annubar flowmeter

Overview
The averaging tube is also known as the Annubar or Flute Tube. The averaging tube is developed based on the principle of pitot tube speed measurement. Due to its low pressure loss, low manufacturing cost, and easy installation and maintenance, it is widely used in various countries.
working principle
The measurement principle of the averaging tube is to divide the entire circular cross-section into multiple circular rings with equal unit areas (with a circle in the middle). The detection rod of the averaging tube is a hollow metal tube.
annubar flowmeterScope of Application
1. Nominal diameter: 80mm ≤ DN ≤ 6000mm
2. Nominal pressure: PN ≤ 25MPa
3. Medium temperature: t ≤ 650 ℃
4. Accuracy level: Level 1, Level 1.5, Level 2.5

annubar flowmeterFeatures:

The internal quadratic average structure of 1 * provides high accuracy (reading ± 1%) and high repeatability (± 0.1%).

The outer impact tube is made of a single piece of material without welding, which naturally has the highest strength compared to similar products welded by a double body structure. It is also easy to choose materials that are resistant to high temperatures and corrosion.

The stable structure of the honeycomb hexagonal structure produces a beam distribution shape of *, ensuring the stability of the low-pressure signal and generating a higher differential pressure than similar products, improving the range ratio.

4. Suitable for square or rectangular pipes.

5. For the inevitable blockage problem of similar products when measuring dirty media, there are online pull-out models or manual and automatic blowing solutions and devices available to achieve non-stop maintenance.

6. The integrated structure consists of an averaging tube, three valve group, temperature and pressure compensation, and transmitter, making it easy to use.

7. No flow coefficient drift, * stable.

8. Provide intuitive resonance verification to ensure stable operation.

9. Low pressure loss, low energy consumption, energy-saving *.

structural form
The averaging tube is composed of a detection rod, a pressure tap, and a guide rod. It crosses the interior of the pipeline perpendicular to the pipe axis. There are multiple total pressure detection holes on the upstream surface of the detection rod, which are respectively led out by the total pressure guide tube and the static pressure guide tube. Based on the differential pressure value between the total pressure and the static pressure, the flow rate through the pipeline is calculated. The cross-sectional shape of the detection rod is shown in the following figure:

theoretical basis

The averaging tube flowmeter is developed based on the principle of pitot tube velocity measurement. It determines the flow rate by multiplying the average flow velocity of the pipeline with the effective cross-sectional area of the pipeline.

Its flow calculation formula is:

Installation requirements
1. The measuring section for installing the detection rod should be straight, and the length of the upstream and downstream straight pipe sections should refer to the length specified in the table below.

Note: * D is the nominal diameter of the pipeline, and the given data is the length from the second bend.

2. The allowable deviation range for the angle of the detection rod insertion position is shown in Figure 5.

3. For vertical pipelines, the detection rod can be installed at any position along the circumference of the pipeline at 360 ° in the horizontal plane, and the high and low pressure impulse pipe joints should be on the same horizontal plane. For horizontal pipelines, the insertion position of the detection rod when measuring liquids should be within a range of 45 ° or less from the centerline of the horizontal plane of the pipeline cross-section; When measuring gas, the insertion position of the detection rod should be within a range of 45 ° or more from the centerline of the horizontal plane of the pipeline cross-section; When measuring steam, the detection rod should be inserted horizontally, as shown in Figure 6:

4. The opening size on the pipeline is Φ 40.

5. The compensating pressure transmitter is installed on the front straight pipe section, and the temperature transmitter (or platinum resistor) is installed on the rear straight pipe section at a distance of 2D from the throttling device.