What is Turbine Flowmeter ?

2024/08/08

Table of Contents

What is turbine flow meter and TUF history
Turbine flow meters wide applications around the world
Update flow technology of turbine flow meter all the time
Working Principle of turbine flow meter
What is the formula for calculating turbine?
How do you calculate turbine flow meter factor /coefficient?
Advantages and disadvantages of turbine flow meter
Turbine flow meter types
Turbine flow sensor structure
Accuracy of turbine flow meter
Selection of flow range of turbine flow meter
Flow meter accuracy level for different applications
What fluids can be measured by turbine flow meter?
Turbine flow meter requirements for liquid viscosity
Requirements for gas density for gas turbine flow meter
Conversion of volume flow to mass flow
Application which turbine flow meter is not suitable
Cost when you select turbine flow meter
Steps to choose turbine flow meter
Installation Precautions
Standards and verification procedures

What is turbine flow meter and TUF history

Turbine flowmeter (hereinafter referred to as TUF) is the main type of impeller flow (velocity) meter. Impeller flowmeters also include anemometers, water meters, etc. TUF consists of a sensor and a flow transmitter. The turbine flow sensor uses a multi-blade rotor to sense the average flow velocity of the fluid, thereby deriving the flow rate or total amount. The speed (or number of revolutions) of the rotor can be detected by mechanical, magnetic induction, or photoelectric methods and displayed and transmitted and recorded by a readout device. It is said that the United States issued the first TUF patent as early as 1886. The 1914 patent believed that the flow rate of TUF was related to frequency. The first TUF in the United States was developed in 1938. Turbine fuel flow meter was used to measure the flow rate of fuel on aircraft. It was not until after World War II that jet engines and liquid jet fuel urgently needed a high-precision, fast-response flowmeter that it was truly applied in industry. Today, it has been widely used in various departments such as petroleum, chemical industry, scientific research, national defense, and measurement.
Among flow meters from Silver Automation Instruments, TUF, volumetric flow meter and Coriolis mass flow meter are the three types of products with the best repeatability and accuracy.
TUF also has its own characteristics, such as simple structure, few processed parts, light weight, easy maintenance, large flow capacity (large flow rate for the same diameter) and adaptability to high parameters (high temperature, high pressure turbine flow meter). So far, the flow meter products can reach the technical parameters: diameter DN 4mm~4000mm, users normal buy 2 inch turbine flow meter, 4” turbine flow meter and 8 inch turbine flow sensor. pressure up to 10MPa, temperature -20~150℃.

Turbine flow meters wide applications around the world

TUF is widely used in the following measurement objects: petroleum, organic liquid, turbine flow meter for diesel, inorganic liquid, liquefied gas, natural gas, coal gas, turbine type oil flow meter, turbine flow meter for water, etc. In foreign countries, the transshipment and gathering stations of liquefied petroleum gas, refined oil and light crude oil, as well as the first and last stations of large oil pipelines, all use it for trade settlement. In Europe and the United States, TUF is the natural gas metering flow instrument second only to the orifice flowmeter. In the Netherlands alone, more than 2,600 gas TUFs of various sizes and pressures ranging from 0.8MPa to 6.5MPa are used on natural gas pipelines. They have become excellent natural gas flowmeters.

In the mid-1990s, turbine flow meters sales accounted for about 9% of the total flow meter sales worldwide, with annual sales of about 190,000 units. In China, sales accounted for 20% of the total flow meter sales (excluding household gas meters and water meters) in the early 1990s.
The sales of gas flowmeters (including glass tube float flowmeters) are also around 9%, with annual sales of around 14,000 units. In the mid-1990s, sales declined, but have recently rebounded with the rapid development of the natural gas industry.

Update flow technology of turbine flow meter all the time

Although turbine flow meter is favored by people for its excellent metering characteristics, it gives people the impression that it has moving parts and a short service life, which makes people hesitate when choosing it. After people's unremitting efforts, it should be said that the situation has changed greatly. Due to the use of special wear-resistant bearings, the turbine flow sensor can be used not only for clean media, but also for small particulate media. The average trouble-free working time (MTBF) of a China flow meter factory's product reaches 20,000 hours. The indicator set in the oil (finished oil) pipeline is 8,000 hours, which means that it can basically work continuously for several years, which is consistent with the overhaul period of the instrument. Since the structure of the turbine flow sensor is relatively simple, the maintainability after failure is good, so users can rest assured. According to the Dutch product information, 240 natural gas turbine flow meters that have been used for 8 to 15 years have been periodically calibrated and it was found that the deviation of the accuracy of the instrument is still within the specified range. Silver Automation Instruments sells digital turbine flow meter at economical price cost but still at very reliable operation with several years.
As the most common flow meter, turbine flow meters have developed into a scale of mass production with multiple varieties, full series and multiple specifications.

It should be pointed out that TUF is widely used in some special sectors, such as scientific research, The use of this flow instruments in the fields of testing, national defense science and technology, and metrology just avoids its weakness (not suitable for long-term continuous use).

It can fully play its characteristics (high precision, good repeatability can be used in high pressure turbine flow meter, high temperature, and micro flow turbine flow meter conditions).Most of them are specially designed according to the special requirements of the measured object. They are special instruments and are not batch production.

Working Principle of turbine flow meter

Below figure shows a simplified diagram of the TUF sensor structure. As we can be seen from the figure, when the measured fluid flows through the TUF flow sensor, the fluid acts on the turbine flow sensor.

Turbine flow meter construction

1-Fastener;
2-Housing;
3-Hront guide;
4-Hhrust plate;
5-Impeller;
6-Magnetoelectric induction signal detector;
7-Bearing
8-Rear guide

Under the condition of the impeller being forced to rotate, its speed is proportional to the average flow velocity in the pipeline. The rotation of the impeller periodically changes the magnetic resistance value of the magneto-electric converter. The magnetic flux in the detection coil changes periodically, generating a periodic induced potential, i.e., an electrical pulse signal, which is amplified by the amplifier and sent to the turbine flow transmitter for display.

What is the formula for calculating turbine?

TUF's flow equation can be divided into two types: practical flow equation and theoretical flow equation.
Practical flow equation
qv = f/K
qm = qvρ
Sensing
Where qv—are volume flow rate, m³/s, qm— Mass flow, kg/s;
F —Frequency of flow meter output signal, Hz;
K— The Turbine flow meter’s instrument factor, P/m³.

How do you calculate turbine flow meter factor /coefficient?

The turbine flow meter factor is related to the flow rate (or pipeline Reynolds number)The turbine flow meter factor is related to the flow rate (or pipeline Reynolds number)
The relationship curve of the instrument coefficient is shown in below figure. As can be seen from the figure, the flow measurement instrument coefficient can be divided into two sections, namely the linear section and the nonlinear section.

The linear segment is about two-thirds of its working segment, and its characteristics are related to the TUF flow sensor structure size and fluid viscosity.

The characteristics of the flow measurement instrument factor are greatly affected by bearing friction and fluid viscosity resistance when the flow rate is lower than the lower limit of the sensor flow rate,
As the flow rate changes rapidly, the pressure loss is approximately in a square relationship with the flow rate. When the flow rate exceeds the upper limit, be careful of cavity.
The shapes of the TUF characteristic curves with similar structures are similar, and they differ only in the level of systematic error.

Turbine flow meter characteristic curve

The turbine flow sensor factor is verified by the flow calibration device. It completely ignores the flow mechanism of the fluid inside the sensor. It treats the sensor as a black box and determines its conversion coefficient based on the input (flow rate) and output (frequency pulse signal). It is convenient practical application. However, it should be noted that this conversion coefficient (instrument coefficient) is conditional, and its calibration conditions are reference conditions. If it deviates from this conditional coefficient during use, the coefficient will change. The change depends on the turbine flow sensor type, pipeline installation conditions and fluid physical parameters.

Scholars at China and abroad have proposed many theoretical flow equations, which are applicable to various turbine flow sensor structures and fluid working conditions. To date, the hydrodynamic characteristics of turbine flow meter characteristics are still not very clear, and they have a complex relationship with fluid physical properties and flow characteristics. For example, when the flow field has vortices and asymmetric velocity distribution, the hydrodynamic characteristics are very complex. The Turbine flow meter facotr cannot be derived by theoretical formula, and the turbine flow transmitter coefficient still needs to be determined by actual flow verification. However, the theoretical flow equation has great practical significance. It can be used to guide the design of sensor structure parameters and the prediction and estimation of the law of instrument coefficient changes when the field use conditions change.

Advantages and disadvantages of turbine flow meter

1) High accuracy flow meter: for liquids flow measurement, TUF flowmeter is generally with accuracy of ±0.25%R~±0.5%R, and the high-precision type turbine flow meter can reach ±0.15%R; and for gas flow measurement, the turbine flow meter accuracy is generally ±1%R~±1.5%R, and the special type is ±0.5%R~±1%R. it is quite highly accurate flow meters among all the flow meters.

High accuracy electronic Turbine flow meter from Silver Automation Instruments

2) Good repeatability, short-term repeatability can reach 0.05%~0.2%. Due to its good repeatability, if turbine flow meter is calibrated frequently or online, it can achieve extremely high accuracy.
3) Electronic turbine flow meter: output pulse frequency signal or 4-20mA output, suitable for total quantity measurement and connection with computer, without zero drift and has strong anti-interference ability.
4) Very high frequency signals (3~4kHz) can be obtained with strong signal resolution.
5) Wide range, medium and large diameter turbine flow meter can reach 40:1~10:1, small diameter is 6:1 or 5:1.
6) Turbine flow sensor has compact and lightweight structure, easy installation and maintenance, and large flow capacity.
7) Turbine flow meter is suitable for high-pressure flow measurement, no holes need to be opened on the instrument body, and it is easy to make a high-pressure style flow measurement instrument.
8) There are many types of special turbine flow sensors, which can be designed into various special sensors according to the special needs of users, such as small flow meters, high pressure type flow meters, tri-clamp connection turbine flow meter, high temperature turbine flow meters, etc.
9) It is difficult to maintain the calibration characteristics for a long time and regular calibration is required. For non-lubricating liquids, the liquid contains suspended matter.The abrasiveness of the flowmeter may cause bearing wear and jamming, which limits its application range. The use of wear-resistant carbide shafts and bearings has improved the situation. For trade storage and transportation and high-precision measurement requirements, it is best to equip on-site calibration equipment, which can be calibrated regularly to maintain its characteristics.
10) General liquid turbine flow meter is not suitable for high viscosity media (such as for honey, bitumen or resin flow measurement). As the viscosity increases, the flowmeter lower limit of measurement increases, the range decreases, and the linearity deteriorates.
11) Fluid properties (density, viscosity) have a great influence on flow measurement instrument characteristics. Gas flow meters are easily affected by density, while liquid flow meters are sensitive to changes in viscosity. Since density and viscosity are closely related to temperature and pressure, temperature and pressure fluctuations are inevitable on site. Compensation measures must be taken according to the degree of their impact on accuracy in order to maintain turbine flow meter high metering accuracy.
12) The flow meter is greatly affected by the velocity distribution distortion and rotational flow of the incoming flow. A longer straight pipe section is required on the upstream and downstream sides of the TUF flow sensor. If the installation space is limited, a flow regulator (rectifier) can be installed to shorten the length of the straight pipe section.
13) Not suitable for the flow rate measurement of pulsating flow and mixed flow.
14) The cleanliness requirement for the measured medium is high, which limits its application field. As we all know liquid turbine flow meter only work on clean and low viscosity liquid. Although filters can be installed to adapt to dirty media, it also brings side effects such as increased pressure loss and increased maintenance.

Turbine flow meter types

1) Liquid turbine flow meter
a. Normal type Liquid turbine flow meter is suitable for measuring the volume flow of low viscosity (≤45mPa・s) liquids, with a nominal diameter of DN4~DN300, an accuracy level of 0.25~0.5% , medium temperature of -20~+150℃, and a pressure of 6.3MPa
b. Corrosion-resistant type: Suitable for corrosive fluids such as dilute sulfuric acid, dilute hydrochloric acid, dilute nitric acid, etc., generally only small-diameter products (DN20~DN50).
c. High temperature type: Applicable to liquid temperature below 150℃. The temperature of the measured liquid is limited by the temperature resistance of the detection coil.
d. Tri-clamp type turbine flow meter for hygienic purpose. It can be used to measure drinking water, editable oil, and milk. All stainless steel material turbine flow meter is with tri-clover connection for easy install and easy cleaning.

Tri-clamp electronic turbine flow meter for hygienic purpose from Silver Automation Instruments

e. High pressure type turbine flow meter. Turbine flow meter can be made into high pressure type to bear such as 1000psi, 2000 psi or even higher . Wafer connection type turbine flow meter can be easily made into high pressure type turbine flow meter.

High pressure type digital turbine flow meter

2) Gas turbine flow meter

Gas turbine flow meter measures the flow of clean gas, with a nominal diameter of DN25 ~ DN400, a fluid temperature of -20 ~ +120℃, a pressure of 2.5 ~ 10MPa, and an accuracy level of 1% or 1.5%.

The gas type turbine flow meter is suitable for petroleum gas, artificial gas, natural gas and liquefied petroleum gas, air, N2, CO2, etc. Automatic oilers can be used to lubricate and protect bearings, prevent impurities from entering moving parts, and increase service life. Most of the structures use digital local display devices, and turbine flow transmitter can also be used to output high-resolution pulse signals or 4-20mA or even with HART protocol or MODBUS .

Gas turbine flow meter with automatic oilers to lubricate and protect bearings

Turbine flow sensor structure

The TUF sensor consists of a meter body, a guide body (deflector), an impeller, a shaft, a bearing and a signal detector
1) Turbine flowmeter body: The meter body is the main part of the sensor, which bears the pressure of the measured fluid, fixes the detection components, and connects the pipeline. The meter body is made of non-magnetic stainless steel or hard aluminum alloy. For large-caliber flow sensors, a mosaic structure composed of carbon steel and stainless steel can also be used, and the signal detector is installed on the outer wall of the meter body.

2) Guide body: The guide body is installed at the inlet and outlet of the flow sensor. It guides and rectifies the fluid and supports the impeller. It is usually made of non-magnetic stainless steel or hard aluminum. The rear guide of the reverse thrust turbine flow sensor is also required to generate sufficient reverse thrust, and its structural forms are many. The front guide has a patented product that can resist severe interference with fluid flow.

3) The turbine, also known as the impeller, is the sensor's detection element and is made of highly magnetically permeable materials. Impellers include straight blades, spiral blades, and T-shaped blades. A porous shield ring embedded with many magnetic conductors can also be used to increase the frequency of a certain number of blades. The impeller is supported by a bearing in the bracket and is coaxial with the meter body. The number of its blades depends on the size of the caliber. The geometric shape and size of the impeller have a great influence on the performance of the sensor. It should be designed according to the fluid properties, flow range, and usage requirements. The dynamic balance of the impeller is very important and directly affects the performance and service life of the flow measurement instrument.

The impeller of the turbine flowmeter

4) Shaft and bearings: They support the impeller to rotate and must have sufficient rigidity, strength, hardness, wear resistance, corrosion resistance, etc. They determine the reliability and service life of the turbine flow sensor. Sensor failure is usually caused by the shaft and bearings, so its structure, material selection and maintenance are very important.

5) Signal detectors are commonly used in China. They are composed of permanent magnets, magnetic rods (iron cores), coils, etc. Permanent magnets have an attractive force on the blades, generating magnetic resistance torque. When the flow rate is small for small-diameter turbine flow sensors, the magnetic resistance torque becomes the main item among the resistance torques. For this reason, permanent magnets are divided into two specifications, large and small. Small-diameter sensors are equipped with small specifications to reduce the magnetic resistance torque. Output signals with an effective value of more than 10mV can be directly used with flow computers, and when equipped with amplifiers, they can output volt-level frequency signals.

Accuracy of turbine flow meter

Generally speaking, turbine flow meter is chosen mainly for its high accuracy still at low price cost. At present, the accuracy of TUF turbine flow meter is roughly as follows: for liquids measurement turbine flow meter, the international market is ±0.5%R and ±1%R, for gas flow measurement devcie, is ±1%R and ±1.5%R. The above accuracy refers to the range of 6:1 or 10:1. Typical parameters of turbine flow sensors from Silver Automation Instruments are shown in below table. In addition to being related to the quality of the product itself, accuracy is also closely related to the conditions of use.

If the range is narrowed, the accuracy can be improved; especially for standard flow meters used as standard flow standard devices, if used at fixed points, the accuracy can be greatly improved.

The higher the accuracy of the flow meter, the more sensitive it is to changes in the on-site conditions. In order to maintain its high accuracy, special processing of the instrument coefficient is required. One processing method is the so-called instrument coefficient floating processing method. That is, the following on-site conditions are processed in real time: a) viscosity is affected by temperature; b) density is affected by pressure and temperature; c) sensor signal redundancy (a sensor outputs two signals, and their ratio is monitored); d) long-term stability of the coefficient (determined by a control chart), etc.

For trade storage and transportation handover measurement, online verification devices are often equipped to facilitate regular verification.

The instrument accuracy listed in the turbine flow meter manufacturer's instruction manual is the basic error. The additional error should be estimated on site, and the on-site error should be the combination of the two.

Selection of flow range of turbine flow meter

The selection of the flow range of turbine flow meter has a great influence on its accuracy and service life. Generally, the speed corresponding to the maximum flow during operation should not be too high. The use conditions are divided into continuous flow measurement operation and intermittent flow measurement operation. Continuous operation means that the working time exceeds 8 hours per day, and intermittent operation means that the working time is less than 8 hours per day. For continuous operation, the maximum flow should be selected at the lower limit of the flow instrument's upper limit flow, while for intermittent operation; turbine flow sensor can be selected at the higher limit. Generally, for continuous flow measurement, the actual maximum flow is multiplied by 1.4 as the upper limit flow of the flow range, while for intermittent operation, it is multiplied by 1.3.

If the diameter of the turbine flow sensor is inconsistent with the diameter of the process pipeline, the pipeline should be modified with a reducer and an equal-diameter straight pipe.

For process pipelines with low flow rates, the minimum flow rate becomes the first issue to be considered when selecting the turbine flow sensor size. Usually, the actual minimum flow rate multiplied by 0.8 is used as the lower limit flow rate of the flow range, leaving a certain margin. If the turbine flow transmitter is equipped with a segmented linearization function, when the sensor flow lower limit value cannot meet the actual minimum flow rate, the turbine flow meter manufacturer should be required to perform flow calibration at the actual minimum flow rate and its vicinity, and input the measured instrument coefficient into the turbine flow transmitter, so that the flow lower limit value of the instrument can be reduced while maintaining the measurement accuracy.

Flow meter accuracy level for different applications

The requirements for the accuracy level of the instrument should be cautious and should be considered from an economic perspective. For example, the trade settlement instrument for large-diameter oil (gas) pipelines is of great economic significance, and it is cost-effective to invest more in the instrument. As for the small transmission volume or process control, only a medium level of accuracy is required, and high accuracy should not be blindly pursued. The intrinsically safe explosion-proof sensor is compatible with the safety barrier model and manufacturer, and the explosion-proof level and approval number are checked. If you want to display mass flow (or volume flow under standard conditions), you need to select a pressure, temperature sensor or density meter or choose mass flow meter directly. The turbine flow meter display instrument is now included in the flow computer based on a microprocessor that can communicate with the host computer. The instrument is far superior to the old turbine flow display in terms of instrument functions and applicable scope. At present, all types of flow meters used as trade measurement tend to be equipped with direct reading display devices. Not only is there a display of total measurement, but a compensator (a fully functional flow computer) can also be added to output remote transmission signals.

What fluids can be measured by turbine flow meter?

Turbine flow meter requires that the fluid must be clean (or basically clean), single-phase and low-viscosity. Examples of commonly used fluids are as follows: including turbine flow meter for water, diesel, air, oxygen, high-pressure hydrogen, milk, coffee, etc.; petrochemicals: gasoline, light oil, jet fuel, light diesel, naphtha, ethylene, polyethylene, styrene, liquefied gas, carbon dioxide and natural gas; chemical solutions: amethanol, , etc.; organic liquids: alcohol, ether, benzene, toluene, xylene, butadiene, carbon tetrachloride, methylamine, acrylonitrile, etc.; inorganic liquids: formaldehyde, acetic acid, etc. For corrosive media, attention should be paid to the selection of materials used. It is not recommended to use media with many impurities or abrasive media.

Turbine flow meter requirements for liquid viscosity

Liquid turbine flow meter is a viscosity-sensitive flowmeter. Below Figures show the relationship between the viscosity and the instrument coefficient of the straight blade and spiral blade TUF liquids, respectively. It can be seen from the figure that when the fluid viscosity increases, the linear region of the instrument coefficient becomes narrower and the lower limit flow rate becomes smaller.

Straight blade turbine flow meter coefficient and viscosity relation

Spiral blade turbine flow meter coefficient and viscosity relation

For liquids, water is usually used to calibrate the turbine flow sensor. When the accuracy is 0.5, it can be used for liquids below 5×10-6mm²/s without considering the effect of viscosity. When the fluid viscosity is higher than 5×10-6mm²/s, it can be calibrated with a fluid of equivalent viscosity without making viscosity corrections. In addition, some measures can be taken to compensate for the effect of viscosity, such as narrowing the range of use, increasing the flow rate lower limit, or multiplying the instrument coefficient by the Reynolds number correction coefficient, etc.

The influence of viscosity on the instrument coefficient is related to the sensor structure type and parameters, aperture size, etc. There are several ways to express the effect of viscosity on the instrument coefficient: the relationship between the instrument coefficient and the Reynolds number, the relationship between the instrument coefficient and the output frequency at several viscosities and the relationship between the instrument coefficient and the ratio of the output frequency divided by the kinematic viscosity And so on. Some turbine flow meter manufacturers have this information, but not all manufacturers have it.

In the application of petroleum industry, TUF has been promoted and used because of some characteristics compared with volumetric flowmeter.

The main features are light weight, simple and compact structure, large flow capacity, easy maintenance, tolerance of some impurities without blocking the flow channel, and superior safety. As early as the 1960s, the North Sea Oilfield in the United Kingdom used TUF for crude oil measurement, and Japan's Tokiko also launched a wide viscosity Porter type TUF for heavy oil measurement.

Requirements for gas density for gas turbine flow meter

Gas turbine flow meter mainly considers the influence of fluid density on instrument factor. The influence of density is mainly in the low flow area, as shown in below Figure. The increase of density (i.e. pressure increase) makes the straight line part of the characteristic curve expand to the lower limit flow area, the range of the sensor is expanded, and the linearity is improved. If the gas turbine flow meter is calibrated in air at normal pressure, the working pressure of the measured medium is different during use, and its lower limit flow is calculated by the following formula

Where qVminand qVaminare The lower limit of the volume flow rate of the measured medium and air under pressure p and pressure pa (101.325kPa) respectively, m³/h;
P. Pa- working pressure (absolute pressure) and atmospheric pressure (101.325 kPa), kPa;
d - Relative density of the measured medium, dimensionless.

Gas pressure and factor error relation

Conversion of volume flow to mass flow

Turbine flow meter measures the actual volume flow. Whether it is material balance or energy measurement, it is necessary to measure the mass flow (i.e. standard flow). The volume flow rate under this condition) should be converted by the following formula:

In the formula

qv,qvn – volume flow under operation pressure and standard pressure , m3/h

P,T,Z-Under operation condition absolute pressure(Pa), thermodynamic temperature (K) and gas compressibility coefficient

Pn,Tn,Zn- are respectively the absolute pressure (Pa), thermodynamic temperature (K) and gas compressibility coefficient under standard conditions.

Application which turbine flow meter is not suitable

Fluids with many impurities, such as circulating cooling water, river water, sewage, fuel oil, etc.; places with rapid changes in flow, such as boiler water supply system, air supply system with air hammer, etc.; when measuring liquids, the pipeline pressure is not high and the flow is large, the pressure on the downstream side of the instrument may be close to the saturated vapor pressure, and there is a risk of cavitation. For example, liquid ammonia can flow freely from the high-level tank, so it is not suitable to be installed at the discharge port; near electric welding machines, motors, relays with contacts, etc., there are serious electromagnetic interference places; the length of the upstream and downstream straight pipe sections is seriously insufficient, such as in the engine room of a ship; if the boiler automatic water supply system frequently starts and stops the pump, it will cause impact on the impeller and quickly damage the sensor; when selecting corrosive or abrasive media, you should be cautious and contact the manufacturer for consultation

Cost when you select turbine flow meter

When choosing TUF for high-precision applications, the economic factors should be considered from many aspects. The purchase cost of the turbine flow meter is only part of the cost. The following expenses should also be considered: the cost of auxiliary equipment for installation (such as eliminators, filters, etc.) or bypass branches including valves, etc.; the cost of calibration, in order to maintain high accuracy, it must be calibrated frequently, and even a set of online calibration equipment must be installed on site, which costs a considerable amount; the cost of maintenance, which is used to replace the wearing parts of TUF, which is necessary to maintain high performance.

Steps to choose turbine flow meter

1) Confirm what kind of fluids you will measure?
2) Select the turbine flow meter type. Select according to the physical properties of the fluid. For gas and liquid, use the gas type turbine flow meter and liquid type turbine flow meter respectively. They cannot be used interchangeably. If the viscosity of the liquid exceeds 5mPa•s under working conditions, a high viscosity type should be selected. For acidic corrosive fluids, use the acid-resistant type.
Choose according to environmental conditions, select appropriate instruments according to ambient temperature and humidity, etc. If there is an explosive or flammable atmosphere around, an explosion-proof sensor should be selected.
According to the pipe connection method, the turbine flow sensor can be installed horizontally or vertically. When installed horizontally, the pipe connection methods include flange connection, threaded connection and clamp connection. Flange connection is used for medium-caliber pipes, threaded connection is used for small-size turbine flow meter and high-pressure pipes, and clamp connection is only suitable for low-pressure and small-diameter pipes.
3) Select specifications. According to the on-site use conditions, such as flow range, pipe diameter, fluid pressure and temperature, installation location, etc. and performance requirements, such as accuracy, repeatability, display mode, etc., refer to the turbine flow meter manufacturer's selection sample or instruction manual to select specific specifications and models. You can contact Silver Automation Instruments to get the turbine flow meter specifications. It is also possible that no suitable flow meter can be found and other flow meters have to be selected.

Since there are many types and specifications of TUF, especially the differences in product quality among different turbine flow meter manufacturers, it is necessary to collect as much information as possible on manufacturers and relevant standards, conduct repeated investigations and comparisons before making a decision.

Installation Precautions

Installation place
The turbine flow sensor should be installed in a place that is easy to maintain and where the pipeline is free from vibration, strong electromagnetic interference and thermal radiation. TUF is sensitive to the flow velocity distribution distortion and rotational flow in the pipeline. The flow entering the sensor should be fully developed. Therefore, it is necessary to equip the necessary straight pipe section or flow regulator according to the type of upstream flow blocker of the sensor 2. If the upstream flow blocker situation is unclear, it is generally recommended that the upstream straight pipe section length is not less than 20D and the downstream straight pipe section length is not less than 5D. If the installation space cannot meet the above requirements, a flow regulator can be installed between the flow blocker and the sensor. When installing, measures should be taken to avoid direct sunlight and rain.
Flow Direction
All SILVER turbine flow meters are designed to measure flow in only one direction.
The direction is indicated by the arrow on the body.
Required Lengths of Straight Runs for turbine flow meter
Flow altering device such as elbows, valves and reducers can affect accuracy. See below diagram for typical flow meter system installation.

The recommended guidelines are given to enhance accuracy and maximize performance. Distance given here are minimum requirements; double them for desired straight pipe lengths.
Upstream: allow a minimum straight pipe length at least 10 times the internal diameter of the pipe. For example, with the 50mm pipe, there should be 500mm of straight pipe immediately upstream. Desired upstream straight pipe length is 1000mm.
Downstream: allow a minimum straight pipe length at least 5 times the internal diameter of the pipe. For example, with the 50mm pipe, there should be 250mm of straight pipe immediately upstream. Desired upstream straight pipe length is 500mm.
See below diagram for straight pipe length requirement when there is altering device.

Standards and verification procedures

As one of the main flowmeters for trade settlement in energy measurement, turbine flow meter attaches great importance to the formulation of legal documents all over the world, because it is an important basis for regulating the relationship between supply and demand. The International Organization for Standardization (ISO) promulgates international standards ISO 2715, ISO 9951, and the International Organization of Legal Metrology (OIML) promulgates international recommendations R6, R32.

ISO 2715 is the specification for liquid TUF measurement of liquid hydrocarbons. It stipulates the selection of flow meters and auxiliary equipment, flow conditions, pipeline installation and electrical connections, as well as flow meter performance, use and maintenance.

ISO 9951 is the international TUF standard for gas, which specifies the instrument structure, pressure test, flowmeter characteristics, reading device, field calibration, pressure loss, pipe section installation requirements, etc. In particular, to meet the needs of field installation, the flowmeter is required to be installed without a long straight pipe section under severe flow disturbance, which places extremely high requirements on the performance of the flowmeter product, which is relatively rare among flowmeters.

OIML R6, R32 are international recommendations for gas TUF. From the perspective of measuring instruments, in addition to general flow meter structure and performance regulations, they also make clear provisions for type approval, initial calibration, and subsequent calibration.

The standards of developed industrial countries such as API 2534, AGA NO7, JIS Z8765, JIS B7501, etc. on TUF are summaries of many years of practical use. They are very practical and widely recognized internationally.

China also attaches great importance to the formulation of TUF standards and regulations. As early as the 1980s, the TUF industry standard was promulgated. The standard stipulates terminology, classification, technical requirements, test methods and inspection rules, and introduces installation requirements, the influence of fluid temperature, pressure and viscosity changes on instrument coefficients in the appendix. The standard was revised in 1999. China promulgated the verification regulations in the early 1980s, and it has been revised several times. In addition, TUF, as the standard meter of the standard meter method flow standard device, has formulated a special verification regulation.

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High pressure liquid flow measurement.
Liquid turbine flow sensor DN4-8 inches.VIEW
In-line large size gas turbine flow meter2019/07/30DN350 (14 inches) \DN400 (16 inches) large size gas turbine flow meters can measure the flow of gas or air in closed pipeline. It can measure low pressure or high pressure gas. It is widely used for t...VIEW
Natural gas turbine flow meter2019/08/14Turbine flow meter for natural gas.
Temperature & pressure compensation.
High accuracy : ±1.5%R, ±1.0%R
Natural gas flow meter: 3/4” to 16 inches.VIEW