The Annubar Flow Meter is an insertion-type flow sensor used to measure the flow of liquids, gases, and steam in oil refining, chemical, metal sheet manufacturing, medicine, and other industrial fields. When used together with display meters, it can accurately measure all flowing substances in ducts or pipes from DN25 to DN4000 mm. It is also suitable for high temperature, high pressure environments, and heavily polluted liquids.
Key benefits: novel design, no special requirements on upstream and downstream straight pipes, easy installation and repair, accurate measurement, small pressure loss, stable long-term operation, and energy-saving.
Simple insertion structure — no crane needed for installation, few welding seams, saves time and installation cost
Short straight pipe requirements — only ≥2D upstream and 2D downstream, making it easy to design and install
Energy saving — pressure loss is only 2–10% of differential pressure, significantly reducing energy consumption
Easy maintenance — designed based on physical principles so solids and suspension do not easily accumulate on the sensing surface; if blocked, cleaning can be done by iron wire, reverse-flow purging, or removing the wet rod; no easily worn parts, virtually maintenance-free
Constant flow coefficient — remains stable even after long-term use
Specifications
Pipeline Diameter
DN25 – DN4000 mm
Reynolds Number Range
3 × 10³ – 1 × 10⁷
Nominal Pressure
≤ 12 MPa
Measurement Range Ratio
≤ 3:1
Medium Viscosity
≤ 0.3 Pa·s
Medium Temperature
≤ 500°C
Accuracy
±1% (precision Grade A)
Repeatability
±0.1%
Stability
±0.5%
Pressure Loss
Only 2–10% of differential pressure (energy saving)
Installation Angle
0–360° on pipeline
Upstream Straight Run
≥ 2D
Downstream Straight Run
2D
Working Principle
The Annubar flowmeter adopts a rhombic (diamond) cross-section sensing rod to effectively control the boundary layer separation points. This makes it independent of Reynolds number effects and produces a constant flow coefficient, increasing measurement precision.
The flowmeter consists of five basic parts:
Static pressure lead-out tube — brings the static pressure from the rear sensing hole to the negative pressure side of the differential pressure transmitter
Interpolating tube — brings the total pressure instantaneously measured by four upstream-facing holes to the positive pressure side of the differential pressure transmitter
Static pressure hole — placed in the center of the flow element facing downstream, for measuring static pressure
Wet rod (sensing rod) — the complete sensing element containing four total pressure holes, one static pressure hole, an interpolating tube, and a static pressure lead-out tube
Total pressure holes — four measuring holes designed according to the Tchebycheff formula, located on four equal annuli (two semi-rings, two semi-circles), facing upstream to measure the total pressure at each standard point
Order Guide
In addition to regular products, we support customization
ANR-71
Flange pipeline flowmeter
DN25 – DN80
0 – 500°C
4 MPa
ANR-72
Common pipeline flowmeter
DN25 – DN80
0 – 500°C
4 MPa
ANR-73
Narrow pipeline flowmeter
DN50 – DN150
0 – 500°C
2.5 MPa
ATM-74
Low pressure non-stop working flowmeter
DN100 – DN500
0 – 500°C
2.5 MPa
ATM-73
Shake-resistant low pressure non-stop working flowmeter
DN500 – DN2000
0 – 500°C
2.5 MPa
ANR-75
Common flowmeter (standard)
DN100 – DN500
0 – 500°C
2.5 MPa
ANR-76
Shake-resistant common flowmeter
DN300 – DN4000
0 – 500°C
2.5 MPa
ANR-75 (HP)
High pressure flange flowmeter
DN100 – DN500
0 – 500°C
12 MPa
ANF-76
Shake-resistant flange flowmeter
DN200 – DN4000
0 – 500°C
12 MPa
ATM-75
Non-stop flow working flowmeter
DN100 – DN500
0 – 500°C
6.4 MPa
ATM-76
Shake-resistant non-stop working flowmeter
DN300 – DN2000
0 – 500°C
6.4 MPa
Measuring System Components
A complete Annubar flow measurement system consists of:
Annubar flowmeter (sensor)
Differential pressure transmitter (outputs 0–10 mA or 4–20 mA current signal)
Totalizer (square root extractor)
Indicator or recorder
Applications
Gas delivery and liquid delivery
Energy research, steam boiler heat rate, pump efficiency.
Gas compressor efficiency and fuel consumption
Process control: input and output, ratio, balance; cooling water or air, steam heating.
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Zhang Wei, possesses 20 years of experience as an automation instrumentation engineer, specializing in the research, design, installation, commissioning, and maintenance of automation instruments.
Face to various instrument communication protocols (such as Modbus, Profibus, etc.), with solid hardware circuit design and software programming skills (proficient in C language and PLC programming). Has extensive project experience; projects he has led and participated in have all achieved outstanding results, improving product accuracy, reducing costs, and increasing production efficiency.
Possesses excellent communication and coordination skills and a strong team spirit, enabling him to quickly respond to customer needs and provide high-quality automation instrumentation solutions.
