Flow Control
Explore our comprehensive range of Flow Control products, featuring precision instruments such as flow meters, flow switches, flow transmitters, and flow sensors. Our offerings cater to diverse applications, ensuri...
Categories in Flow Control Products (6)
Flow Meters
Flow meters are a piece of essential equipment for many industries, as they allow for accurately measuring fluid flow rates. At Centro, we carry a complete online selection of flow meters, including magnetic flow meters, turbine flow meters, and positive displacement flow meters. We also offer a variety of accessories and replacement parts to ensure that your flow meter always operates at peak efficiency. Whether you're looking for a new flow meter or need to restock your supplies, Centro has everything you need to keep your operation running smoothly.
Flow Switches
Flow switches are vital instruments in fluid systems that detect the presence or absence of flow. These devices ensure proper operation and prevent issues such as pump damage or system failure. Flow switches are employed in various industries to monitor and control the flow of liquids or gases, providing a reliable means of safeguarding equipment and optimizing fluid processes.
Flow Transmitters
Flow Transmitters are essential in fluid systems, accurately measuring and transmitting flow rate data. These devices play a critical role in monitoring and controlling the flow of liquids or gases in various applications. By providing real-time information, Flow Transmitters enable precise adjustments, ensuring optimal performance and efficiency. Their reliability and accuracy make them indispensable for industries where precise flow measurement is crucial.
Flow Sensors
Flow Sensors are key elements in fluid systems, detecting and measuring the flow rate. These devices offer real-time data on liquid or gas movement, enabling precise control and monitoring. Flow Sensors are essential in manufacturing, healthcare, and environmental monitoring industries, providing valuable insights for process optimization, quality control, and regulatory compliance.
Flow, pH & Conductivity Meters, Transmitters & Controllers
Centro offers a wide range of flow, pH, and conductivity meters, transmitters, and controllers to meet the demands of various industrial and commercial applications. From monitoring flow rates and maintaining chemical balance for fluid quality and consistency, our solutions are engineered for precision, reliability, and seamless integration. We provide products such as magnetic and ultrasonic flow meters, pH controllers, and conductivity transmitters designed to optimize performance in industries like water treatment, food and beverage, chemical processing, and pharmaceuticals.
Whether you need accurate measurements, durable equipment, or easy system integration, Centro has the expertise and products to support your operations. Explore our selection online or contact our team to find the right solution for your application and ensure peak system efficiency.
Flow Control Accessories
Flow Control Accessories encompass a range of supplementary components designed to optimize, support, or enhance the operation of primary flow control equipment such as valves, regulators, actuators, and pumps. These accessories are critical in ensuring precise control, safety, and efficiency within fluid and gas systems across industrial, commercial, and residential applications.
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The Dwyer - FMA1002R-MA is an Air Velocity/Temperature Transmitter featuring 15 Vdc to 24 Vdc, 0 FPM to 5000 FPM, ± 1.5 % Accuracy, 4 mA to 20 mA, 1/4 " x 12 " (DxL), and Remote Mount Probe. Part of the FMA1000 Series. Sold individually.
$1,432.85$1,554.13
Should ship between 08 Dec and 15 Dec
Subject to factory lead times
The Dwyer - FMA1003R-MA-S is an Air Velocity/Temperature Transmitter featuring 15 Vdc to 24 Vdc, 0 FPM to 10000 FPM, ± 1.5 % Accuracy, 4 mA to 20 mA, 1/4 " x 3-3/4 " (DxL), and Remote Mount Probe. Part of the FMA1000 Series. Sold individually.
$1,400.27$1,518.79
Should ship between 08 Dec and 15 Dec
Subject to factory lead times
The Dwyer - FMA1720A is a Mass Flow Meter featuring Economical, Gas, 0.1 SLM to 10 SLM, 1000 psi, 1/4 " Compression, 0 Vdc to 5 Vdc, 4 mA to 20 mA, ± 1 %, Al, Brass, and FKM. It is rated for a temperature range of 50 °C (122 °F). Part of the FMA1700A Series. Sold individually.
$879.97
Should ship between 01 Dec and 15 Dec
Subject to factory lead times
The Dwyer - FMA5523A is a Mass Flow Controller featuring Economical, Gas, 0.375 SLM to 15 SLM, 1000 psi, ± 1 %, 1/4 " Compression, 0 Vdc to 5 Vdc, 4 mA to 20 mA, Std, LCD, Al, Brass, and FKM. It is rated for a temperature range of 50 °C (122 °F). Part of the FMA5500A Series. Sold individually.
$1,942.84
Should ship between 01 Dec and 15 Dec
Subject to factory lead times
The Dwyer - FMA5542A is a Mass Flow Controller featuring Economical, Gas, 2.5 SLM to 100 SLM, 500 psi, ± 1.5 %, 3/8 " Compression, 0 Vdc to 5 Vdc, 4 mA to 20 mA, Std, LCD, Al, Brass, and FKM. It is rated for a temperature range of 50 °C (122 °F). Part of the FMA5500A Series. Sold individually.
$2,013.71
Should ship between 01 Dec and 15 Dec
Subject to factory lead times
The Dwyer - FMA904A-V1 is an Air Velocity Transmitter featuring Hot Wire, 15 Vdc to 24 Vdc, 0 FPM to 5000 FPM, ± 15 FPM Accuracy, 0 Vdc to 5 Vdc, 1/4 " x 12 " (DxL), Fixed Probe, and SPST Relay. Part of the FMA904A Series. Sold individually.
$670.80$727.57
Should ship between 08 Dec and 15 Dec
Subject to factory lead times
The Dwyer - FMG3002-PP-D is an Electromagnetic Flow Meter with LCD Display featuring Conductive Fluids, 0.15 FPS to 16.4 FPS, 1/2 " to 4 ", FP-5300 Sensor Installation, ± 1 %, 4 mA to 20 mA, 316 SS, PP, and FKM. Part of the FMG3000 Series. Sold individually.
$2,731.64
Should ship between 15 Dec and 22 Dec
Subject to factory lead times
The Dwyer - FP-5301 is a Paddlewheel Flow Sensor featuring Low Cost, 1 FPS to 20 FPS, ± 1 % Accuracy, Sinusoidal, PP, 180 psi, and 5 " to 8 " Pipe. Part of the FP-5300 Series. Sold individually.
$553.49
Should ship between 01 Dec and 15 Dec
Subject to factory lead times
The Dwyer - FP7001A is a Flow Sensor featuring Fixed Length Insertion Paddlewheel, 5 Vdc to 18 Vdc, 2 GPM to 460 GPM, ± 2 % Accuracy, Amplified Square Pulse, PP, and 150 psi. Sold individually.
$456.37$494.99
Should ship between 24 Nov and 01 Dec
Subject to factory lead times
The Dwyer - FPD3303 is a Positive Displacement Flow Meter for Solvents featuring 4.5 Vdc to 24 Vdc, 4 GPH to 132 GPH, 1/4 ", NPT Female, ± 0.5 %, Amplified Square Wave, SS, and FEP. Part of the FPD3300 Series. Sold individually.
$1,481.30
Should ship between 01 Dec and 15 Dec
Subject to factory lead times
The Dwyer - FPM-5750-P is a Battery Powered Flow Indicator & Totalizer featuring Frequency, 1-Input, Panel Mount, 0 Hz to 400 Hz, and LCD Display. Part of the FPM-5750 Series. Sold individually.
$908.07
Should ship between 15 Dec and 22 Dec
Subject to factory lead times
The Dwyer - FSW-43A is a Flow Switch for 10 " to 48 " Pipe featuring Industrial, Liquid, 2 FPS to 15 FPS, 15 A SPDT, 1 ", NPT Male, Brass, 316 SS, Phosphor Bronze, and EPDM. Part of the FSW-40A Series. Sold individually.
$745.16
Should ship between 24 Nov and 01 Dec
Subject to factory lead times
The Dwyer - FT-250806-S is an Adaptor featuring Barbed-Stem, Straight, Acetal, 1/4 " (OD), and 3/16 " (ID). Part of the FT Series. Sold individually.
$78.98
Should ship between 02 Feb and 09 Feb
Subject to factory lead times
The Dwyer - FT-PLC220-04 is a Quick Coupling Insert featuring Plug, Barbed, Straight, Acetal, 1/4 " (ID), and Straight Thru. Part of the FT-PLC Series. Sold individually.
$6.90
Should ship between 08 Dec and 15 Dec
Subject to factory lead times
The Dwyer - FT-PLC220-04-12 is a Quick Coupling Insert featuring Plug, Barbed, Straight, Polypropylene, 1/4 " (ID), Straight Thru, and Length 1.35 ". Part of the FT-PLC-12 Series. Sold individually.
$9.04
Should ship between 08 Dec and 15 Dec
Subject to factory lead times
The Dwyer - FT-PLCD100-04-12 is a Plastic Quick Coupling Body featuring Socket, Threaded, 1/4 " NPT Male, Straight, Polypropylene, Shutoff, and Length 1.15 ". Part of the FT-PLC-12 Series. Sold individually.
$33.47
Should ship between 08 Dec and 15 Dec
Subject to factory lead times
The Dwyer - FT-TFF-01 is a Multitube Quick Fitting Body featuring Socket, Push to Connect, Straight, Acetal, 1/16 " (ID), and Straight Thru. Part of the FT-TF Series. Sold individually.
$6.89
Should ship between 08 Dec and 15 Dec
Subject to factory lead times
The Dwyer - FT-TMF-01 is a Multitube Quick Fitting Insert featuring Plug, Push to Connect, Straight, Acetal, 1/16 " (ID), and Straight Thru. Part of the FT-TMF Series. Sold individually.
$9.00
Should ship between 08 Dec and 15 Dec
Subject to factory lead times
The Dwyer - FTB311 is a Micro Flow Meter featuring Low Flow Indicating, 9 Vdc to 28 Vdc, 30 ml/min to 300 ml/min, 1/8 ", NPT Female, ± 6 % Accuracy, Amplified Square Pulse, PVDF, and 130 psi. Part of the FTB300 Series. Sold individually.
$348.83
Should ship between 17 Nov and 24 Nov
Subject to factory lead times
The Dwyer - FTPP-A6-8NP is an Adaptor featuring Threaded-Barbed, 3/8 " NPT Male, Straight, Polypropylene, and 1/2 " (ID). Part of the FTPP Series. Sold as a pack of 10.
$14.56
Should ship between 24 Nov and 01 Dec
Subject to factory lead times
The Dwyer - FV106 is a Vortex Shedding Flow Meter featuring 20 GPM to 200 GPM, 2 " NPT Female, ± 2 %, 10 Vdc to 30 Vdc, 4 mA to 20 mA, 125 mA SPST SSR, Brass, PVDF, FKM O-RING, and LCD Display. Part of the FV101 Series. Sold individually.
$1,702.64
Should ship between 12 Jan and 19 Jan
Subject to factory lead times
The Dwyer - G2S10TQ9GMV is a Turbine Flow Meters: Sensor with Display featuring 1" TURBINE, TOTAL, and RATE 50GPM. Sold individually.
$1,349.61
Should ship between 17 Nov and 24 Nov
Subject to factory lead times
Configure product to see pricing
The TKB Series battery operated in-line plastic paddle wheel flow meter sensor has been designed for tough industrial applications. The TKB series paddle wheel flow meter sensor has been engineered to provide long-term accurate flow measurement for both corrosive and non-corrosive liquids. The all plastic in-line digital flow meter sensor is equipped with a 360° rotatable vivid backlit LCD display showing both Flow Rate & Flow Total. The re-engineered low-drag, fluid-dynamic design of the paddle wheel allows it to stand alone as the industry’s most accurate flow meter sensor.
The TKB series plastic flow meter sensors incorporate an all new re-designed air-foil designed rotor that reduces turbulence and drag as the liquid passes by up to 92%. The zirconium rotor pin has been polished to a mirror finish and provides superior chemical and wear resistance over a metal pin. It should be noted that the rotor has been outfitted with two (2) ceramic bushings. This allows for much finer rotor pin to paddle alignment and greatly reduces paddle wobble that occurs without bushings. Icon’s liquid flow meters incorporate a Tefzel® paddle coupled with a zirconium ceramic rotor pin and bushings. The TKB series battery operated liquid flow meter is industry’s longest lasting paddle wheel flow meter and comes with a lifetime warranty on the paddle wheel assembly.
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The TKP Series digital in-line paddle wheel flow meter sensor has been designed for tough industrial applications. The TKP series paddle wheel flow meter sensor has been engineered to provide long-term accurate flow measurement for both corrosive and non-corrosive liquids. The plastic in-line flow meter sensor is equipped with a 360° rotatable vivid LED display showing both Flow Rate & Flow Total and provides a frequency pulse output. The re-engineered low-drag, fluid-dynamic design of the paddle wheel allows it to stand alone as the industry’s most accurate flow meter sensor.
The TKP series plastic flow meter sensors incorporate an all new re-designed air-foil designed rotor that reduces turbulence and drag as the liquid passes by up to 92%. The zirconium rotor pin has been polished to a mirror finish and provides superior chemical and wear resistance over a metal pin. It should be noted that the rotor has been outfitted with two (2) ceramic bushings. This allows for much finer rotor pin to paddle alignment and greatly reduces paddle wobble that occurs without bushings. Icon’s liquid flow meters incorporate a Tefzel® paddle coupled with a zirconium ceramic rotor pin and bushings. The TKP series liquid flow meter is industry’s longest lasting paddle wheel flow meter and comes with a lifetime warranty on the paddle wheel assembly.
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The Dwyer - FMA1002R-MA is an Air Velocity/Temperature Transmitter featuring 15 Vdc to 24 Vdc, 0 FPM to 5000 FPM, ± 1.5 % Accuracy, 4 mA to 20 mA, 1/4 " x 12 " (DxL), and Remote Mount Probe. Part of the FMA1000 Series. Sold individually.
$1,432.85$1,554.13
Should ship between 08 Dec and 15 Dec
Subject to factory lead times
The Dwyer - FMA1003R-MA-S is an Air Velocity/Temperature Transmitter featuring 15 Vdc to 24 Vdc, 0 FPM to 10000 FPM, ± 1.5 % Accuracy, 4 mA to 20 mA, 1/4 " x 3-3/4 " (DxL), and Remote Mount Probe. Part of the FMA1000 Series. Sold individually.
$1,400.27$1,518.79
Should ship between 08 Dec and 15 Dec
Subject to factory lead times
The Dwyer - FMA1720A is a Mass Flow Meter featuring Economical, Gas, 0.1 SLM to 10 SLM, 1000 psi, 1/4 " Compression, 0 Vdc to 5 Vdc, 4 mA to 20 mA, ± 1 %, Al, Brass, and FKM. It is rated for a temperature range of 50 °C (122 °F). Part of the FMA1700A Series. Sold individually.
$879.97
Should ship between 01 Dec and 15 Dec
Subject to factory lead times
The Dwyer - FMA5523A is a Mass Flow Controller featuring Economical, Gas, 0.375 SLM to 15 SLM, 1000 psi, ± 1 %, 1/4 " Compression, 0 Vdc to 5 Vdc, 4 mA to 20 mA, Std, LCD, Al, Brass, and FKM. It is rated for a temperature range of 50 °C (122 °F). Part of the FMA5500A Series. Sold individually.
$1,942.84
Should ship between 01 Dec and 15 Dec
Subject to factory lead times
The Dwyer - FMA5542A is a Mass Flow Controller featuring Economical, Gas, 2.5 SLM to 100 SLM, 500 psi, ± 1.5 %, 3/8 " Compression, 0 Vdc to 5 Vdc, 4 mA to 20 mA, Std, LCD, Al, Brass, and FKM. It is rated for a temperature range of 50 °C (122 °F). Part of the FMA5500A Series. Sold individually.
$2,013.71
Should ship between 01 Dec and 15 Dec
Subject to factory lead times
The Dwyer - FMA904A-V1 is an Air Velocity Transmitter featuring Hot Wire, 15 Vdc to 24 Vdc, 0 FPM to 5000 FPM, ± 15 FPM Accuracy, 0 Vdc to 5 Vdc, 1/4 " x 12 " (DxL), Fixed Probe, and SPST Relay. Part of the FMA904A Series. Sold individually.
$670.80$727.57
Should ship between 08 Dec and 15 Dec
Subject to factory lead times
The Dwyer - FMG3002-PP-D is an Electromagnetic Flow Meter with LCD Display featuring Conductive Fluids, 0.15 FPS to 16.4 FPS, 1/2 " to 4 ", FP-5300 Sensor Installation, ± 1 %, 4 mA to 20 mA, 316 SS, PP, and FKM. Part of the FMG3000 Series. Sold individually.
$2,731.64
Should ship between 15 Dec and 22 Dec
Subject to factory lead times
The Dwyer - FP-5301 is a Paddlewheel Flow Sensor featuring Low Cost, 1 FPS to 20 FPS, ± 1 % Accuracy, Sinusoidal, PP, 180 psi, and 5 " to 8 " Pipe. Part of the FP-5300 Series. Sold individually.
$553.49
Should ship between 01 Dec and 15 Dec
Subject to factory lead times
The Dwyer - FP7001A is a Flow Sensor featuring Fixed Length Insertion Paddlewheel, 5 Vdc to 18 Vdc, 2 GPM to 460 GPM, ± 2 % Accuracy, Amplified Square Pulse, PP, and 150 psi. Sold individually.
$456.37$494.99
Should ship between 24 Nov and 01 Dec
Subject to factory lead times
The Dwyer - FPD3303 is a Positive Displacement Flow Meter for Solvents featuring 4.5 Vdc to 24 Vdc, 4 GPH to 132 GPH, 1/4 ", NPT Female, ± 0.5 %, Amplified Square Wave, SS, and FEP. Part of the FPD3300 Series. Sold individually.
$1,481.30
Should ship between 01 Dec and 15 Dec
Subject to factory lead times
The Dwyer - FPM-5750-P is a Battery Powered Flow Indicator & Totalizer featuring Frequency, 1-Input, Panel Mount, 0 Hz to 400 Hz, and LCD Display. Part of the FPM-5750 Series. Sold individually.
$908.07
Should ship between 15 Dec and 22 Dec
Subject to factory lead times
The Dwyer - FSW-43A is a Flow Switch for 10 " to 48 " Pipe featuring Industrial, Liquid, 2 FPS to 15 FPS, 15 A SPDT, 1 ", NPT Male, Brass, 316 SS, Phosphor Bronze, and EPDM. Part of the FSW-40A Series. Sold individually.
$745.16
Should ship between 24 Nov and 01 Dec
Subject to factory lead times
The Dwyer - FT-250806-S is an Adaptor featuring Barbed-Stem, Straight, Acetal, 1/4 " (OD), and 3/16 " (ID). Part of the FT Series. Sold individually.
$78.98
Should ship between 02 Feb and 09 Feb
Subject to factory lead times
The Dwyer - FT-PLC220-04 is a Quick Coupling Insert featuring Plug, Barbed, Straight, Acetal, 1/4 " (ID), and Straight Thru. Part of the FT-PLC Series. Sold individually.
$6.90
Should ship between 08 Dec and 15 Dec
Subject to factory lead times
The Dwyer - FT-PLC220-04-12 is a Quick Coupling Insert featuring Plug, Barbed, Straight, Polypropylene, 1/4 " (ID), Straight Thru, and Length 1.35 ". Part of the FT-PLC-12 Series. Sold individually.
$9.04
Should ship between 08 Dec and 15 Dec
Subject to factory lead times
The Dwyer - FT-PLCD100-04-12 is a Plastic Quick Coupling Body featuring Socket, Threaded, 1/4 " NPT Male, Straight, Polypropylene, Shutoff, and Length 1.15 ". Part of the FT-PLC-12 Series. Sold individually.
$33.47
Should ship between 08 Dec and 15 Dec
Subject to factory lead times
The Dwyer - FT-TFF-01 is a Multitube Quick Fitting Body featuring Socket, Push to Connect, Straight, Acetal, 1/16 " (ID), and Straight Thru. Part of the FT-TF Series. Sold individually.
$6.89
Should ship between 08 Dec and 15 Dec
Subject to factory lead times
The Dwyer - FT-TMF-01 is a Multitube Quick Fitting Insert featuring Plug, Push to Connect, Straight, Acetal, 1/16 " (ID), and Straight Thru. Part of the FT-TMF Series. Sold individually.
$9.00
Should ship between 08 Dec and 15 Dec
Subject to factory lead times
The Dwyer - FTB311 is a Micro Flow Meter featuring Low Flow Indicating, 9 Vdc to 28 Vdc, 30 ml/min to 300 ml/min, 1/8 ", NPT Female, ± 6 % Accuracy, Amplified Square Pulse, PVDF, and 130 psi. Part of the FTB300 Series. Sold individually.
$348.83
Should ship between 17 Nov and 24 Nov
Subject to factory lead times
The Dwyer - FTPP-A6-8NP is an Adaptor featuring Threaded-Barbed, 3/8 " NPT Male, Straight, Polypropylene, and 1/2 " (ID). Part of the FTPP Series. Sold as a pack of 10.
$14.56
Should ship between 24 Nov and 01 Dec
Subject to factory lead times
The Dwyer - FV106 is a Vortex Shedding Flow Meter featuring 20 GPM to 200 GPM, 2 " NPT Female, ± 2 %, 10 Vdc to 30 Vdc, 4 mA to 20 mA, 125 mA SPST SSR, Brass, PVDF, FKM O-RING, and LCD Display. Part of the FV101 Series. Sold individually.
$1,702.64
Should ship between 12 Jan and 19 Jan
Subject to factory lead times
The Dwyer - G2S10TQ9GMV is a Turbine Flow Meters: Sensor with Display featuring 1" TURBINE, TOTAL, and RATE 50GPM. Sold individually.
$1,349.61
Should ship between 17 Nov and 24 Nov
Subject to factory lead times
Configure product to see pricing
The TKB Series battery operated in-line plastic paddle wheel flow meter sensor has been designed for tough industrial applications. The TKB series paddle wheel flow meter sensor has been engineered to provide long-term accurate flow measurement for both corrosive and non-corrosive liquids. The all plastic in-line digital flow meter sensor is equipped with a 360° rotatable vivid backlit LCD display showing both Flow Rate & Flow Total. The re-engineered low-drag, fluid-dynamic design of the paddle wheel allows it to stand alone as the industry’s most accurate flow meter sensor.
The TKB series plastic flow meter sensors incorporate an all new re-designed air-foil designed rotor that reduces turbulence and drag as the liquid passes by up to 92%. The zirconium rotor pin has been polished to a mirror finish and provides superior chemical and wear resistance over a metal pin. It should be noted that the rotor has been outfitted with two (2) ceramic bushings. This allows for much finer rotor pin to paddle alignment and greatly reduces paddle wobble that occurs without bushings. Icon’s liquid flow meters incorporate a Tefzel® paddle coupled with a zirconium ceramic rotor pin and bushings. The TKB series battery operated liquid flow meter is industry’s longest lasting paddle wheel flow meter and comes with a lifetime warranty on the paddle wheel assembly.
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The TKP Series digital in-line paddle wheel flow meter sensor has been designed for tough industrial applications. The TKP series paddle wheel flow meter sensor has been engineered to provide long-term accurate flow measurement for both corrosive and non-corrosive liquids. The plastic in-line flow meter sensor is equipped with a 360° rotatable vivid LED display showing both Flow Rate & Flow Total and provides a frequency pulse output. The re-engineered low-drag, fluid-dynamic design of the paddle wheel allows it to stand alone as the industry’s most accurate flow meter sensor.
The TKP series plastic flow meter sensors incorporate an all new re-designed air-foil designed rotor that reduces turbulence and drag as the liquid passes by up to 92%. The zirconium rotor pin has been polished to a mirror finish and provides superior chemical and wear resistance over a metal pin. It should be noted that the rotor has been outfitted with two (2) ceramic bushings. This allows for much finer rotor pin to paddle alignment and greatly reduces paddle wobble that occurs without bushings. Icon’s liquid flow meters incorporate a Tefzel® paddle coupled with a zirconium ceramic rotor pin and bushings. The TKP series liquid flow meter is industry’s longest lasting paddle wheel flow meter and comes with a lifetime warranty on the paddle wheel assembly.
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FAQS
- Measuring flow rate in a pipe requires a flow meter matched to the fluid type, pipe size, flow range, and accuracy requirement. For conductive liquids (water, chemicals, slurries), magnetic flow meters are the most popular choice — they have no moving parts, create no pressure drop, and handle dirty or abrasive fluids. For non-conductive liquids or retrofit installations where you can't cut the pipe, clamp-on ultrasonic flow meters mount externally and measure through the pipe wall. For applications requiring the highest accuracy or mass flow measurement (batching, custody transfer), Coriolis meters measure mass flow directly. For steam and gas, vortex meters are robust and widely used. For simple, low-cost local visual indication of flow rate, variable-area meters (rotameters) provide a direct reading without power or electronics. Flow switches are used when you only need to confirm flow is present or absent — for example, verifying cooling water is running before allowing a machine to start. The flow meter output (typically 4–20 mA) feeds back to a PLC or controller for monitoring, totalization, or closed-loop flow control.
- The flow meter technology must match the fluid type, pipe size, accuracy requirement, and process conditions. Magnetic (mag) flow meters measure conductive liquids (water, chemicals, slurries) using Faraday's law — they have no moving parts, handle dirty or abrasive fluids well, and are the default for water and wastewater applications. Ultrasonic flow meters (transit-time and Doppler) are non-intrusive and can be clamp-on, ideal for retrofit or applications where the pipe cannot be cut. Coriolis meters measure mass flow directly with very high accuracy — the premium choice for custody transfer, batching, and applications requiring density measurement. Vortex meters are robust and versatile for steam, gas, and liquid measurement in moderate-to-large pipe sizes. Variable-area meters (rotameters) provide simple, low-cost local visual indication of flow rate. Turbine meters offer high accuracy for clean, low-viscosity liquids. The best approach is to define the fluid properties, flow range, accuracy requirement, and installation constraints, then match to the technology that fits.
- A flow switch detects whether flow is present or absent (or above/below a threshold) and outputs a discrete on/off signal — it does not measure the actual flow rate. Flow switches are used for protection and alarm functions: confirming cooling water is flowing before allowing a machine to operate, detecting loss of lubrication flow to trigger a shutdown, or verifying that a pump is actually moving fluid. They are simpler and less expensive than flow meters. A flow meter, by contrast, measures the actual flow rate (GPM, liters/minute, SCFM, etc.) and provides a continuous analog or digital output proportional to the flow value. Flow meters are used when the control system needs to know how much fluid is flowing — for batching, dosing, energy accounting, and closed-loop flow control. If you only need to know whether flow is on or off, a flow switch is sufficient. If you need to know how much, you need a flow meter.
- A magnetic flow meter (mag meter) uses Faraday's law of electromagnetic induction to measure the velocity of a conductive liquid flowing through a pipe. The meter generates a magnetic field across the pipe, and the flowing conductive liquid produces a voltage proportional to its velocity — this voltage is measured by electrodes in the pipe wall and converted to a flow rate. Mag meters have several significant advantages: no moving parts (zero maintenance on the sensor itself), no obstruction to flow (full bore, no pressure drop), excellent performance with dirty, abrasive, and slurry-containing liquids, wide turndown ratios (typically 100:1 or greater), and bidirectional measurement capability. They are the standard choice for water and wastewater treatment, chemical processing, food and beverage, pharmaceutical, and pulp and paper applications. The main limitation is that the liquid must be electrically conductive (minimum ~5 µS/cm) — mag meters cannot measure hydrocarbons, deionized water, or gases.
- Flow meter sizing must balance accuracy, rangeability, and pressure drop. The meter should be sized so that the normal operating flow rate falls within the meter's optimal accuracy range — typically between 25% and 75% of its full-scale capacity. Sizing based solely on the pipe diameter is a common mistake — if the pipe is oversized for the actual flow rate (which is common in many installations), the flow velocity through the meter will be too low for accurate measurement. In these cases, the meter should be sized smaller than the pipe, with reducers and expanders installed to transition from the pipe size to the meter size. Key data needed for sizing includes the fluid type and properties (density, viscosity, conductivity, temperature, pressure), the minimum, normal, and maximum flow rates, the required accuracy, and the acceptable pressure drop. Most flow meter manufacturers provide online sizing tools where you input these parameters and receive a recommended meter size and model.