Wedge Flow meterIt is a flow measurement instrument designed based on the principle of differential pressure. Its core component is a V-shaped wedge structure throttling element, which calculates the flow rate by measuring the pressure difference generated when the fluid flows through the wedge. It changes the fluid flow cross-section through a V-shaped wedge block. When the medium flows through the wedge block, a high-pressure zone is formed on the upstream side and a low-pressure zone is formed on the downstream side. The differential pressure value is proportional to the square of the fluid flow rate. The design with its smooth top angle facing downwards can avoid stagnant flow of suspended particles or high viscosity fluids upstream of the throttling element, ensuring measurement stability. The instrument structure is divided into integral and separate types, with connection methods including flange, welding, threading, and clamp type. The pressure tapping methods include ordinary tapping and flange sealing tapping, which are suitable for different working conditions.
Here isWedge Flow meterDetailed components and functional analysis of:
1、 Core measuring components
Wedge shaped throttling component
Structure: Composed of two symmetrical wedge-shaped blocks, fixed in the center of the pipeline, forming a tapered flow cross-section.
Function:
When the fluid passes through the wedge-shaped block, a pressure difference is generated, and the magnitude of the pressure difference is proportional to the square of the flow rate.
Wedge design can reduce fluid wear on throttling components, especially suitable for media containing particles.
Material: Stainless steel (such as 316L), Hastelloy, or ceramics are usually used to adapt to corrosive or high-temperature media.
Pressure tapping device
High pressure tap: located upstream of the wedge block, measures the pressure of the fluid before entering the throttling element.
Low pressure tap: located downstream of the wedge block, measures the pressure of the fluid after passing through the throttling element.
Design points:
The pressure tapping port should be perpendicular to the inner wall of the pipeline to avoid eddy current interference.
The diameter is usually 1/10 of the inner diameter of the pipeline to reduce the risk of blockage.
2、 Differential pressure measurement system
Differential pressure transmitter
Function: Convert the pressure difference between the high-pressure tap and the low-pressure tap into an electrical signal (such as 4-20mA).
Key parameters:
Range: Designed based on medium flow rate and pressure difference to ensure measurement accuracy.
Accuracy level: usually 0.1% or 0.075%, meeting the needs of industrial metrology.
Type: Intelligent differential pressure transmitter supports digital communication (such as HART protocol) for remote debugging.
triple valve manifold
Composition: Includes two shut-off valves and one balancing valve.
Function:
Globe valve: isolates differential pressure transmitter from pipeline for easy maintenance or calibration.
Balance valve: Balance the pressure on the high and low pressure sides to prevent damage to the transmitter diaphragm.
Material: Consistent with the pipeline material, usually stainless steel.
3、 Pipeline and connecting components
Measurement pipeline
Material: Choose carbon steel, stainless steel, or lining anti-corrosion material (such as PTFE) according to the characteristics of the medium.
Requirements for straight pipe section:
The length of the upstream straight pipe section is ≥ 10 times the diameter of the pipeline, and the downstream section is ≥ 5 times the diameter of the pipeline to eliminate the influence of eddy currents.
Special working conditions (such as elbows and valves) require increasing the length of straight pipe sections or installing flow adjusters.
flange connection
Type: butt welding flange, socket welding flange or threaded flange, selected according to the pressure rating of the pipeline.
Sealing: Metal wrapped gaskets or PTFE gaskets are used to ensure no leakage.
4、 Auxiliary components
Temperature compensation device (optional)
Function: Measure medium temperature, correct density fluctuations caused by temperature changes, and improve flow measurement accuracy.
Type: Thermistor (PT100) or thermocouple, installed upstream of the pipeline.
Pressure compensation device (optional)
Function: Measure medium pressure, correct density fluctuations caused by pressure changes, suitable for gas or steam flow measurement.
Type: Absolute pressure transmitter or gauge pressure transmitter.
Display and recording instrument
Function: Convert differential pressure transmitter signals into flow values and display, record, or transmit data.
Type:
Local display instrument: supports multi parameter display such as flow rate, temperature, pressure, etc.
Flow integrator: Built in flow calculation program, capable of outputting cumulative flow, instantaneous flow, etc.
PLC/DCS system: realize remote monitoring and automation control.
5、 Special design (for complex working conditions)
Anti blocking design
Applicable scenarios: Contains solid particles or high viscosity media.
measures
Install a filter or blowing device on the pressure port to prevent blockage.
Spray wear-resistant coating (such as tungsten carbide) on the surface of the wedge-shaped block to extend its service life.
Self cleaning function
Principle: Clean the sediment on the surface of the wedge-shaped block by regular backwashing or vibration device.
Application: Industries prone to scaling, such as sewage treatment and papermaking.
6、 Key points for installation and maintenance
Horizontal installation: Ensure that the wedge block is perpendicular to the pipeline axis to avoid gravity affecting measurement accuracy.
Vertical installation: only suitable for low flow media, to prevent gas or solid particle accumulation.
Regular calibration: Calibrate every 6-12 months, reducing high-precision scenarios to 3-6 months.
Clean the pressure tap: Check and clean the pressure tap every 3 months to prevent blockage.