The core principle of a threaded vortex flow meter is the Kármán vortex street principle. When fluid passes a bluff body inside the meter, alternating vortices are generated downstream. The sensor detects the vortex frequency and calculates volumetric flow according to the relationship between vortex frequency and flow velocity.
USA VTON threaded vortex flow meters mainly consist of a measuring passage, bluff body, sensing components, and signal-processing electronics.
1. Fluid Passes the Bluff Body and Generates Vortices
When the medium enters the measuring passage, it flows around the bluff body.
Alternating vortices are generated downstream. Their shedding frequency has a defined relationship with fluid velocity, allowing the meter to determine flow.
This principle supports vortex measurement of steam, gases, and selected liquid applications.
2. The Sensor Detects Vortex Frequency
The internal sensor detects pressure, stress, or other changes associated with vortex shedding and converts them into an electrical signal.
The electronics process the signal and calculate flow velocity or volumetric flow based on the configured relationship.
For compressible media such as steam and gases, pressure and temperature compensation or calculation may be required when mass flow or standard-condition flow is needed.
3. Threaded Connection Determines the Installation Method
Compared with flanged designs, threaded connections can provide a relatively compact connection structure. Suitability should still be evaluated according to pressure, temperature, pipe size, and installation conditions.
The thread specification must match the pipeline. During installation, the flow direction should correspond to the arrow on the meter, while locations with severe vibration or pulsation should be avoided where possible.
Application Example
At a certain industrial compressed-air pipeline, flow monitoring was required in a relatively compact installation area with a threaded connection. The meter specification was determined according to compressed-air flow, pressure, and temperature, and the measured signal was transmitted to the control system.
Application Advice
Understanding the measurement principle does not replace proper selection. Flow range remains a key factor. For gas and steam applications, the meter should not be selected only according to pipe DN; actual flow, pressure, and temperature should also be checked.
