Annubar flow meter structure and working principle
The detection tube of the Annubar (average velocity tube) flowmeter adopts a diamond-shaped section. Thus, the separation point of the
fluid boundary layer is effectively controlled. Make its separation position independent of the Reynolds number. And can get a stable
flow coefficient. This improves the measurement accuracy of the flowmeter.
A flow meter consists of 5 basic parts (see Figure 1)
1. The static pressure outlet pipe can detect the static pressure of the back hole. Sent to the negative pressure chamber of the differential pressure transmitter.
2. The total pressure mean tube can measure the total pressure detected by the 4 upstream orifices. After automatic averaging. Positive pressure chamber for conveying differential pressure transmitter.
3. The static pressure hole is in the center of the backflow direction of the flowmeter. Responsible for the detection of static pressure.
4. The detection rod is the overall detection part of the flowmeter. It includes 4 total pressure holes. 1 static pressure hole. There are also a total pressure averaging tube and a static pressure lead-out tube inside.
5. Total pressure hole: It has 4 detection holes. It is determined according to the Chebyshev (Tchebycheff) formula. The 4 holes are distributed in 4 rings of equal cross-sectional area (2 half rings, 2 half circles). Facing the upstream of the fluid, it is responsible for detecting the total pressure at the standard points of each section.
Annubar flowmeter customization case 1: Large diameter water measurement
According to the needs of customers from Indonesia, they need to replace the original DN1800 and DN1200 Annubar flow meters. The measuring medium is water. Working Pressure 7 Bar, Working Temperature 70°C. Flow range is 15000 T(Met)/H.
Based on the drawings and measurement parameters provided by the user, we customized the replacement Annubar flow meter. The measurement effect is stable.
Annubar flow meter customization case 2: high temperature gas measurement
Customers from Malaysia need to measure the flow rate of high-temperature mixed gases at 800°C and 400°C. Hot air from the kiln, air composition and proportions: gaseous carbon dioxide, gaseous sulfur and arsenic.
According to the user’s measurement parameters, we customize high-temperature Annubar flow meters for them. Insert installation;316 stainless steel material. Working pressure range: <10bar; Maximum flow range: 0-80000 m³/h; Temperature: 800°C, Pipe diameter: 2500mm; 4~20mA output.
At the same time, we have also customized 800℃ and 400℃ high temperature pressure transmitters for users to perform pressure compensation for measurement.
