FAQ for Vortex Gas Flowmeter

1. What’s the vortex gas flowmeter？

Vortex gas flowmeter is mainly used to measure the flow of industrial pipeline medium fluid, like gas, air, steam, and other media.

Gas flowmeter technology to solve the application of similar products to detect the probe body directly in contact with the measured medium and the measurement medium temperature is not high, maintenance is not convenient and other problems.

JC080 series gas flow sensor simultaneously with a wide range of all the sensor’s patented technology, process, and characteristics. It is particularly suitable for high-temperature fluid media. Average temperature fluid conditions can not stop production, cut off the flow of maintenance occasions, and significantly expand the scope of application of the steam flow meter.

Vortex gas flow meter is characterized by slight pressure loss, an extensive range, high accuracy. In measuring working conditions, the volume flow is almost independent of the fluid density, pressure, temperature, viscosity, and other parameters.

The vortex gas flow meter uses a piezoelectric stress sensor, which is highly reliable and can work in the operating temperature range of -20°C to +250°C. Standard analog signals and digital pulse signal output are common, easy to use with computers and other digital systems, are a more advanced, ideal flow meter.

The vortex gas flowmeters strictly implement the national industry standard (JB/T9279-1999) and metrological testing regulations (JJG198-94) for the current industrial metering energy management and engineering design to provide a professional standard in line with the latest type of vortex gas flowmeter.

2. What’s the working principle of the vortex gas flowmeter？

In the gas fluid set triangular column vortex generator, then from the vortex generator on both sides of the alternate generation of the regular vortex, this vortex is called Carmen vortex, vortex column in the vortex generator downstream asymmetric arrangement.

Set the frequency of the vortex is f, the measured medium’s average velocity is U1, the vortex generation surface width is d, the diameter of the meter body is D, and the following relationship can be obtained.

f=SrU1/d=SrU/md (1)

U1 – the average flow velocity on both sides of the vortex generator, m/s.

Sr – the Strohal number.

m – the ratio of the bowed area on both sides of the vortex generator to the cross-sectional area of the pipe

The volume flow rate qv in the pipe is

qv=πD2U/4=πD2mdf/4Sr (2)

K=f/qv=[πD2md/4Sr]-1 (3)

Where K – meter coefficient of the meter, number of pulses/m3 (P/m3).

K is related to the Strawhal number, vortex generator, and pipe geometry. Strawhar number is a dimensionless parameter related to the shape of the vortex generator and Reynolds number. In the range of ReD = 2 × 104 ~ 7 × 106, Sr can be regarded as a constant, which is the normal operating range of the meter.

When measuring gas flow, the VSF flow rate calculation formula is (4) formula qVn, qV – respectively, the intermediate state (0oC or 20oC, 101.325kPa), and the volume flow rate under working conditions, m3 / h.

Pn, P – is the absolute pressures in the standard state and under working conditions, respectively, Pa.

Tn, T – the thermodynamic temperature at standard and working conditions, respectively, K.

Zn, Z – is the compression coefficients of the gas at the normal state and the working condition, respectively.

As can be seen from the above formula, the output pulse frequency signal is not affected by changes in fluid properties and components. The instrument coefficient in a specific Reynolds number range only with the vortex generator and the shape and size. Of the pipe, etc… But as a flowmeter in the material balance and energy metering need to detect the mass flow, when the output signal of the flowmeter should be monitored at the same time volume flow and fluid density, fluid properties and components of the flow measurement or have a direct impact.

According to the Karman vortex principle, a vortex gas flowmeter is designed to measure the volumetric flow of gases, steam, or liquids and the volumetric or mass flow in the normal state. Therefore, it can be used as a flow transmitter in automatic control systems. Furthermore, because of its good adaptability to the medium, steam, air, gas, water, liquid volume flow can be directly measured without temperature and pressure compensation. On the other hand, pressure sensors can measure the standard volume flow with temperature, and mass flow is the ideal alternative to the throttle flow meter.

Vortex gas flowmeter measurement principle of saturated steam flow measurement in the 80s people generally use standard orifice flowmeter, but from the flow meter development situation, orifice flowmeter despite its long history, a wide range of applications; people on its research is also the most adequate, the perfect test data, but the standard orifice flowmeter to measure the flow of saturated steam, it still has some shortcomings: one, the pressure loss is more significant; second, the guide tube, between the three groups and the connection joint is easy to leak; third, the range is small, generally 3 to 1, the flow fluctuations are easy to cause the measured value is low. The vortex flowmeter has a simple structure, vortex transmitter directly installed in the pipeline, to overcome the phenomenon of pipeline leakage. Therefore, with the maturity of the vortex flowmeter measurement technology, vortex flowmeter is increasingly popular.

JC series vortex gas flowmeter using advanced differential technology, with isolation, shielding, filtering, and other measures to overcome the poor shock resistance of similar products, small-signal data disorder, and other problems, and the use of a unique sensor encapsulation technology and protective measures to ensure the reliability of the product. The products are available in two types, compact and remote. The compact type measures a single flow signal; the remote type can simultaneously measure temperature, pressure, and flow. Each type has an integral, split structure to adapt to different installation environments.

3. What are the technical parameters of the vortex gas flowmeter？

☆Nominal through-put: DN50mm~DN500mm.

☆Instrument material： SS or CS

☆Nominal pressure (Mpa) PN1.6Mpa; PN2.5Mpa; PN4.0Mpa

☆The temperature of the measured medium (℃) -40～+250℃; -40～+350℃

☆Environmental conditions Temperature -10～+55℃, relative humidity 5%～90%, atmospheric pressure 86～106Kpa

☆Accuracy level Measuring liquid: ±0.5 % of the indicated value

☆Measurement of gases or vapors: ±1.0, ±1.5 of the indicated value

☆Range ratio 1:10; 1:15

☆Resistance loss factor Cd<2.6

☆Output signal Sensor: pulse frequency signal 0.1 ~ 3000Hz low level ≤ 1V high level ≥ 6V

☆Transmitter: 2-wire 4 ~ 20mADC current signal

☆Power supply Sensor: +12VDC, +24VDC (optional)

☆Transmitter: +24VDC

☆Field display type: the instrument comes with a 3.2V lithium battery

☆Signal transmission line STVPV3×0.3 (three-wire system), 2×0.3 (two-wire system)

☆Transmission distance ≤500m

☆Signal line interface Internal thread M20×1.5

☆Explosion-proof class ExdIIBT6

☆Protection class IP65

☆Permissible vibration acceleration 1.0g

☆Accuracy: 1.0 class for liquids, 1.5 class for gases (within the standard flow range).

☆Repeatability: 0.2%, 0.3% .

4. What are the advantages of the vortex gas flowmeter？

☆No moving parts, long-term stability, simple structure for easy installation and maintenance

☆Anti-vibration circuitry and anti-vibration sensing head, with specific anti-ambient vibration performance

☆Ultra-low power consumption single-chip microcomputer technology, 1 x 3.2V10AH lithium battery can be used for more than five years

☆Correction of the non-linearity of the instrument coefficient by software to improve the measurement accuracy

☆Slight pressure loss and a wide measuring range

☆EEPROM is used to protect the accumulated flow rate from power failure for more than ten years

5. What are the application of vortex gas flowmeters？

Vortex gas flowmeter is mainly used for industrial pipeline medium fluid flow measurement, such as gas, liquid, steam, and other media. Vortex gas flow meter is characterized by slight pressure loss, an extensive range, high accuracy in measuring the volume flow of working conditions almost independent of fluid density, pressure, temperature, viscosity, and other parameters. No movable mechanical parts, therefore high reliability and low maintenance. Instrument parameters can be stable over time. The vortex gas flow meter with a high-reliability piezoelectric stress sensor can be in the -20 ℃ ~ +250 ℃ operating temperature range. Standard analog signals and digital pulse signal output are common, easy to use with computers and other digital systems, are a more advanced, ideal flow meter.

7. What are the uses of vortex gas flowmeter？

Vortex gas flowmeter can be widely used for large, medium, and small various pipeline water supply and drainage, industrial circulation, sewage treatment, oil, chemical reagents, and compressed air, saturated and superheated steam, natural gas, and various media flow measurement.

8. What are the installation requirements of the vortex gas flowmeter？

I. Requirements for pipeline installation

Vortex gas flowmeter in the installation point of the upstream and downstream straight pipe section has specific requirements. Otherwise, it will affect the medium in the pipeline flow field and thus jeopardize the flowmeter measurement accuracy.

Note: The regulating valve should not be installed upstream of the vortex flowmeter as far as possible but should be installed downstream of the vortex flowmeter 10D.

(I) The inner diameter of the upstream and downstream piping should be the same. If there is a difference, the piping inner diameter Dp and vortex flowmeter inner diameter Dp, should meet the following relationship: 0.98 Db ≤ Dp ≤ 1.05 Db, upstream and downstream piping should be concentric with the flow meter inner diameter, the different axis between them should be less than: 0.05 Db.

(II) the instrument and the flange between the gasket in the installation can not be convex into the tube. Its inner diameter should be 1-2mm, more significant than the internal diameter of the meter.

II. Installation steps

(I) according to the opening size requirements on the pipe opening, with the position of the entrance to meet the needs of the straight pipe section.

(II) will be connected to the flange of the whole flowmeter set into the pipe’s open mouth.

(III) The two flanges on both sides of the implementation of welding positioning. Remove the flowmeter, weld the flange as required, and clean all protruding parts in the pipe.

(IV) in the inner groove of the flange is installed with the pipe through the same sealing gasket, the flowmeter into the middle of the flange, make the flowmeter flow direction mark and fluid direction, and then connected with bolts suitable.

III. Horizontal pipeline installation

When measuring gas flow, if the measured gas contains a small amount of liquid, the flowmeter should be installed in the higher part of the pipeline.

IV. Installation on vertical pipelines

(I) when measuring gas, the flowmeter can be installed in the vertical pipeline, and the flow direction is not limited.

(II) If the measured gas contains a small amount of liquid, the gas flow should be from the bottom up.

IV. Installation precautions

(I) flowmeter installation must be carried out by the requirements to avoid damage to the instrument due to improper installation and affect the accuracy of measurement.

(II) flowmeter should try to avoid installation in the overhead longer pipeline. The sagging of the pipeline is easy to cause the flowmeter and the seal between the flange leakage. If it must be installed, it must be set in the flowmeter upstream and downstream 2D at the pipeline support points.

(III) If the measured medium needs to be temperature and pressure compensation (such as steam, compressed air), the pressure measurement point should be in the flowmeter downstream about 3 ~ 5D, the temperature point should be in the flowmeter downstream 4 ~ 8D, as shown in the following chart.

(IV) in the measurement of steam in the pipeline, to prevent the converter temperature is too high, at least half of the instrument connecting rod does not insulate (as shown in the figure) to facilitate observation and wiring, the meter head in the original position can be rotated 360 degrees, after adjusting the position, the locking nut can be tightened. If the flowmeter head installation direction is down, you need waterproof tape to lock the nut wrap seal.

The above is about the vortex flow installation steps and precautions. The correct installation can effectively ensure the measurement accuracy of the vortex flowmeter. If you want to learn more about the selection of vortex flowmeter, installation, troubleshooting, and other issues, please consult our engineers.

9. What are the requirements of the external environment for the vortex gas flowmeter？

☆Avoid solid electrical equipment, high-frequency equipment, and robust switching power supply equipment wherever possible. The instrument’s power supply should be separated from these devices as far as possible to prevent interference from outside.

☆Avoid high humidity environments and robust corrosive gas environments. If installed, ventilation measures must be in place.

☆In the high-temperature heat and radiation sources and other direct influence of the environment, the installation should be avoided as far as possible, such as can not choose, must have insulation ventilation measures.

☆As far as possible to select in the vibration of weak pipe section installation, such as can not be avoided, need to be in its upstream and downstream 2D at the addition of pipe fastening devices, and increase the anti-vibration pad, strengthen the effect of anti-vibration.

☆The instrument can be installed indoors as far as possible. Still, when installed outdoors, attention should be paid to waterproofing, especially at the electrical interface where the cable should be bent into a U-shape to avoid water entering the amplifier housing along the line.

☆When choosing the installation point of the meter, the surrounding area should be left with relatively ample space for installation and wiring and later maintenance.

☆Steam vortex flowmeter is best installed indoors, must be installed outdoors, and must be used to protect the sun, rain, and lightning measures from affecting the service life.

10. What are the precautions for the use of vortex gas flowmeter？

☆The vortex flowmeter should not be strongly bumped or wetted by rain during transport.

☆Use our packaging to deliver the flowmeter directly to the installation site whenever possible.

☆When you get the flowmeter, please ensure no bumps and scratches in transit, etc.

☆Check that the product nameplate matches the model you are buying.

☆Store the product in its original packaging as far as possible.

①in a place where it will not be exposed to rain or water

② Where there is minimal vibration or impact

③ Temperature: -40°C to +55°C

④ Humidity: 5% to 90%

☆Used vortex flowmeter storage to clean the internal residual liquid and adhesions completely, in addition, ，to paying attention to the power supply interface to seal to prevent moisture.

☆If the flowmeter is damaged, the repair costs will be borne by you.

☆After the vortex gas flowmeter problems, as far as possible, contact the repair dealer or us, do not blindly repair yourself.