Insertion Magnetic Flow Meter

Core Components and Working Principle

• Sensor (insertion probe): This is the core component of an insertion electromagnetic flowmeter. It typically consists of a probe with electrodes and excitation coils, which is directly inserted into the flowing liquid pipeline through a sealed interface. When conductive liquid flows through the sensor’s sensing area, it follows Faraday’s law of electromagnetic induction, generating an induced electromotive force proportional to the flow velocity.
• Converter: Similar to other types of electromagnetic flowmeters, the insertion-type electromagnetic flowmeter also requires a converter to receive the weak signal generated by the sensor, amplify, process, and calculate it, and finally display the instantaneous flow rate and cumulative flow rate, while outputting the corresponding signal. The converter can be integrated (directly connected to the sensor) or separate (connected via a cable).
• Mounting bracket or ball valve: To enable “pressurized drilling” or installation and maintenance without interrupting fluid flow, insertable electromagnetic flowmeters typically come with a special mounting bracket or ball valve.

Key Features

• Easy installation without interrupting pipeline flow: This is the greatest advantage of insertable electromagnetic flowmeters. On existing pipelines, simply drill a hole and install the connection seat to insert the sensor for measurement, significantly reducing installation time and costs. This is particularly suitable for retrofitting old pipelines or applications where production cannot be halted.
• Suitable for large-diameter pipelines: For large-diameter pipelines (e.g., DN300 and above), insertable electromagnetic flowmeters offer lower costs and easier installation compared to traditional flanged electromagnetic flowmeters.
• Pressure-resistant installation and maintenance (requires specialized tools): Some models of insertable flow meters, when used with specialized installation tools, can be installed or have their probes removed for maintenance without stopping the flow of the medium or reducing pressure, greatly improving production efficiency.
• Cost-effectiveness: For large-diameter pipelines, the cost of insertable electromagnetic flow meters is typically significantly lower than that of flanged electromagnetic flow meters of the same diameter.
• Low pressure loss: Since the probe section causes minimal obstruction to the fluid, the resulting pressure loss is very small.

Limitations

• Measurement accuracy affected by flow field: Since the sensor is insertable, its measurement accuracy may be influenced by the uniformity of the flow field distribution within the pipeline. For example, near pipeline bends, valves, or pump outlets, the flow field may be non-uniform, affecting measurement results. Therefore, it is generally recommended to install the meter on a sufficiently long straight pipe section.
• Probe immersion depth affects accuracy: The probe insertion depth must be precisely controlled to ensure measurement accuracy.
• Not suitable for small-diameter pipes: Insertion-type flow meters are generally not suitable for small-diameter pipes, as the probe occupies a significant portion of the flow area in small-diameter pipes, leading to greater fluid disturbance and pressure loss.
• Not suitable for viscous fluids or fluids containing a large amount of impurities: Viscous liquids or liquids containing a large amount of suspended particles may cause probe contamination or wear, affecting measurement performance.

Typical application scenarios

Insertion electromagnetic flowmeters are widely used in various scenarios requiring flow measurement in large-diameter pipes, especially in conditions where shutdown or renovation is inconvenient:

• Water supply and drainage: Monitoring of main pipeline flow in urban water supply networks and wastewater treatment plants.
• Agricultural irrigation: Flow measurement in large-scale irrigation pipelines.
• Industrial water use: Large-flow water treatment systems in industrial production.
• HVAC systems: Monitoring of water flow in large central air conditioning systems.