Insertion Turbine Flow Meter

Core Components and Operating Principle

• Insertion Probe (Sensor): This is the core component, typically a slender rod-shaped structure. The front end of the probe features micro-turbine blades, followed by a signal-sensing device (such as a magnetoelectric or Hall-effect sensor). When the probe is inserted into a fluid, the fluid drives the turbine to rotate, and the sensor converts the turbine’s rotational speed into electrical pulse signals.
• Mounting Bracket and Sealing Device: To safely insert the probe into the pipeline, a dedicated mounting bracket or flange is typically used, along with a ball valve and sealing device to prevent medium leakage during probe insertion or removal. Some designs even support pressurized installation and maintenance without stopping fluid flow.
• Converter (display instrument): Responsible for receiving the pulse signals generated by the probe, amplifying, shaping, counting, and calculating them, and finally converting the pulse frequency into instantaneous flow rate and cumulative flow rate. The converter can be integrated with the probe to form a one-piece design; it can also be installed separately and connected via a cable.

Main Features

• Easy installation without interrupting the pipeline: This is the most prominent advantage of the insertion turbine flowmeter. Simply drill a hole in the existing pipeline, install the connection fitting, and insert the probe, significantly reducing installation time and costs, making it particularly suitable for retrofit projects or sites where production cannot be halted.
• Suitable for large-diameter pipelines: For pipelines with larger diameters (typically DN200 or above), the insertion-type flowmeter offers significant cost advantages compared to full-bore pipeline-type flowmeters. It avoids the costs and complexity associated with purchasing and installing large flowmeters.
• Pressure-resistant installation and maintenance (select models): With specialized tools and ball valves, certain insertable turbine flow meters allow probe installation, inspection, or replacement without interrupting fluid flow or draining the pipeline, enhancing operational efficiency.
• Low pressure loss: Since only the probe extends into the fluid, it causes minimal obstruction, resulting in very low pressure loss.
• Flexibility: In some cases, the same probe may be suitable for pipes of different diameters by adjusting the insertion depth.

Limitations

• Measurement accuracy is significantly affected by flow field conditions: The probe of an insertion flowmeter measures the flow velocity at a specific cross-section or area within the pipe and does not fully represent the average flow velocity of the entire pipe. Therefore, its measurement accuracy highly depends on the uniformity of the flow field within the pipe. Installation in areas with significant fluid turbulence, such as elbows, valves, or pump outlets, can severely affect measurement accuracy. Typically, sufficient straight pipe sections (10–20D upstream and 5D or more downstream) are required to ensure accuracy.
• Not suitable for small-diameter pipes: In small-diameter pipes, the probe occupies too much of the flow area, causing significant fluid disturbance and hindering measurement.
• High requirements for fluid cleanliness: Turbine components and bearings are highly sensitive to impurities, particles, and fibers in the fluid, which can cause wear, blockages, or jams, affecting measurement performance and lifespan.
• Not suitable for media with excessively high viscosity: High-viscosity fluids can hinder the normal rotation of the turbine.
• Precise insertion depth of the probe: To ensure measurement accuracy, the insertion depth of the probe typically requires precise calculation and positioning based on the pipe diameter and fluid characteristics.

Applications

Insertion turbine flow meters are particularly suitable for applications requiring economical and convenient flow measurement in large-diameter pipes with certain fluid cleanliness requirements:

• Municipal water supply and drainage: Used to monitor flow in large-diameter municipal pipes.
• Agricultural irrigation: Water flow measurement in large-scale agricultural irrigation systems.
• Industrial cooling water systems: Monitoring the flow of circulating cooling water or general industrial water.
• Large HVAC systems: Water flow monitoring in central air conditioning systems.
• Non-trade settlement flow monitoring: In scenarios where accuracy requirements are not as stringent as trade settlement but where approximate flow data is still needed.