Piezoelectric vortex flowmeter

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Piezoelectric vortex flowmeter is based on the principle of karman vortex street and successfully de…

Products overview: 
ZW - LUGB seriesPiezoelectric vortex flowmeterHas a good adaptability, medium without compensation can be directly measured temperature and pressure steam, air, gas, water, and the operation condition of the liquid volume of traffic, equipped with temperature and pressure sensors can be used to measure the conditions and the volume flow to mass flow.Parameters can be long-term, stable work, using piezoelectric stress sensor can in - 20 ℃ ~ + 250 ℃ temperature range.There are standard signal simulation and digital pulse signal output, can be used with digital systems, such as computers, and a more advanced and flow of the ideal product.
Second, the working principle: 
ZW - LUGB seriesPiezoelectric vortex flowmeter in the measuring tube vertically inserted a pillars, fluid through the pillars on both sides of the rules of the vortex is alternately, the spiral column is called the karman vortex street.The release of the karman vortex street frequency is related to the width of the fluid velocity and pillars, expressed by the type: 
F = St · v/d type: - the release of the karman vortex street frequency f 
St - coefficient (called, ha) 
V - velocity 
D - the width of the pillars 
Karman vortex street release frequency f and is directly proportional to the velocity v, so by measuring the karman vortex street release frequency to calculate the instantaneous flow rate. 
Stern lo ha is one of the important coefficient of vortex flowmeter.In its number of St 0.17 straight part of the material, the release of the vortex frequency is proportional to the velocity of flow, so check out the velocity v, frequency f can be obtained to calculate volume flow by v. 
Vortex flow sensor be vortex frequency is applied to detect sensor by vortex alternately (probe) on in-situ stress in its internal piezoelectric element to check out. 
Applications: 
ZW - LUGB seriesPiezoelectric vortex flowmeter is widely used in petroleum, chemical industry, metallurgy, machinery, paper, and the city pipe heating, water supply, gas and other industries of all kinds of low viscosity liquid, gas, steam, etc of single-phase fluid process measurement and energy saving management. 
Four, the main features: 
1, with low power consumption CPU processor, and liquid crystal display (LCD), low power consumption. 
2, installation is simple, maintenance is very convenient, the verification cycle is long, generally for two years. 
3, simple structure, no moving parts, long running is very reliable. 
4, span a wide range: 1:10 normal range, the range can be up to 1:15. 
5, small pressure loss, low operating cost, more energy saving. 
6, within a certain Reynolds number, the output signal from the measured media and changes in the composition, physical properties of instrument coefficient only involved in the body shape and size of the vortex, generally do not need to calibrate the instrument coefficient after changing accessories. 
7, scene shows, but also long distance transmission, also can connect with the computer control system. 
8, detecting probe measured medium, not direct contact with more stable performance. 
9, temperature, pressure compensation integration design, the output current are photoelectric isolation, has the good ability to resist common mode interference suppression. 
Five, the technical parameters: 
Piezoelectric type, temperature range: 1: - 25 ℃ ~ + 350 ℃ capacitive: - 40 ℃ ~ + 450 ℃ 
2, the connection way: DN15 ~ 12 for flange mounted flange connection type, from 12 to DN1000 plug-in, DN1000 above are special orders 
And velocity range: 3:7 m/s ~ 70 m/s liquid: 0.7 m/s ~ 7 m/s gas: 5 m/s ~ 35 m/s 
4, pressure specifications: PN1.6 MPa;PN2.5 MPa;Specifications can be customized special PN4.0 MPa, higher pressure 
5, the pressure loss coefficient: Cd 2.6 or less 
6, accuracy: flange mounted, connection type: 0.5, 1.0, 1.5 plug-in: 1.5, 2.5 
7, the power supply voltage: sensors: DC12V or DC24V transmission: DC24V 
The display type: DC24V, DC12V or 3.6 V lithium battery 
8, output signal, sensor, pulse frequency signal 2 ~ 3000 hz low level 1 v high level 6 v or more or less 
Transmitter: two wire system 4 ~ 20 mA DC current signal 
9, ant-vibration performance: piezoelectric capacitive acuities were 2.0 g 0.2 g or less 
: 10, environment temperature sensors: - 30 ℃ ~ + 65 ℃ transmitter: live show - 10 ℃ to + 50 ℃ 
11, environment humidity: 5 ~ 8% relative humidity 
12, signal remote transmission distance: 500 m or less 
13, straight pipe length: 10 d or higher downstream p 5 d 
14, explosion-proof grade: Exia Ⅱ CT2 - T5 safety explosion-proof 
15, protection grade: regular IP65 diving IP68 
16, instrument material: instrument shell adopts aluminium alloy, the table body part adopts 304 stainless steel material, also can according to user requirements the use of special materials.

Six, selection of key points:
Correct selection to ensure that the use of vortex flowmeter is better.Should choose what kind of vortex street flowmeter is based on the current body to determine the physical properties and chemical properties of the medium?Make the size of vortex flowmeter, flow range, lining materials, electrode materials and output current, etc?To be the nature of the flow volume and flow measurement requirements.
1, precision function
Precision grade and function in accordance with the requirements of measurement and choose the instrument using fine grade, cost-effective.Such as for trade settlement, product transfer and energy measurement occasions, should choose high precision grade, such as 1.0, 0.5, or higher level;Used in process control, according to the requirements of control choose not with precision grade;Some just check process flow, without having to do precise control and measurement, can choose lower precision grade, such as 1.5, 2.5, 4.0, and even then you can choose cheap plug-in vortex flowmeter.
2, medium can be measured
Medium velocity and diameter, full scale measurement generally medium, the full flow of vortex flowmeter can measure medium velocity in 0.5-12 m/s within the scope of selection, range is wide.Choose different instrument specifications (diameter) and process piping, the same shall consider whether measuring flow range within the scope of the flow velocity, namely when the pipeline flow rate is low, can not meet the requirement of the flow meter, or under the velocity measurement accuracy of the quasi cannot guarantee, the need to reduce the size instrument, which carry high tube flow velocity, measurement results are satisfied.
3, the selection of vortex flow transmitter
In saturated vapor measurement using VA type piezoelectric vortex flow transmitter, due to the vortex flow meter range wide, therefore, in practice, the measurement of saturated steam flow main consideration shall not be less than the lower limit of vortex flowmeters, that is to say, must satisfy the fluid flow rate shall be not less than 5 m/s.According to the size of the YongQiLiang chooses different caliber of vortex flow transmitter, rather than with the existing technology to choose transmitter diameter pipe size.
The choice of 4 pressure transmitter, pressure compensation
Because of the saturated steam pipe length, pressure fluctuation is bigger, pressure compensation must be used, considering the pressure, temperature and density, the relation between measurement using pressure compensation, because the pipeline saturated steam pressure in the range 0.3 0.7 MPa, pressure transmitter ranges 1 MPa.
5, display instrument selection
Display instrument intelligent flow display, a voltage compensation, the instantaneous flow and cumulative flow integrating function.
Seven, field requirements:
1, low maintenance - most of the vortex flowmeter are on the market with induction swirl hole or plug-in measurement, once the impurities embedded in the medium pressure hole or sensing element and the table body, the gap between the signal is weak or unstable.A good design should be not easy to plug part, thereby reducing amount of maintenance.
2, inductive components online replacement - some manufacturer of inductive components and vortex street close 2 for one, seemingly simple design to the actual use of inconvenience.Because once induction part failure, you need to medium to the pipe emptying replacement parts, after pressure relief effect production.Perfect design should be separated the two, so can replace the induction part alone, without emptying the media.
3, vortex flowmeter is vulnerable to vibration interference, well-designed vortex flowmeter can through hardware and digital signal processing to exclude interference, and the stability of the signal is obtained.
4, vortex flow meter before and after the installation of a hassle to very long straight section, some manufacturers can offer within the flowmeter reducing design, greatly reduces the user specifically MenWei vortex flowmeter with the demand of the straight pipe.

Eight, the dimensions:

Nine, pipe requirements:
1, the requirement for straight pipe:
In order to ensure that the instrument, accurate to run normally, sensor must have a certain straight pipe upstream and downstream of the installation points, to adjust the flow field, as shown.

Figure 1: concentric contraction tube;
Figure 2: the concentric expansion tube;
Figure 3: a 90 - degree Angle;
Figure 4: the same plane of two 90 - degree Angle;
Figure 5: different plane of two 90 - degree Angle;
Figure 6: regulating valve should be installed downstream of the sensor in 5 d to the distance, if the sensor must be installed in the upstream, the sensors should be not less than 50 d upstream, straight pipe section downstream straight pipe section should be not less than 5 d.
2, the requirement of pipe:
A, upstream and downstream piping diameter D and the same as the sensor inner diameter DN, its difference satisfy the following conditions: 0.95 DN D 1.1 or less or less DN.
B, piping shall be concentric with sensor, coaxial degree should be less than 0.05 DN.
C, gasket not protruding into the pipe, the inner diameter slightly larger than sensors.
D, if you want to stop inspection and cleaning the sensor, the by-pass pipe should be set up,As shown in the figure below.

 
3, the requirement of pipe vibration:
Sensors to avoid installed on the strong pipeline vibration, if necessary to install, shock absorption measures must be taken, respectively at the upstream and downstream of sensor 2 d piping fastening device, and vibration-proof pad.
Special note: in the air compressor exit strong vibration, cannot install the sensors, shall be installed after the gas storage.
4, demand for air condition:
A, the gas to be tested for single phase pipe flow, continuously flowing through a pipe.
Before b, the gas flows through the flowmeter, the flow rate must be parallel to the pipe axis, can not have vortex flow.
C, flow should be a subsonic, a pulse, its flow change slowly over time.
5, the flowmeter installation requirements:
Vortex street flowmeter to process the installation and use of the special requirements of environment is not too much, but any kind of flow measurement instrument has such a common, as far as possible to avoid vibration and high temperature environment as flow interference elements (such as compressor, separator, pressure regulating valve, reducer, and pipe, elbow, etc.), keep straight pipe before and after the instrument inside sleek straight, ensure to clean single-phase fluid measured medium, etc.

Ten problems need to pay attention to during using, debugging:
1, flowmeter, on-site installation, maintenance, must abide by the "explosion-proof gas do not open" warnings, and in the open before turn off the power supply.
2, vortex flow meter used in outdoor, suggestion and side shields.
3, shall not be arbitrarily fixed part loosen the flowmeter.The protection of the pressure sensor.Users in the use of traffic time, should pay attention to the flow pressure overload value of pressure sensor is rated working pressure of 1.5 times (that is, the media zui high pressure of 1.5 times).Selection should be within the prescribed flow range, prevent overspeed operation, in order to obtain the ideal accuracy and ensure the normal service life.(due to pressure test, purging pipes or exhaust overdrive, and turbine operation in the reverse flow meter can cause damage)
4 when put into operation, the vortex street flowmeter, should slowly open valve, prevent damage of instantaneous flow and the turbine.Add lubricant should be according to the sign, the number of refueling depends on temperament clean degree, usually 2 ~ 3 times a year.
5, vortex street flowmeter runtime or alternate internal related parameters are not allowed to open the rear cover, otherwise will affect the normal operation of the meter.
Eleven, install and use should be paid attention to in the items:
Vortex street no mechanical moving parts, small size, corrosion resistance, stable performance, can be directly display medium work pressure, temperature, flow rate and volume under standard state, wide range, the advantages of small measurement error, has been widely used in oil and gas well production measurement and gas sales.In field application over the years, we believe that the meter is suitable for relatively clean dry gas metering, gradually become small and medium-sized gas metering.To guarantee the accuracy of the flowmeter measurement, reduce the measuring error, please note:
1, the selection of reasonable
Don't make the actual zui small flow meter QVmin below the selected through runoff flow range limit.
2, installation is correct
Upstream of the vortex flowmeter should have at least 10 d measuring straight pipe length.Straight pipe inner surface should be smooth, cannot have the steps, more smooth connecting flange weld, flange gasket can't into the pipe.Don't put the wrong installation direction of the flow meter.Tests showed that: all the unreasonable installation, will lead to the flowmeter measurement value is low.
3, away from the source of shocks, or install piers in upstream or downstream flow meter, in order to avoid the influence of the pipeline vibration.Avoid strong magnetic field disturbance to the flow meter chip.
4, temperament is relatively clean
Especially not a gas liquid two phase flow;Temperament is dirty, should clean instant flow meter.
5, and reduce the influence of flow pulsation
It can be installed in front of the flow meter buffer tank, or extended length of straight pipe upstream of the flow meter, computation.
6, timely flowmeter for metrological verification, to ensure accurate and reliable value.

Twelve, selection guidelines:

Determine the structure of the sensor

1, connection mode: flange card mounted body without flange (table) or flange connection type (table body itself with flange).General advice to choose flange mounted, because of its compact structure, low price, and short delivery cycle.

2, the structure type: one-piece structure and split type structure.Generally USES the one-piece structure, only on special occasions, adopts the split type structure (such as: medium at high temperature, environmental temperature or humidity is high, with the scene display for easy reading).

3, display mode: no scene shows, with the scene display and carry only the scene.Scene shows refers to on the header is equipped with LCD display, can display the cumulative flow and transient flow parameters, such as.

4, the signal output way: the pulse signal output and 4 ~ 20 ma current standard signal output.The pulse signal output normally recommended, because directly and vortex shedding frequency corresponding to the pulse signal, without conversion, has a zui high accuracy;At the same time, in the usual transmission distance, pulse signal transmission effect is better.Standard and is commonly used in current signal output terminal or control system of the flow measurement system.

5, explosion-proof forms: the explosion proof type and safety explosion-proof type.If the medium to be measured is flammable and explosive substances or measuring environment is flammable and explosive substances, should choose explosion-proof type.

Determine the configuration of the vortex flowmeter:

1, the density compensation:

When measuring the mass flow rate of steam, due to its density changes with the change of temperature and pressure, so to compensate for steam, at any time with a platinum thermal resistance and pressure transmitter with vortex sensor with mass flow measurement system.There is a measurement of saturated steam and superheated steam, to be stable if the temperature and pressure to reduce the equipment cost, can also according to the working state, by setting a fixed value density compensation.Other media can according to the actual situation of mass flow measurement system.

2, of intelligent flow totalizer.especially options:

Requires only display parameters, can choose digital display or LCD display; intelligent flow totalizer.especiallyNeed to trace the historical data, with memory function, should choose intelligent flow settlement paperless recorder;Measure the full and steam, should choose with automatic temperature compensation density or pressure; automatic compensation of density flow totalizer.especiallyMeasurement of superheated steam, should choose along with temperature and pressure compensation density flow integrating instrument;Using the remote communication, should consider intelligent flow totalizer.especially with RS485 and RS232 communication interface.Requirements and control system of the flow measurement system, intelligent flow integrating instrument should take 4 ~ 20 ma standard current signal output interface;

When needed, should configure a backup power supply, so that all of a sudden power failure meter can be measured normal.When needed, should with meter box, place the intelligent flow integrating instrument, instrument box, with a lock made of intelligent flow totalizer.especially set parameters cannot be adjusted freely, with anti-theft function, at the same time, the instrument is equipped with protection circuit in the oven, play a role of protection of intelligent flow totalizer.especially.

3, remote monitoring: in need multi-point measurement, distribution area is larger, the need for real-time monitoring, can use the GSM/GPRS communication network or wireless private network remote traffic monitoring system, realize real-time monitoring and management of the pipeline flow.

4, the determination of the calibre of the sensor, the sensor diameter is different, its measuring range is different, and each kind of caliber its measuring range as the measured medium type and condition of the change of temperature, pressure change, first determine the medium under the working condition.

Thirteen, standard of flow range profile: unit (m3 / h)

14, selection of coding:

15,Order to choose selection guidelines:

Name and model number of 1, 1), (2) the diameter, flow range, (3) whether or not to bring the attached so that we can correct selection for you, (4) using pressure, (5) the use of medium temperature.

2, if has been selected by design units in the way of vortex street flowmeter types, please press type vortex flowmeter directly order from our sales department.

3, when using occasions is very important, or the environment is complex, please try to provide the design drawings and detailed parameters, by wei experts in our audit checks for you.

After-sales service commitment:

1, from the date of signing of the contract, I in the way provided for products of the company offers free maintenance and maintenance service, commitment to lifelong maintenance service;

2, jiangsu wei measurement and control instrument co., LTD. Sales manager will be in regular contact with customers, understand the usage of products, and solve the problems of the customers to use in the process of produce, free of charge to provide technical support;

3 the man-made damage is found, the warranty period, our company is responsible for the maintenance, and the resulting maintenance fee;

4, product quality problems or are not satisfied with product, the user can choose unconditional return, wei tt&c don't charge any fees, appear quality problem, bear the freight back and forth.