CASES

  Summarization   Vortex flowmeter is a flow measurement instrument based on the Karman vortex flowmeter principle, also known as vortex flowmeter or Karman vortex flowmeter. It is mainly used to measure the volume flow of gas, steam or liquid in various pipelines. It is a new type of flow meter commonly used in industrial control, energy metering and energy saving management, and is widely used in industrial production, energy metering, environmental protection, transportation and other fields.   Working principle   Vortex flowmeter is an instrument that uses regular vortex stripping phenomenon to measure fluid flow. When a non-streamlined column (cylinder or triangular column) is vertically inserted into the fluid as a vortex generator. When the Reynolds number reaches a certain value, there will be two columns of alternating vortices in the downstream of the column, because these vortices are like street lights next to the street, so it is called "vortex street", this phenomenon was first discovered by Karman, also known as "Karman vortex street".   At the back of the object are neatly arranged vortices that turn in opposite directions along two parallel lines.   The number of these vortex rows, the vortex frequency, is proportional to the flow rate of the fluid. By measuring the frequency of the vortex, the flow rate of the fluid can be deduced, and the flow rate of the fluid can be calculated.   Product picture      Peculiarity   Vortex flowmeter is characterized by high precision, wide measuring range, no moving parts, no mechanical wear, easy maintenance, small pressure loss, energy saving effect is obvious. However, the vortex flowmeter is not suitable for low Reynolds number, for high viscosity, low flow rate, the use of small diameter has limitations, the flowmeter installation should have enough length of the straight pipe section, the length of the upstream and downstream straight pipe section is not less than 20D and 5D, and should try to eliminate vibration.   The frequency of vortex in vortex flowmeter is not affected by temperature, pressure and viscosity, so it has high measurement accuracy.     Application field   The application range of vortex flowmeter is quite wide, mainly including the following areas:     Industrial production: In metallurgy, power, coal, chemical, petroleum and other industries, vortex flowmeters are used to measure and control the flow of various fluids (including gas, liquid and steam) to meet the needs of the production process.   Energy metering: In the field of energy measurement, vortex flowmeters can be used to measure the flow of primary energy (such as coal, crude oil, coal bed methane, liquefied petroleum gas and natural gas) and secondary energy (such as electricity, coke, artificial gas, refined oil, liquefied petroleum gas, steam) and energy-carrying working medium (such as compressed air, oxygen, nitrogen, hydrogen, water). It provides an important basis for scientific management of energy, realizing energy saving and consumption reduction and improving economic benefits.   Environmental protection: In the field of environmental protection, vortex flowmeters can be used to monitor and control the discharge flow of flue gas, waste liquid, sewage, etc., which helps to improve the quality of atmospheric and water resources.   Transportation: In the field of transportation, vortex flowmeter is a key tool for control, distribution and scheduling in pipeline transportation, and can achieve accurate control and management of the transportation process by measuring the flow of fluid in the pipeline.   In summary, vortex flowmeter is a kind of flow measuring instrument with high precision, wide range, good stability, strong adaptability and wide application. With the continuous development of industrial automation and technological progress, the application prospect of vortex flowmeter will be broader.                                                                                                                                                                                                                                                        The  End    

Piezoresistive pressure transmitter as below picture is characterized by its small size and simple structure. The sensitivity coefficient of diffusion resistance is dozens of times that of metal strain gauge, and can directly measure small pressure changes. In addition, piezoresistive pressure transmitters also have good dynamic response and low hysteresis, which can be used to measure pulsating pressures of several thousand Hertz or even higher. This is a relatively rapid development, very widely used pressure transmitter.     Capacitive pressure transmitter adopts differential capacitance as detection element, which mainly includes measurement and conversion amplification. The differential signal is converted into differential capacitor signal by the central pressure sensing diaphragm and the left and right curved capacitor plate, and the central pressure sensing diaphragm forms a capacitor with the left and right curved capacitor plate respectively. The differential pressure causes the central pressure sensing diaphragm to produce displacement, so that the distance between the movable electrode and the left and right fixed electrodes is no longer equal, forming a differential capacitance, and the relative change value of the differential capacitance is linear with the differential pressure. Due to the mechanical transmission mechanism without lever inside the whole capacitive differential pressure transmitter, it has the characteristics of high precision, high stability and high reliability, and its accuracy level can reach 0.2, which is a kind of transmitter commonly used in industry.   The piezoelectric pressure transmitter uses the piezoelectric effect of the piezoelectric material to convert the measured pressure into an electrical signal. It is a commonly used sensor in dynamic pressure detection, and is not suitable for measuring slowly changing pressure and static pressure. The vibration frequency pressure transmitter uses the relationship between the resonant frequency of the pressure sensing element itself and the pressure to detect the pressure by measuring the change of the frequency signal. This kind of sensor has a variety of forms such as vibrating drum, vibrating string, vibrating film, quartz resonance, etc. The instrument has small size, output frequency signal, good repeatability and vibration resistance. High precision, suitable for gas measurement.   Application: Pressure transmitters are widely used in various industrial fields, such as petroleum, chemical, metallurgy, electric power, pharmaceutical, water treatment, etc., for measuring and controlling the pressure of various fluids to ensure the stability and safety of the process.   They can measure a wide range of pressures from tiny to extremely high, with high precision, high stability, high reliability and long life. In addition, according to the different measurement principles and application scenarios, pressure transmitters can also be divided into a variety of types, such as differential pressure transmitters (used to measure the difference between two pressures), absolute pressure transmitters (used to measure the absolute pressure relative to vacuum), gauge pressure transmitters (used to measure the pressure relative to atmospheric pressure) and so on.                                                                                                           The End 

The device that can detect the pressure value and provide a remote signal is collectively referred to as the pressure transmitter, which is a sensor commonly used in industrial automation process control to measure the pressure of a gas or liquid, and convert this pressure value into a measurable and transferable electrical signal.   These electrical signals are typically standard current or voltage signals, such as 4-20mA current signals or 0-10V/0-5V voltage signals, to facilitate remote transmission, display, recording or control in industrial automation, process control, monitoring and measurement systems.   It can meet the requirements of centralized detection and control of automation system, and is widely used in industrial production.   Composition of pressure transmitter: The pressure transmitter usually consists of a pressure sensitive element (such as a strain gauge, capacitor diaphragm, piezoresistive chip, etc.) and a signal processing circuit. When the measured medium acts on the pressure sensitive element, it will cause some physical change in the element (such as resistance change, capacitance change, resonant frequency change, etc.), which is then converted into an electrical signal. The signal processing circuit is responsible for amplifying, linearizing, and temperature compensating this electrical signal to output a stable and accurate pressure value.   Types of pressure transmitters The structure of the pressure transmitter is varied, according to the working principle, there are strain type, piezoresistive type, capacitance type, piezoelectric type, vibration frequency type and so on. The following is a brief introduction to several commonly used pressure transmitters. The strain gauge pressure transmitter has a large measuring range, the measured pressure can reach hundreds of mpa, and has good dynamic performance, suitable for rapidly changing pressure measurement. But there are more obvious temperature drift and time drift, this instrument is more used in the general requirements of dynamic pressure detection; Piezoresistive pressure transmitter is manufactured according to the piezoresistive effect principle, and its pressure sensitive element is the diffusion resistance made of integrated circuit technology on the substrate of semiconductor material. When it is subjected to external force, the resistance value of the diffusion resistance changes due to the change of resistivity.                                                                                Strain gauge pressure transmitter

2.4 Field configuration funetion     Basic functions (no password required)   2.5 Precession flowmeter mode setting instructions   1.Gas volume (Gas Qv) A.Measure the working volume as follows Density: Set to 20'℃ density (not involved in the calculation) Pressure: 0.0KPa Temperature:20℃ B.Measure the volume ofthe standard condition as follows; Density: standard condition density (not involved in calculation) Pressure: current pressure (gauge pressure KPa) Temperature:current temperature (degrees Celsius)   2.Gas mass fow(Gas Qm) A. Given the current density, set as follows: (At this time, the state transition coefficient is l) Density: Set to the current actual density Pressure: 0.0KPa Temperature: 20℃ B. Given the density ofthe standard condition, the Settings are as follows: (At this time, the internal state is changedaccording to temperature and pressure) Density: standard condition density (density at 20') Pressure: Current pressure (gauge pressure KPa) Temperature: current temperature (Celsius)   3.Liquid volume (iquid Ov)A,Measure the volume as follows : Density:1.0 or current density (not involved in calculation)   4.Fluid quality (Lieuid Om) A.Set the current density as follows Density:Set to the current actual density   5.Steam volume flow(Steam Ov) Density:1.0 or curent density (not involved in calculation) Pressure:0.0KPa(not involved in operation) Temperature: 20@(not involved in operation) 6.Steam mass flow A.Superheated steam quality(PTSteam(P/T)): If the external temperature or pressure sensor is faulty (or cannot be connected to the temperature or pressure sensor), thevapor density is calculated based on the input temperature or pressure: Pressure: Current gauge pressure KPa Temperature: current temperature ° C B.Saturated steam mass (T)Sat Steam(T)): If the external temperature sensor fails (or cannot be connected to the temperature sensor), the steam density is calculatedaccording to the input temperature; Temperature: Current temperature ° C C.Saturated steam mass (P)(Sat Steam(P)): If the external pressure sensor fails (or cannot be connected to the pressure sensor), the steam density is caleulatedaccording to the input pressure: Pressure: Current gauge pressure KPa   Attached are drawings and schedules 1.Outline dimensional drawing                                                                                              The End  

Difficulties of International Explosion-proof Certification   1. Data: All data must be translated into English, IEC or EN clauses, and each clause must be reasonably explained. The number of rectifications of data during the certification cycle far exceeds the domestic explosion-proof workload. Note: Intrinsically safe products rely on calculation and evaluation, and the workload is cumbersome, which is very different from that in China. There are really few people in China who can calculate and catch up with the foreign level.   2. Testing: Foreign testing is much stricter, and for Class I IECEx certification, personnel from the issuing agency must go to an approved IECEx laboratory for on-site witnessing before testing. 3. Factory audit: There is no need for factory audit in China. Foreign factory audits are based on ISO9001 and then integrated into the EN/ISO/IEC 80079-34:2011 explosion-proof system for on-site review. It is equivalent to redoing a set of explosion-proof systems. And annual audits must be conducted every year after certification.   Note: Without an ISO9001 certificate, you cannot pass the factory audit.     After international explosion-proof practice, the following points are summarized to help you solve your doubts:   1. How long is the international explosion-proof certification cycle?   Answer: Generally 4 to 6 months, this is a perfect situation. Due to uncertain factors such as data and factory inspection, it is common to take 8 to 10 months or longer.   2. Why is the international explosion-proof certification so expensive?   Answer: You also know that it is an international brand. The product certificate is 45,000 RMB (6,600 US dollars), the factory inspection certificate is 45,000 RMB (6,600 US dollars), and the certificate fee is 13,200 US dollars. The daily salary of foreigners is much higher than that in China. Combined with the local level, do you still think it is expensive?   Note: The test fee and witness fee are not listed here because of the different product types and difficulty levels. It is recommended to obtain both ATEX/IECEx certificates to save costs.   3. Why is the certification cycle of famous institutions so slow?   Answer: On the one hand, the communication between China and foreign countries is slow, and on the other hand, it is caused by the laziness of foreigners in developed countries. In the examples I have seen, the certification speed of institutions such as Britain, France, Germany, and the United States is not much faster. Don't compare it with the domestic process.   4. How to improve efficiency for the first international explosion-proof certification?   Answer: Choosing a good certification engineer who understands the process, English, products, standards, testing, and factory inspection will greatly speed up the certification process. Otherwise, it is recommended to find a professional agency or person. Think about it yourself, and you will take more detours than one or two.   Note: This kind of certification engineer is hard to come by, and beginners are advised to find an agent.   5. Is the international factory audit strict?   Answer: There are all the requirements for the factory audit. It depends on the company's system specialists and the degree of cooperation between various departments. The difficulty varies from person to person.   6. Is the certification test conducted abroad?   Answer: At present, the domestic test + foreign certification model is basically adopted.   Note: According to IECEx regulations, the testing location is either in the enterprise itself or in the IECEx laboratory. The former is difficult to achieve due to incomplete equipment, and it is basically the latter. There are about 6 IECEx explosion-proof laboratories in China, and the number is still increasing. After years of development, Chinese people have indeed risen.   7. What is the biggest difference between foreign explosion-proof and domestic ones?   Answer: First, the QAR/QAN system factory audit, second, the involvement of foreigners, and third, the writing of IECEx reports (all in English). EX-TR is indeed very difficult to write, and each item must correspond to product information and test result analysis. A pure explosion-proof product is about 60~70 pages.    

In recent years, with the rapid development of China's explosion-proof technology, more and more domestic explosion-proof companies in various countries have chosen to go abroad and sell their products to countries around the world. For companies, obtaining international explosion-proof certificates is an important process. This chapter briefly introduces international explosion-proof certification agencies.   International Certification Classification   ATEX: Implements EN standards and is commonly used in the EU market.   IECEx: Implements IEC standards and is recognized by IEC system member countries.                                                                                                   1. Openness ATEX: Not open, cannot be queried online, can call the issuing agency. IECEx: Relatively more transparent and open, can be found on the official website. IECEx official website: http://www.iecex.com   2. Mutual recognition ATEX: Cannot transfer Class I certificates required by some special countries. IECEx: Class I certificates of special countries can be converted on this basis. Special Class I certification: US MSHA, Australian ANZEx, Indian DGMS. Note: If you have an IECEx certificate, you only need to do a difference test.   International explosion-proof certification agency   BV/LCIE: Bureau Veritas/French Central Electricity Laboratory Location: Paris, France Founded: 1828 Qualification: Both ATEX and IECEx can be issued Note: BV Group acquired the French LCIE, which actually has the qualification to issue certificates. In Germany, there is also a unit that can issue certificates and belongs to the BV Group     TUV SÜD: TUV SÜD Greater China Group Location: Munich, Germany Founded: 1866 Qualification: ATEX, IECEx can be issued     TUV Rheinland: TUV Rheinland Group Location: Cologne, Germany Founded: 1872 Qualification: ATEX, IECEx can be issued     eurofins: Eurofins Technology Testing Group Location: Italy and Belgium Founded: 1987 Qualification: ATEX, IECEx can be issued     DNV: Det Norske Veritas Location: Oslo, Norway Founded: 1964 Qualification: ATEX, IECEx can be issued     SGS/Baseefa: SGS Standards Technical Services Ltd./British Explosion-proof Electrical Equipment Certification Authority Location: Geneva, Switzerland Founded: 1878 Qualification: Both ATEX and IECEx can be issued Note: SGS Group acquired Baseefa, which actually has the qualification to issue certificates   CSA/sira: Canadian Standards Association/Sira Quality Certification Co., Ltd. Location: Toronto, Canada Founded: 1919 Qualification: Both ATEX and IECEx can be issued Note: CSA Group has acquired Sira, UK, and both parties have the qualification to issue certificates   CQM Fangyuan: China Fangyuan Mark Certification Group Location: Beijing Founded: 1991 Qualification: ATEX, IECEx can be issued Note: Fangyuan currently only has the qualification to issue Class II explosion-proof equipment     CNEX-Global B.V. Location: Arnhem, Netherlands Nature: Invested by CQST, obtained the certification qualification in 2016, and is a Chinese certification agency in disguise. Qualification: Both ATEX and IECEx can be issued     The above is a brief introduction to the commonly used international certification agencies. Of course, there are some well-known agencies that are not listed here, such as: PTB, UL, FM, ITS, FTZU, CCVE, DEKRA, TesfSafe, TUV NORD, CESI, etc.

Selection oftemperature and pressure sampling points: (Figure 8) 1. The temperature sensor (PTl00) is cut a hole (the diameter ofthe hole is 025) after 5D downstream ofthe flow meter, weld the base, and tighten the temperature sensor. 2. The pressure transmiter takes pressure from the suction port (1/4 "NPT') on the lower side ofthe flow meter, Or flowmeter downstream 3 D pressure.   Installation should pay attention to the problem: 1.Note that the flow direction of the arrow on the table body should be consistent with the direction ofthe medium flow. 2.The inner diameter ofthe gasket on both sides ofthe flowmeter shall not be less than the inner diameter ofthe flowmeter! 3.Pay special attention to whether the flange connection flowmeter and the pipeline are aligned; 4.When welding llanges, the flow meter must be removed to avoid excessive welding temperature damage to the sensor probe.   Product wiring Precession flowmeter, output signal is 4-20mA, can display instantaneous flow, cumulative flow, etc., canalso be connected to the computer system and flow display integrator. The terminal board is used to connect external power supplies and output pulses. The power supply voltageranges from 12Vto 32V. Several common wiring methods are listed below: Menu operation 1.Display LCD adopts 128*64 dot matrix display and supports multi-variable display. This meter supports two display modes:【 Three line display mode 】 When the third line is displayed, it is displayed as shown in the following figure:   Other display description:       lf the pressure or temperature sensor is set to "Automatic collection" mode and a sensor failure is detected, the corresponding value is replaced by the "manual" setting value and flashes. The manual setting values here refer to the "gaspressure" and "gas temperature" entered in the menu.      When the flow mode is saturated steam pressure compensation, the temperature sensor is not collected and the temperature value is displayed as---------,indicating that it is not in use.      When the flow mode is saturated steam temperature compensation, the collection of the pressure sensor is not started, and the pressure value is displayed as "--------",indicating that it is not in use.      In the normal display state, you can set the display frequeney, pressure, temperature, density, current, and percentage in the third line by long pressing the M key. The third line shows the variable prompt as follows: 【 Two-line display mode 】 When the third line display is turned off, the second line display is fixed, as shown in the following figure. 2.Detailed description of the field key function 2.1 Deseription ofthe basic functions of keys       This product supports the "three-button" operation mode, The basic functions ofthe three keys are as follows: 2.2 Field configuration entry and exit Enter the field configuration In the "Normal display" state, press the "Z" key to enter the "Live Configuration". The parameters of"FieldConfiguration" can be set by "Direct  digital input" and "Menu selection" Exit the site configuration In the "Field Configuration" state, press the "Z" key to exit the "Field Configuration" and enter the "Display" state. Note: This instrument records the status when the last exit button was set, press "Z" to return to the status when the last exit 2.3 Data setting method  Field setting parameters are divided into two types: "Menu selection" and "Direct digital input". Menu Selection setting method Long press the M key and the underline moves to the second line, indicating that the Settings can be changed. Press the M key to scroll up, or press the S key to scroll down. During the data setting process, hold down the M key to save the Settings. After saving, the underscore is automaticallymoved to the first line; Direet Digital Input setting method) Long press the M key and the underline moves to the second line, indieating that the Settings can be changed.Press the M key to switch symbols. Press the S key to shift to the right, the underscore is moved to the first digit, indicating that it can be modified, short press the M key, and the number is increased by one.Press the $ key again to set the numbers in sequence, and the setting method is exactly the same as the first digit.In the process ofdata setting, long press the M key to save the setting data; Or press Z to exit Settings.For example, the original range limit is 200, and the new range limit is 400, The English menu display is used as an example. Special Version: During the setting process, hold down the M key for three seconds to save and end the data settingDuring the setting process, press the "Z" key to exit the current setting without saving it, Or return to the previous menuAfer setting or exiting the setting, the system stays in the current setting screen.

How does a Coriolis mass flow meter work?   The Coriolis mass flow meter is based on the Coriolis principle. It makes the flow tube through which the medium flows vibrate. The sensor detects and analyzes the changes in the frequency, phase difference and amplitude of the flow tube, directly measures the mass of the medium currently flowing through the flow tube, and calculates the density from the vibration frequency. It can also measure multiple process variables of the pipeline, such as mass flow, volume flow, density, and temperature.   Coriolis Flow Meter vs. Thermal Flow Meter   Coriolis flow meters measure mass flow directly. Direct mass flow measurement reduces inaccuracies caused by fluid properties. Thermal flow meters measure mass flow indirectly. Because of the way they measure, there are fundamental differences between the two devices, and therefore different applications for which each is suitable.   Thermal mass flow meters use the heat capacity of the fluid to measure mass flow. The device is equipped with a heater and 1 or 2 temperature sensors for heating (1 sensor) The power applied or the temperature difference between the 2 sensors is directly proportional to the fluid mass flow rate. Thermal mass flow meters are mainly used for gases.   Because the Coriolis principle directly measures mass flow, Coriolis flow meters can be used for both gases and liquids.   Applications   Coriolis mass flowmeter can be used to measure the mass flow of changing or unknown gas or liquid mixture or to measure supercritical gas. It not only directly measures the mass flow rate without being affected by the physical properties of the fluid, but also has high accuracy and good repeatability. Coriolis flowmeter is a flexible, reliable and accurate flowmeter.

Rotation flowmeter is one of the main flow meter products in the world, widely used in petroleum, chemical.metallurgical and other industrial sectors and municipal construction, environmental protection projects. The flow ofmostliquids, gases and vapors is measured, tested and controlled.Products with the following different functions: l. two-wire rotary flow transmiter: output 4-20mA current signal, while on-site display instantaneous flow, cumulativenow, signal frequency and output current value. lt has the function ofsmall flow cuting and fixed interference sienal eliminating 2. sub-body type: suitable for high temperature, high altitude and other harsh installation occasions. 3. diving type: suitable for easy to be immersed in the environment.     Installation requirements Basic requirements for installation 1 . The flowmeter can be installed indoors or outdoors at an ambient temperature of -30°-+55 ° C 2. when the temperature ofthe measuring medium is higher than l50° C, the meter head can be mounted horizontally orvertically downwards (see Figure 1): Or sorting form (also suitable for high altitude, underground and other bad environment)(seeFigure 2), the maximum extension distanee is lO meters 3.When the measuring medium is liquid and the flow meter is installed in a vertical or inclined pipeline, the liquid fowdireetion should be from the bottom up (see Figure 3 ) 4. In order to facilitate debugging, disassembly and on-site maintenance ofthe flow meter, the clear space above the meterhead is at least 0.5 meters (see Figure 4), if it cannot be guaranteed, the installation Angle should be adjusted during installation.5, The upstream ofthe flow meter should try to avoid the installation of regulating valves and semi-open valves, which canbe installed after $D downstream ofthe flow meter according to the process requirements (see Figure 5).   6. Signal transmission distance: the maximum transmission distance ofcurrent output signal is 800 meters. 7.lfthe precession flow meter is installed in a pipeline with large vibration, it is necessary to install a soft connection pipeor fix the pipe (see Figure 6). 8,.When measuring gas or steam, the precession flow meter should be installed in the high part ofthe pipeline to avoidcondensate in the low part. f the low part is installed at this time, the trap should be installed: When measuring liquid, theflowmeter should be installed at a low place in the pipeline to ensure full pipe measurement. 9.Reserve adequate front and rear straight pipe segments, For the reserved dimensions of straight pipe segments(see Figure 7). Dnstrument nominal caliber, unit mm    

Differential pressure piping installation 1) When the measured flow body is a clean liquid, its pipeline installation diagram (as above) (2) When the measured flow body is corrosive liquid, its pipeline installation diagram (3) When the measured flow body is a clean gas, its pipeline installation diagram (4) When the measured flow body is a corrosive dry gas, its pipeline installation diagram (5) When the measured flow body is water steam, its pipeline installation diagram (6) When the measured flow body is a clean gas, its pipeline installation diagram                                                                                                                    END

  When the fluid filled with pipes flows through the throttling parts (orificles, nozzles, etc.) in the pipes, the fluid will form a local contraction at the throttling parts, so that the flow rate increases and the static pressure decreases, so that the pressure drop or pressure difference is produced before and after the throttling parts, the greater the flow of the medium flow, the greater the pressure difference generated before and after the throttling parts. Therefore, the fluid flow rate can be measured by measuring the differential pressure. Basic installation requirements: (1) The throttling device should be checked before installation whether the number and size of the throttling device meet the requirements of the pipeline installation position. (2) The newly installed pipeline system must be installed after pipeline flushing. (3) When installing the throttling device, pay attention to the direction, and the party with the "ten" number should be installed in the upstream direction. (4) When the throttling device is installed in the pipeline, it should ensure the perpendicularity and concentricity of the pipeline axis. The error of perpendicularity shall not exceed ±10, and the difference of concentricity shall not exceed 0.0025D/0.1+2.3B4. (5) The various sealing gaskets used during installation shall not protrude into the inner wall of the pipeline. (6) The hole plate must be installed at a rate of density, no leakage is allowed, and pressure test should be carried out after installation. (7) The pressure guide pipe should be installed vertically or inclined, and its inclination should not be less than 1:12. For fluids with higher viscosity, the inclination should also increase, and when the pressure signal transmission distance is greater than 3 meters, the pressure guide pipe should be tilted in sections, and a gas collector and a settler should be installed at each highest and lowest point respectively (8) In order to avoid differential pressure signal transmission distortion, positive and negative pressure tubes should be laid as close as possible, and anti-freezing measures should also be taken in cold areas. (9) During installation, attention should also be paid to the position of the pressure opening. When installed on the vertical pipe, the position of the pressure inlet can be selected on the plane of the pressure inlet device: When installed on the horizontal pipe, the position of the pressure inlet is shown in the figure. (Measuring medium picture 1 for liquid, picture 2 for gas)     (10) The minimum pipe section length of the upper and lower reaches of the throttling device: (L1 and L2 are multiples of D).    

Tuning fork liquid level switch is a type of liquid level control switch. The tuning fork is excited by the crystal to generate vibration. When the tuning fork is immersed in liquid, the vibration frequency changes, and the frequency change is detected by the electronic circuit and outputs a switch value.   Principle: The vibration element (tuning fork) vibrates at a certain mechanical resonance frequency under the drive of piezoelectric ceramics. Piezoceramics are mechanically fixed and therefore not limited by temperature shocks. Once the vibrating element comes into contact with the measured medium, the vibration frequency changes. Integral electronics detect this change in vibration frequency and translate it into switching commands. Typical applications are overfill protection and prevention of idling. Due to the simple and robust structure of this instrument, the measurement is hardly affected by the physical and chemical properties of the measured medium. Even if the external vibration is strong or the measured medium is changed, the measurement will not be affected. According to the connection form, the tuning fork level switch can be divided into: flange connection and threaded connection. It is mainly installed on storage tanks, containers, and silos by means of threads and flanges, and measures high, medium and low levels of solid powder or liquid, and achieves the purpose of signal alarm or material level control through the change of vibration frequency. The tuning fork level switch is an indispensable measuring instrument in the raw material storage tank, conveying pipeline and liquid container of the factory. It can be said that as long as a highly reliable tuning fork level switch is installed, the position of the liquid level can be controlled intelligently. In the case of saving a lot of manpower and material resources, it can greatly improve the work efficiency of the factory.   Single machine test of tuning fork level switch wiring: The tuning fork level switch is generally composed of a set of power lines and a set of relay feedback lines. As for connecting normally open contacts or normally closed contacts, it is generally determined by the instrument designer. Each tuning fork level switch is equipped with a set of relay contacts, which are single-pole, double-throw. The relay is only used as a switch and cannot directly drive the alarm or other high-power equipment to act. All control signals are output from the terminal block at the top of the electronic unit. When the green light is on, it indicates that the relay is working normally, and when the light is off, the relay is in an alarm state (when the power is off or the instrument fails, the relay is also in an alarm state).   test: Since the tuning fork level gauge is on/off, there is no need to verify whether it is accurate, just test whether it can work normally. The method is: after the power is turned on, you can hear the vibration of the tuning fork, touch the fork end with your hand, and use the on-off position of the multimeter to measure the switching signal output by the tuning fork corresponding to the touch of your hand. If the medium to be measured is a non-toxic and harmless liquid or solid, you can use a container to sample, then stick the vibrating fork into the medium, use the medium instead of the hand to pinch, and use the on-off gear of the multimeter to measure the on-off signal output by the tuning fork and The touch of the medium corresponds to that.   Case 1 Nuonuo is an excellent instrument worker. Today, I received a notice to repair a tuning fork level switch. It is said that this watch is always falsely alarming and cannot accurately detect the level of the solid silo. Nuonuo reported to me: This watch has been debugged many times, the vibration fork body has been cleaned and put back, and it can be used for a few days. After a few days it failed again, and I don't know how to fix it. Based on the above description, I make the following conclusion: 1. This tuning fork level switch is used to measure solid particles. 2. After the vibrating fork body is wiped clean, it can be put into operation for a period of time. 3. There is a lot of dust in the solid particle silo. In conclusion: Nuonuo and I took the relevant test tools, climbed the ladder to the position of the tuning fork level switch, and tested that its voltage was 23.5V, which was within the allowable error range. When measuring the relay contacts, it will be on and off for a while, which is obviously inconsistent with the actual material level. After removing the vibrating fork body with electricity, it was found that it was covered with a thin layer of solid dust. After wiping the solid dust clean, and then measuring the relay contacts, it is in line with the actual situation. However, doing so can only solve the problem of temporary use, and cannot guarantee that it will be permanently free of problems. This is obviously due to the fact that the measurement accuracy is too high and the sensing element is too sensitive. So I decided to re-tune it, I asked Nuonuo to take some samples and put them next to me, while turning the sensitivity of the tuning fork level switch down, I tested it in the samples. until it is fully adapted to the material.   Case 2 One day Nuonuo told me that the tuning fork level switch of the V-307 residual oil storage tank had been broken for a long time, and I never had a chance to repair it. This time there is no material in the V-307 tank, we can take it down for repair or replacement. in conclusion: I came to this tuning fork liquid level switch with Nuonuo with relevant test tools and tested its voltage at 24.5V, which is within the allowable error range. The contact of the measuring relay is always in a disconnected state, which is obviously inconsistent with the actual material level. Nuonuo immediately took out the watch, and found a dirt similar to coke between the vibrating forks, which prevented the fork from vibrating, and could not be pulled out with tools, so he could only take it to the maintenance room and use steam Heat it to dissolve. After the test is completely normal, it is back to the job.   Case 3 Nuonuo came to the office in the morning and told me that a two-wire tuning fork liquid level switch was newly installed on the V-208 storage tank, and now it is not working properly. The no-load voltage measured on site is 24V, and the on-load measurement voltage is only 9.5V.   In conclusion: Together with Nuonuo, I came to this tuning fork liquid level switch with relevant test tools, and took out a multimeter to measure the voltage, as Nuonuo said. I went to the cabinet room to check that the power supply of this meter is not from the safety barrier, but from the DCS system module. After discussing with the design institute later, this power supply is not suitable, so the construction party is required to add a safety barrier and supply power directly from the safety barrier to this meter.