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LF-19Q Venturi Flow Meter
● Minimal pressure loss and excellent energy efficiency: The unique "contraction-throat-expansion" structure recovers approximately 90% of the static pressure energy.
● Anti-clogging and wear-resistant with strong adaptability: The inner wall features a smooth surface free of sharp edges or constricted dead zones, making it highly resistant to impurity buildup (such as particles in wastewater or deposits in steam). This design ensures stable performance even under challenging conditions, including liquids containing minor impurities, high-temperature gases like steam, and corrosive media such as chemical solutions.
● Stable measurement with reliable accuracy: Measurement accuracy typically ranges from ±1% to ±2.5% of full scale (FS), and is minimally affected by fluctuations in fluid flow velocity or changes in medium viscosity. It ensures consistent, stable readings across a wide range of flow rates—from small to large (pipe diameters DN50 to DN2000).
● Flexible installation requirements: Only a straight pipe section of 5–10 times the pipe diameter upstream and 3–5 times downstream is needed—significantly less than the requirement for turbine flowmeters (10D upstream, 5D downstream)—making it more adaptable to limited installation spaces, especially ideal for scenarios with compact pipe layouts.
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Product Description
Product Overview Product overview
The LF-19Q Venturi flowmeter is a differential-pressure-type flow measurement instrument designed based on Bernoulli’s equation and the principle of fluid continuity. Its core structure consists of three main sections: an inlet contraction section, a central throat, and an outlet diffusion section. Thanks to its simple design and low energy consumption, it is widely used in industrial fluid measurement applications.
Performance metrics TECHNICAL PARAMETERS
| Tested medium |
Medium- to high-flow-rate media such as steam, compressed air, coal gas, and liquids |
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| Implementation Standards |
Vortex Shedding Flow Sensor (JB/T9249-2015) |
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| Verification Procedure |
Vortex Flow Meter (JG1029-2007) |
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| Instrument diameter (mm) and connection method
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Flange-connected type |
DN15-DN300 |
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| Clip-on Connection Type |
DN15-DN300 |
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| Accuracy Level |
Liquid: ±1%; Gas or vapor: ±1.5%, ±1% |
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| Measurement range ratio |
1:10; 1:15; 1:20 |
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| Sensor material |
304 stainless steel, 316 stainless steel, and more |
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| Terms of Use |
Media temperatures: -40°C to +70°C, -40°C to +250°C, -40°C to +350°C Ambient temperature: -20°C to +60°C Relative humidity: 5%–90% Atmospheric pressure: 86 kPa to 106 kPa |
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| Signal output function |
Pulse signals, 4–20mA signals |
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| Communication Output Function |
RS485 communication, HART protocol, and more |
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| Working power |
A. External Power Supply: +24VDC ±15%, Ripple ≤ ±5%, suitable for 4-20mA output, pulse output, RS485, and more B. Internal Power Supply: 1 set of 3.0V, 10Ah lithium batteries, which can operate normally when the battery voltage ranges from 2.0V to 3.0V. |
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| Flange Standards |
Standard specifications |
GB/T 9113-2000 |
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| Other standards |
International Pipe Flanges |
For example: German standard DIN, American standard ANSI, Japanese standard JIS |
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| Domestic Pipe Flanges |
For example: Standards of the Ministry of Chemical Industry, Standards of the Ministry of Machinery |
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| Electrical interface |
M20×1.5 internal thread (NPT threads require customization) |
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| Explosion-proof rating |
ExdIICT6 Gb |
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| Protection Level |
IP65 or higher (customizable) |
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How it works Working Principle
When a fluid—whether liquid or gas—flows through a converging section, its velocity gradually increases while its static pressure decreases. By the time the flow reaches the throat, the velocity hits its maximum, and the static pressure drops to its lowest point. Afterward, as the fluid enters the diverging section, the velocity slowly declines, and the static pressure partially recovers. By measuring the pressure difference between the "converging section and the throat," combined with parameters such as fluid density and pipe diameter, it’s possible to accurately calculate the actual flow rate.
External dimensions APPEARANCE OF SIZE
| Flange Connection Type Dimension Chart | |||||||||
| Instrument diameter (mm) |
L (mm) |
D (mm) |
K (mm) |
H(mm) | d (mm) |
n (Number of holes) |
Bolt specifications | Standard configuration Pressure-resistant |
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| Pulse Output Type | Smart-type | ||||||||
| 15 | 180 | 95 | 65 | 415 | 440 | 14 | 4 | M12×60 | Φ18 × 1.5 |
| 20 | 180 | 105 | 75 | 420 | 445 | 14 | 4 | M12×60 | Φ25 × 2.5 |
| 25 | 180 | 115 | 85 | 425 | 450 | 14 | 4 | M12×60 | Φ32 × 3.5 |
| 32 | 180 | 140 | 100 | 435 | 460 | 18 | 4 | M16×70 | Φ39 × 3.5 |
| 40 | 180 | 150 | 110 | 435 | 455 | 18 | 4 | M16×70 | Φ48×4 |
| 50 | 180 | 165 | 125 | 460 | 480 | 18 | 4 | M16×70 | Φ59 × 4.5 |
| 65 | 200 | 185 | 145 | 470 | 500 | 18 | 4 | M16×70 | Φ74 × 4.5 |
| 80 | 200 | 200 | 160 | 490 | 520 | 18 | 8 | M16×70 | Φ89 × 4.5 |
| 100 | 200 | 220 | 180 | 515 | 545 | 18 | 8 | M16×70 | Φ109 × 4.5 |
| 125 | 220 | 250 | 210 | 535 | 560 | 18 | 8 | M16×70 | Φ134 × 4.5 |
| 150 | 220 | 285 | 240 | 570 | 595 | 22 | 8 | M16 × 90 | Φ159 × 4.5 |
| 200 | 220 | 340 | 295 | 625 | 650 | 22 | 12 | M16 × 90 | Φ219 × 9 |
| 250 | 250 | 405 | 355 | 685 | 710 | 26 | 12 | M24×110 | Φ273 × 11 |
| 300 | 300 | 460 | 410 | 710 | 735 | 26 | 12 | M24×110 | Φ325 × 12 |
Note: ① All the above parameters apply to vortex flowmeters with a flanged connection and a pressure rating of 1.6 MPa.
② The flanged vortex flowmeter is delivered from the factory without pipe flanges and bolts, which must be purchased separately by the user. The standard for the connecting flange is GB/T 9113-2000 Raised Face Flat-Welded Steel Pipe Flange.
Installation Requirements INSTALLATION
1. Cut an opening in the pipe according to the required opening dimensions, ensuring that the opening aligns with the straight pipe section requirements.
2. Place the complete flowmeter assembly, with the flange already connected, into the pipe that has been opened.
3. Spot-weld the flange to the pipe for positioning.
4. Remove the flowmeter, weld the flanges according to specifications, and carefully clean all protruding parts inside the pipeline. Install a sealing gasket of the same diameter as the pipe into the inner groove of the flange, then insert the flowmeter into the flange assembly—with the flowmeter’s directional arrow aligned in the same direction as the fluid flow—and finally secure it tightly using the bolts.
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