Plug in vortex flowmeterIt is an instrument designed specifically for measuring flow in large-diameter pipelines, based on the Karman vortex street principle. When a fluid flows through a non streamlined vortex generator in a pipeline, two columns of vortices with opposite rotation directions will be alternately generated on both sides, and the frequency of vortex detachment is proportional to the fluid flow velocity. By detecting the vortex frequency through a piezoelectric sensor and converting it into an electrical signal proportional to the flow rate (such as 4-20mA current or pulse signal), flow measurement can be achieved.
Its core advantage lies in adapting to scenarios with large pipe diameters. The traditional full tube vortex flowmeter is difficult to apply when measuring pipe diameters exceeding 300mm due to reduced instrument coefficients, decreased resolution, and complex installation. However, the plug-in design effectively solves this problem by inserting the measuring head into the center point of the pipeline, only measuring local flow velocity, and then combining algorithms to calculate the overall flow rate. The device has a compact structure, light weight, low manufacturing cost, and supports continuous installation and disassembly, making it easy to maintain and verify in the later stage. Its pressure loss is extremely small, and its impact on large-diameter pipelines can be ignored. At the same time, the calibration process is simple, only requiring calibration of the measuring head instrument coefficient, without the need for large calibration devices.
Plug in vortex flowmeterThe components of:
1、 Core testing components
Vortex generator (vortex generator)
Function: As the core component of the flowmeter, its shape (such as triangle, cylinder, trapezoid, etc.) directly affects the generation frequency and stability of the vortex street. When fluid flows through a generator, Karman vortex streets (regularly arranged vortices) alternate on both sides.
Design requirements: Symmetry, anti fouling ability, and corrosion resistance are required. Common materials include stainless steel or special alloys to meet the measurement needs of different media such as gas, liquid, and steam.
Sensor (detection probe)
Type:
Piezoelectric sensor: It utilizes the charge output of piezoelectric crystals under the action of vortex pressure pulses to convert mechanical vibrations into electrical signals, with high sensitivity and anti-interference ability.
Strain gauge sensor: By detecting small deformations caused by vortex streets and converting them into resistance change signals, it is suitable for high temperature or strong vibration environments.
Hot wire sensor: indirectly detects the vortex frequency by measuring the effect of vortex street on the heat dissipation of the hot wire, commonly used for low flow velocity measurement.
Installation location: usually located downstream of the generator, about 1-3 times the diameter of the pipe from the center of the generator, to capture stable vortex signals.
2、 Signal processing unit
preamplifier
Function: Amplify and filter weak electrical signals output by sensors, eliminate noise interference, and improve signal quality.
Characteristics: It needs to have low noise, high gain, and wideband characteristics to adapt to signal processing requirements at different flow rates.
Signal conversion and processing circuit
Frequency voltage conversion: Convert vortex frequency signals into voltage or current signals for subsequent display and transmission.
Digital Signal Processing (DSP): further processing of signals through microprocessors, such as temperature compensation, linearization correction, flow calculation, etc., to improve measurement accuracy.
Communication interface: Supports protocols such as 4-20mA, RS485, HART, Modbus, etc., to achieve data exchange with the upper computer or automation system.
Display and operation module
Local display: Real time display of flow rate, temperature, pressure and other parameters through LCD or LED screens. Some models support cumulative flow query and fault code display.
Key operation: Provides functions such as parameter setting, range adjustment, zero calibration, etc., simplifying the on-site debugging process.
3、 Installation and support structure
Insert rod (probe rod)
Function: Fix the sensor inside the pipeline and ensure it is in full contact with the fluid.
Design requirements: Sufficient strength and corrosion resistance are required, and the length can be adjusted according to the pipeline diameter and installation depth, usually ranging from 1/3 to 1/2 of the pipe diameter.
Flanges or threaded connectors
Type:
Flange connection: suitable for large-diameter pipelines (DN50 and above), fixed by bolts, firmly installed and easy to disassemble.
Threaded connection: suitable for small-diameter pipelines (below DN50), threaded into the pipeline, easy to install but with high sealing requirements.
Sealing material: High temperature and corrosion-resistant materials such as fluororubber and silicone rubber are used to ensure long-term sealing reliability.
Anti vibration bracket
Function: Reduce the impact of external vibrations on the flowmeter, avoiding measurement errors or sensor damage caused by vibrations.
Installation position: usually fixed on pipeline supports or dedicated bases, isolated from the flowmeter body.
4、 Auxiliary function module
Temperature and pressure compensation module (optional)
Function: When measuring steam or gas, real-time compensation of flow rate is achieved through built-in temperature and pressure sensors, eliminating the influence of medium density changes on measurement results.
Application scenarios: Industrial processes that require high-precision measurement, such as steam metering, natural gas trade settlement, etc.
Protective shell
Function: Protect the internal electronic components of the flowmeter from environmental factors such as dust, moisture, and corrosive gases.
Protection level: usually up to IP65 or IP67, suitable for outdoor or harsh industrial environments.
Lightning protection and surge protector
Function: To prevent damage to the flowmeter caused by lightning strikes or power grid fluctuations, ensuring the safe operation of the equipment.
Installation location: usually integrated in the signal processing unit or power input terminal.