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LF-19F Series Orifice Flow Meters
● The structure is easy to replicate, simple yet sturdy, with stable and reliable performance, and at an affordable price.
● Widely applicable, covering single-phase fluids (liquid, gas, steam), as well as partially miscible flows. Products are available for pipe diameters and operating conditions—such as temperature and pressure—commonly encountered in industrial processes. Moreover, throttling devices, differential pressure transmitters, and display instruments can be manufactured separately by different suppliers, making it easier to achieve large-scale production.
●The annular chamber and drilled holes enhance measurement accuracy while reducing the minimum required straight pipe length for installation.
● In addition to its online, dynamic full-compensation function, the intelligent orifice flowmeter also features self-diagnosis and automatic range setting.
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Product Description
Product Overview Product overview
The LF-19F series orifice plate flowmeter is a typical differential-pressure flowmeter, designed for use in conjunction with transmitters and display units (or indicating instruments). It enables precise measurement of fluid flow rates and is widely adopted across various industrial sectors due to its simple design, convenient installation, and reliable operational performance. Orifice plate flowmeters boast a long history of practical application, supported by extensive experimental data. Their design and manufacturing processes have been standardized, eliminating the need for actual-flow calibration. Moreover, these devices can handle a wide variety of media types, accommodate diverse pipe diameters, and operate effectively over an impressive temperature range—up to 550°C—and withstand pressures as high as 32 MPa. As a result, they remain one of the primary instruments used for accurate flow measurement in industrial automation and control systems.
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 between 2.0V and 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
The vortex shedding flowmeter consists of a vortex generator, a detection probe, and the corresponding electronic circuitry. When a fluid flows past the vortex generator, it creates two alternating rows of vortices on either side—these vortices are known as Karman vortices. Building on Karman's vortex street theory, Strouhal further proposed that the frequency of the Karman vortex street is directly proportional to the fluid's flow velocity, and he provided the following equation relating frequency to flow speed:
f = St × V/d where:
f: Vortex shedding frequency (Hz)
V: Average flow velocity (m/s) on both sides of the vortex generator
St: Strouhal number (constant within a certain range of Reynolds numbers)
d: Width of the vortex generator's upstream face (m)
These alternating vortices generate a series of fluctuating fluid lift forces, which act on the piezoelectric-based sensing probe, producing a corresponding series of alternating electrical charge signals. After being processed by a pre-amplifier—where they undergo conversion, shaping, and amplification—the signals are finally output as pulse signals that match the vortex shedding frequency and are directly proportional to the flow velocity.
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 pressure rating of 1.6 MPa and flanged connections.
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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