as low as 0.1 m/s, users should still verify that the measured velocity ensures sufficient accuracy.

2. Straight Pipe Requirements—the flow meter requires at least 5D of straight pipe upstream and 3D downstream (D = nominal pipe diameter).

3. Sedimentation Risks—if sludge or sediment is present in the pipeline, the flow velocity should be high enough to prevent deposits. In cases where sediments might insulate the sensor, replaceable electrode sensors should be used for online maintenance.

4. Flow Variability—for systems with large flow variations or long-term low velocities below the meter’s minimum requirement, users should consider reducing the process pipe diameter or installing two meters in parallel (one large and one small).

5. Installation Orientation—like conventional electromagnetic flow meters, insertion meters should ideally be installed in vertical pipelines to prevent solid deposits on the electrodes and ensure oil separation from the measuring area. If installed in horizontal pipelines, the sensor’s electrodes should be aligned along the horizontal axis to prevent air bubbles from causing measurement errors.

Advantages of Electromagnetic Flow Meters Over Other Technologies

Accurate flow measurement is essential for conductive liquids, including general conductive liquids, strong acids, strong alkalis, and two-phase slurries such as mud, mineral slurry, and pulp. However, traditional vortex, turbine, swirl, and ultrasonic flow meters are often unsuitable due to low accuracy, high cost, or poor adaptability to harsh environments. In contrast, electromagnetic flow meters stand out for their high precision, strong vibration resistance, and corrosion resistance. Compared to conventional electromagnetic flow meters, intelligent insertion type magnetic flow meters feature a single-electrode design, allowing for a more compact sensor, broader application range, fewer sealing points, enhanced reliability, and improved quality assurance.