A turbine flow meter is a volume flowmeter that uses the mechanical energy of the liquid or gas to rotate a rotor in the flow stream. The velocity of the turbine rotor is proportional to the velocity of the fluid passing through the flow meter. The frequency of the signal relates directly to flow rate.
Turbine flow meters measure the velocity of liquids, gases and vapors in pipes, including hydrocarbons, diesel, water, cryogenic liquids, air, and industrial gases. The turbine flow meter is one of the most widely used devices to measure flow electronically. They offer a wide flow and application rangeability, are easy to maintain, durable and versatile.
Turbine flow meters are cost-effective and offer reliable, minimal flow meter maintenance required.
A turbine flow meter is a volume sensing device, constructed with rotor and blades. Turbine flow meters use the mechanical energy of the fluid to rotate the rotor in the flow stream. As liquid or gas passes through the turbine housing, it causes the freely suspended turbine blades to rotate. The velocity of the turbine rotor is proportional to the velocity of the fluid.
Rotor movement is often detected magnetically, where movement of the rotor generates a pulse. When the fluid moves faster, more pulses are generated. Turbine flow meter sensors detect pulses externally, outside the flowing stream, avoiding material-of-construction constraints associated with wetted sensors. The RPM of the turbine wheel is proportional to flow velocity within the tube diameter and corresponds to the volume flow over a wide range.
A flow transmitter mounted on the body of the flow meter. Transmitter processes the pulse signal to determine the flow of the fluid. Flow transmitter and sensing systems are available to sense flow in both the forward and reverse flow directions. High-accuracy models are available for custody transfer of hydrocarbons and natural gas.
| Diameter | DN4-DN200 |
| Accuracy | ±0.1%,±0.5%,±0.2%(Optional) |
| Temp. range | -20～+150℃ (OEM) |
| Connection | Thread, flange, tri-clamp |
| Output | Pulse, 4-20mA analog output, RS485 (Modbus-RTU protocol), HART |
| Protection | IP65 or IP68 (Optional) |
| Explosion proof | Exia‖CT4 or Exd‖BT6 |
When selecting a turbine flow meter, several application-specific factors must be considered:
If you need volumetric total flow and/or flow rate measurement, a turbine flow meter is the ideal device. Turbine flow meters are used in a wide variety of liquid and gas flow sensing applications. They can be built to endure high pressure, and high and low temperatures. They offer a high turn-down with minimum uncertainty and excellent repeatability. Turbine flowmeters are also simple to install and maintain only requiring periodic recalibration and service.
A turbine flow meter is used for volumetric total flow and/or flow rate measurement. Turbine flow meter has a simple working principle. As fluid flows through the turbine meter, it impinges upon turbine blades. These blades are free to rotate about an axis along the center line of the turbine housing. The angular (rotational) velocity of the turbine rotor is proportional to the fluid velocity. The resulting output is taken by an electrical pickoff(s) mounted on the flow meter body.
The working principle of the turbine flow meter:
1. Fluid flows through the sensor housing.
2. Because the blade of the impeller has a certain angle with the flow direction, the impulse of the fluid causes the blade to have a rotating moment.
3. Blades rotate after overcoming frictional torque and fluid resistance.
4. After the torque is balanced, the speed is stable.
5. Under certain conditions, the speed is directly proportional to the flow rate.
6. Because the blade is magnetically permeable, it is in the magnetic field of a signal detector (made of permanent magnetic steel and coils).
7. The rotating blade cuts the magnetic field lines and periodically changes the magnetic flux of the coil.
8. Thereby, an electric pulse signal is induced at both ends of the coil.
9. This signal is amplified and shaped by the amplifier to form a continuous rectangular pulse wave with a certain amplitude.
10. Remotely transmitted to the display instrument, show the instantaneous flow rate and cumulative amount of the fluid.
In a certain flow range, the pulse frequency f is proportional to the instantaneous flow Q of the fluid flowing through the sensor.
And the flow equation is: Q = 3600 × f / k
In the formula:
The meter factor of each sensor is filled in the verification certificate by the manufacturer.The k value is set in the matching display instrument, and the instantaneous flow rate and cumulative total can be displayed.
The output frequency of the pickoff is proportional to the flow rate.Each electrical pulse is also proportional to a small incremental volume of flow. This is a major advantage of the turbine flow meter. This incremental output is digital in form. And as such, can be totalized with a maximum error of one pulse regardless of the volume measured. The rimmed rotor improves pulse resolution. Particularly in DN150 (6-in) and larger line size meters.
The turbine flow meter’s expanding blade hanger assembly holds the turbine rotor in alignment with the fluid flow. The angle of the turbine blades to the stream governs the angular velocity and the output frequency of the meter. Flow impinging upon the blade causes the rotor to spin at an angular velocity that is proportional to the flow rate. This design ensures linearity and repeatability. And make the turbine meter an ideal device for flow measurement. The short-term repeatability can reach 0.05 ~ 0.2%. It is precisely because of its good repeatability. Regular calibration or online calibration can achieve very high accuracy.
Turbine flowmeters use the mechanical energy of the fluid to rotate a “pinwheel” (rotor) in the flow stream. Blades on the rotor are angled to transform energy from the flow stream into rotational energy. The rotor shaft spins on bearings. When the fluid moves faster, the rotor spins proportionally faster. Turbine flowmeters now constitute 7% of the world market. Shaft rotation can be sensed mechanically or by detecting the movement of the blades. Blade movement is often detected magnetically, with each blade or embedded piece of metal generating a pulse.
Turbine flowmeter sensors are located external to the flowing stream to avoid material-of-construction constraints associated with wetted sensors. When the fluid moves faster, more pulses are generated. The transmitter processes the pulse signal to determine the flow of the fluid. Transmitters and sensing systems are available to sense flow in both the forward and reverse flow directions.
A turbine flow meter works by placing a free-spinning rotor in the flow path. As fluid passes through the meter body, it pushes against the angled rotor blades and causes the rotor to spin. The rotational speed is directly proportional to the volumetric flow rate of the fluid.
The rotor shaft typically carries a small magnet or ferromagnetic element. Each time the blade passes a pickup coil mounted on the meter housing, it generates an electrical pulse. A flow computer counts these pulses per unit time and converts them to a flow rate using the meter’s K-factor — a calibration constant expressed in pulses per unit volume.
One practical consideration: turbine meters require a fully developed flow profile to produce accurate readings. Install at least 10 pipe diameters of straight pipe upstream and 5 diameters downstream. Flow conditioners can reduce this requirement to roughly 5D upstream in tight installations.
For gas measurement applications, pressure and temperature compensation is essential. Gas volume changes with operating conditions, so a flow computer with built-in P/T correction converts actual volume to standard volume (referenced to standard conditions, typically 15°C and 101.325 kPa).
Like any flow measurement technology, turbine meters have clear strengths and limitations. Knowing both helps you avoid costly misapplication.
A turbine flow meter measures the velocity of liquids, gases and vapors in pipes.
Such as:
The repeatability of the meters ensures quality measurement. Over a wide range of flow rates, temperatures, compositions and viscosities.
High accuracy turbine flowmeters are available for custody transfer of hydrocarbons and natural gas.
A mass flow computer is often used in custody-transfer applications to correct for pressure, temperature and fluid properties. To achieve the desired accuracy.
Oil & Gas
Aerospace/Defense
Pharma-Bio Tech, Food & Beverage
Power Generation
Industrial & Municipal
Cryogenics
Turbine flowmeters measure the velocity of liquids, gases and vapors in pipes. Such as hydrocarbons, chemicals, water, cryogenic liquids, air, and industrial gases. For custody transfer of hydrocarbons and natural gas. High accuracy turbine flowmeters are available. These flowmeters often incorporate the functionality of a flow computer. To correct for pressure, temperature, fluid properties and achieve desired accuracy for application.
Be careful using turbine flowmeters on fluids that are non-lubricating. Because the flowmeter can become inaccurate and fail if its bearings prematurely wear. Some turbine flowmeters have grease fittings for use with non-lubricating fluids. Besides, turbine flowmeters that are designed for a specific purpose. Such as for natural gas service, can often operate over a limited range of temperature (such as up to 60ºC). Whereby operation at higher temperatures can damage the flowmeter.
This flowmeter can be applied to sanitary, relatively clean, and corrosive liquids in sizes up to approximately 24 inches. Smaller turbine flowmeters can be installed in the piping. But larger turbine flowmeters require the installation of substantial concrete foundations and supports. The flow of corrosive liquids can be measured with proper attention to the materials of construction of all wetted parts. Such as the body, rotor, bearings, and fittings.
Applications for turbine flowmeters are found in the water, petroleum, and chemical industries. Water applications include distribution systems within and between water districts. Petroleum applications include the custody transfer of hydrocarbons. Miscellaneous applications are found in the food and beverage, and chemical industries.
Turbine flowmeters are less accurate at low flow rates due to rotor/bearing drag that slows the rotor. Make sure to operate these flowmeters above approximately 5 percent of maximum flow. Turbine flowmeters should not be operated at high velocity. Because premature bearing wear and/or damage can occur. Be careful when measuring fluids that are non-lubricating. Because bearing wear can cause the flowmeter become inaccurate and fail. In some applications, bearing replacement may need to be performed routinely. And increase maintenance costs. Application in dirty fluids should generally be avoided so as to reduce the possibility of flowmeter wear and bearing damage. In summary, turbine flowmeters have moving parts that are subject to degradation with time and use.
Abrupt transitions from gas flow to liquid flow should be avoided. Because they can mechanically stress the flowmeter, degrade accuracy, and/or damage the flowmeter. These conditions generally occur when filling the pipe and under slug flow conditions. Two-phase flow conditions can also cause turbine flowmeters to measure inaccurately.
“To calibrate” means “to standardize (as a measuring instrument) by determining the deviation from a standard so as to determine the proper correction factors.” There are two key elements to this definition: Determining the deviation from a standard. And ascertaining the proper correction factors.
Flow meters need periodic calibration. This can be done by using another calibrated meter as a reference or by using a known flow rate. Accuracy can vary over the range of the instrument. And with temperature and specific weight changes in the fluid, which may all have to be taken into account.
Thus, the meter should be calibrated over temperature as well as range. So that the appropriate corrections can be made to the readings. A turbine meter should be calibrated at the same kinematic viscosity at which it will be operated in service. This is true for fluid states, liquid and gas.
In Volumetric Method technique, flow of liquid through the meter being calibrated is diverted into a tank of known volume. The time to displace the known volume is recorded to get the volumetric flow rate eg:- gallons per minute. This flow rate can then be compared to the turbine flow meter readings.
Sino-Inst is a Turbine flow meter manufacturer, China. Sino-Inst offers over 10 turbine flow meter products. A wide variety of turbine flow meter options are available to you, to suit different applications and budgets. The price of turbine flow meters are decided by flollowing factors:
Choosing the right turbine flow meter starts with matching the meter specifications to your actual process conditions. The table below covers the most common application scenarios and the recommended configurations.
| Application | Medium | Recommended Model | Key Spec Requirement | Notes |
|---|---|---|---|---|
| Water distribution | Clean water | SI-3202 (Liquid) | DN25–DN200, ±1% | Standard 304SS housing is sufficient |
| Petroleum custody transfer | Diesel, gasoline, kerosene | SI-3202 (Liquid) | DN15–DN100, ±0.5% | Requires explosion-proof rating (Ex d IIB T6) |
| Natural gas metering | NG, LPG, biogas | SI-3201 (Gas) | DN25–DN200, with P/T comp | Must comply with AGA 7 or ISO 17089 for billing |
| Compressed air monitoring | Dry air, N2 | SI-3201 (Gas) | DN15–DN100 | Install after dryer and filter to protect rotor |
| Food & beverage | Milk, juice, syrup | SI-3203 (Sanitary) | Tri-clamp connection, 316L | CIP-compatible, FDA-compliant wetted parts |
| Chemical dosing | Solvents, additives | SI-3204 (Flanged) | DN6–DN25, PTFE bearings | Check chemical compatibility before ordering |
| Hydraulic test stands | Hydraulic oil | SI-3202 (Liquid) | DN10–DN50, high-pressure rated | Viscosity compensation may be needed above 10 cSt |
If your application is not listed above or involves unusual conditions (high viscosity, pulsating flow, two-phase flow), contact our engineering team for a custom recommendation. Turbine meters are not ideal for all situations — for slurry or highly viscous fluids, an electromagnetic flow meter or Coriolis meter is a better fit.
A gas turbine flow meter uses the same rotor principle as its liquid counterpart, but the mechanical and electronic design is optimized for low-density, compressible media. Because gas exerts much less force on the rotor blades than liquid does, gas meters use lighter rotors with thinner blades to maintain sensitivity at low flow velocities.
| Parameter | Gas Turbine Meter | Liquid Turbine Meter |
|---|---|---|
| Rotor material | Lightweight aluminum or titanium alloy | Stainless steel 304/316 |
| Bearing type | Ball bearings or ceramic hydrodynamic | Sleeve or ball bearings, fluid-lubricated |
| Pressure compensation | Required — gas density changes with pressure | Typically not needed |
| Temperature compensation | Required — gas volume changes with temperature | Only for high-precision applications |
| Typical accuracy | ±1.0% to ±1.5% of reading | ±0.5% to ±1.0% of reading |
| Common applications | Natural gas custody transfer, compressed air, nitrogen, biogas | Water, petroleum products, chemicals, food-grade liquids |
Pressure and temperature compensation matters because gas is compressible. A cubic meter of natural gas at 5 bar contains roughly 5 times more mass than a cubic meter at 1 bar. Without P/T correction, your totalizer reading would be meaningless for billing or process control. Most gas turbine meters either have built-in P/T sensors or accept external inputs from a pressure transmitter and temperature sensor.
For custody transfer of natural gas (ISO 17089 / AGA Report No. 7), gas turbine meters remain a popular choice because of their wide rangeability (typically 10:1 to 30:1), proven long-term stability, and relatively low pressure drop compared to orifice plates.
Sino-Inst’s SI-3201 Gas Turbine Flow Meter is available in DN15–DN200 sizes with optional built-in P/T compensation and HART or Modbus output.
The SI-3207 small Diameter (small flow) liquid turbine flow meter,is a precision flow measuring instrument,that can be used to measure the flow and total volume of liquids. The structure is explosion-proof and can show the total flow, instantaneous flow and percentage of flow fullness.It is widely used in measurement and control systems in petroleum, chemical, metallurgical, scientific research and other fields. Sensors equipped with sanitary fittings can be used in the pharmaceutical industry.
There are two different manufacturers k:
one is k = f / Q, which is the number of vortices generated per unit flow;
the other is k = Q / f, which is the flow corresponding to each vortex.
The k value is calibrated by the factory water.
The number of vortices of the sensor measuring instrument is compared with the volume flow measured by the calibration device to obtain the k value.
The value of k is actually related to the mechanical structure inside the measuring tube of the flow meter.
Take k = f / Q as an example, the formula is as follows:
Where
D —- Measuring tube diameter
St —- Strauhal number, constant in a certain range of Reynolds number
d —- characteristic width of vortex generator
m–the ratio of the arcuate area on both sides of the vortex generator to the cross-sectional area inside the pipe
The values of d and m are difficult to measure accurately, so it is difficult to obtain accurate k values by calculation.
These three terms often appear interchangeably in search results, but they refer to different levels of a measurement system. Understanding the distinction helps you specify the right product for your application.
| Term | What It Is | Output Signal | Typical Use Case |
|---|---|---|---|
| Turbine Flow Meter | Complete measurement instrument with rotor, housing, and readout electronics | Pulse output, 4–20 mA, or display | Standalone flow measurement with local or remote indication |
| Turbine Flow Sensor | Rotor assembly + pickup coil only — no signal conditioning electronics built in | Raw pulse signal (mV level) | OEM integration where the host system provides signal processing |
| Turbine Flow Transmitter | A flow meter with built-in signal conditioning that outputs a standardized signal (4–20 mA, HART, RS485) | 4–20 mA, HART, Modbus | Process control loops, PLC/DCS integration, SCADA systems |
In practice, most industrial turbine flow meters sold today include transmitter-level electronics — meaning they output 4–20 mA or digital signals out of the box. When you see “turbine flow sensor” in a product listing, it usually means a simpler unit intended for OEM or cost-sensitive applications where the user supplies their own signal processing.
At Sino-Inst, our SI-3201 and SI-3202 models ship with integrated electronics and can be configured as either pulse-output meters or 4–20 mA transmitters, depending on your control system requirements.
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.
