In the industrial field, radar level meter process connection gasket is a very important accessory, which is mainly used for sealing and isolating the connection between pipelines, valves, pumps and other equipment, in order to prevent media leakage and external impurities from entering the system. In this article, we will introduce in detail the use, classification and importance of process connection gasket in the industrial field.Process connection gaskets are mainly used in the connections between various pipelines, valves, pumps and other equipment, and their role is to provide reliable sealing performance to prevent media leakage and external impurities from entering the system. The use of gaskets can greatly improve the reliability and safety of the equipment, reduce the frequency of maintenance and replacement, reduce the production costs of enterprises.Process connection gasket has a variety of different types, the following are a few of the common classification: process connection gasket according to the material can be divided into metal gaskets, non-metallic gaskets and semi-metallic gaskets. Metal gaskets include stainless steel, copper, aluminium and other metal materials made of gaskets; non-metallic gaskets including rubber, polytetrafluoroethylene (PTFE), asbestos and other materials made of gaskets; semi-metallic gaskets are a combination of metal and non-metallic materials gaskets.Process connection gaskets can be divided into flat gaskets, O-shaped gaskets, winding gaskets and so on according to the shape. Flat gasket is the most common type of gasket, mainly used for flange connection; O-shaped gasket is mainly used for round pipe connection; winding gasket is made of metal and non-metallic tape spiral winding, has good compression and resilience.Process connection gasket according to the use of temperature can be divided into low-temperature gaskets, room temperature gaskets and high-temperature gaskets. Low-temperature gaskets are suitable for low-temperature environments, such as gaskets made of polytetrafluoroethylene; room-temperature gaskets are suitable for room-temperature environments, such as rubber gaskets; high-temperature gaskets are suitable for high-temperature environments, such as high-temperature-resistant asbestos gaskets. Process connection gasket according to the use of pressure can be divided into low-pressure gaskets, medium pressure gaskets and high-pressure gaskets. Low-pressure gaskets are suitable for low-pressure pipeline connections; medium-pressure gaskets are suitable for medium-pressure pipeline connections; high-pressure gaskets are suitable for high-pressure pipeline connections, such as petrochemical pipelines.The role of process connection gaskets is very important in industry.Firstly, it can ensure the normal operation of the equipment, prevent media leakage and external impurities into the system, thus ensuring the stability and safety of production. Secondly, the use of process connection gasket can extend the service life of the equipment, reduce the frequency of maintenance and replacement, reduce the production cost of enterprises. In addition, high-quality gaskets can also improve the sealing performance of the equipment, reduce energy waste, and create more economic benefits for the enterprise.
Temperature transmitter adopts thermocouple, RTD as the temperature measuring element, the output signal from the temperature measuring element is sent to the transmitter module, and then converted into the standard current or voltage signal which is linearly related to the temperature after processing by the circuits of regulator and filtering, arithmetic amplification, nonlinear correction, V/I conversion, constant current and inverse protection, and so on. It is mainly used for the measurement and control of industrial process temperature parameters.Temperature transmitters usually consist of two parts: a measuring unit and a signal processing and conversion unit. Some transmitters add a display unit, and some also have a fieldbus function. As shown in Figure 1.First, the temperature transmitter inspection, test methodsIn the use of temperature transmitters should be regularly on the transmitter inspection and performance testing, temperature transmitter daily inspection items mainly include the contents shown in Table 1. In the daily inspection of the temperature transmitter at the same time, the temperature transmitter should also be measured performance and insulation performance for periodic testing, usually requires a test cycle of no more than 1 year. Temperature transmitter is insulation performance test should be carried out in the case of power failure. Remove the wiring with a 500V megohmmeter to test the transmitter terminals and shell insulation resistance between the resistance should be in line with the requirements of Table 2Temperature transmitter measurement performance inspection can be used in two ways: with sensor test, without sensor test.(1) with sensor test: the transmitter sensing part inserted into the standard temperature source, by changing the standard temperature input, calibration transmitter output current.(2) Without sensor test: Disconnect the transmitter sensing element (RTD, thermocouple), use the standard resistance source and process test equipment, calibrate the signal conversion part of the transmitter alone.Resistance temperature transmitter as an example, such as Figure 2, Figure 3 for the two inspection methods under the calibration equipment connection diagram.In actual use, the temperature transmitter RTDs, thermocouples and other sensing elements of the failure and deviation of the chances of relatively low, the introduction of error is not large, usually can be used without a sensor for temperature transmitter inspection. In demanding places, or the performance of the sensing element and accuracy of the existence of doubt, it is necessary to use the way with the sensor for temperature transmitter inspection. Temperature transmitter measurement performance inspection is for the transmitter measurement error calibration , to determine whether to meet the accuracy requirements.(1) Calibration point selection: the choice of calibration points should be based on the range of the basic uniform distribution, generally should include the upper limit value, lower limit value and range near 50%, including no less than five points.(2) pre-calibration adjustment: in the case of disconnecting the sensor, the input signal with a change in the corresponding output of the lower limit value and the upper limit value of the adjustment, so that it is consistent with the theoretical lower limit value and the upper limit value.(3) Calibration method: when calibrating the transmitter with a sensor, the measurement sequence can start from the lower limit temperature of the measurement range, and then measure sequentially from bottom up, and at each test point, the temperature within the temperature source should be stable enough to be measured; when calibrating the transmitter without a sensor, it should be started from the lower limit by smoothly inputting the signal value corresponding to each calibrated point, reading and recording the output value up to the upper limit, and then reversing the direction. Then change the input signal smoothly to each calibrated point, read and record the output value until the lower limit.(4) Data processing: the principle of data processing in the process of measurement results and error calculation: the number of digits to be retained after the decimal point should be less than 1/10~1/20 of the maximum permissible error of the transmitter for the limit (equivalent to more than the maximum permissible error to take a decimal).Second, the temperature transmitter tuningIn the process of temperature transmitter inspection, if the transmitter is found to exist zero drift, range drift, measurement error over the phenomenon, etc., the transmitter can be adjusted. Intelligent transmitter can use HART hand manipulator for tuning. Temperature transmitter tuning includes: sensor fine-tuning: adjust the factory characteristic curve, so that the transmitter has the best performance in a specific temperature range; analogue output fine-tuning: adjust the analogue output, so that it matches the factory standard or control loop.First, connect the temperature source (analogue RTD, thermocouple source), the hand operated device and digital readout to the transmitter to enable communication between the transmitter and the hand operated device; select a calibration point to apply a standard temperature (RTD, thermocouple) signal; compare the applied temperature with the "Process Variable (PV)" on the Online menu of the hand operated device. Compare the applied temperature with the "Process Variable (PV)" on the operator's Online menu; if the PV reading on the operator does not match the applied standard temperature, fine-tune the sensor; compare the "Analogue Output (AO)" on the operator's Online menu with the reading on the digital readout. If the AO reading on the hand operated device does not match the reading on the digital readout device, the output should be fine tuned.Third, the use and maintenance of the temperature transmitter3.1 Installation of temperature transmitterTemperature transmitter should be installed to ensure that the ambient temperature around: -25 ℃ ~ +70 ℃, try to be installed in the vibration or vibration of small places, the probe inserted into the depth of the best for the medium pipeline diameter of 1/2 ~ 2 / 3. Different types of temperature transmitters should be wired according to their respective instructions, such as two-wire, three-wire and four-wire system, for the safety of explosion-proof requirements for the instrumentation, the wiring of special attention should not be short-circuited. In the intrinsically safe explosion-proof system when using temperature transmitters, pay special attention to the use of matching isolated safety barriers.3.2 Temperature transmitter maintenance and troubleshootingTransmitter in operation should be kept clean, parts and components intact. In principle, it is not allowed to dismantle the transmitter or instrument wiring with electricity, when it needs to be replaced or dismantled, it should be carried out after power failure according to the explosion-proof requirements. Regular checks should be made to verify whether the technical indicators meet the requirements. Typical faults and corrective measures of the temperature transmitter, as shown in Table 3.IV. Concluding remarksTemperature transmitter as the most commonly used temperature measurement instrumentation, its measurement performance not only depends on the factory manufacturing level of the device, at the same time, the use of inspection and testing, effective routine maintenance and reasonable troubleshooting is also an important means to ensure that the equipment long-term precision, effective.
The main plant of the hydropower station is the core area of the hydropower station, in which the measurement and control of the liquid level is crucial for the stable operation of the hydropower station.There are many instruments on the market that can be used to measure the liquid level in the main plant of hydropower station, and radar level meter is one of them, which has been widely used in the measurement of liquid level in the main plant of hydropower station. Today we will introduce the application of radar level meter in hydropower plant level measurement through two actual measurement cases.The level of the main plant of a hydroelectric power station has the following characteristics:The liquid level of the main plant is affected by a variety of factors, such as the incoming water flow, the operating status of the unit, and power generation, which leads to large fluctuations in the liquid level. In order to ensure the normal operation of the hydropower station, the measurement of the liquid level of the main plant must be accurate and reliable, and no error can occur, otherwise it may lead to abnormal operation of the unit, equipment damage and other problems. In order to fully grasp the liquid level of the main plant, it is necessary to set up liquid level meters at multiple locations for monitoring. The internal structure of the main plant is complex, there are many kinds of equipment and pipelines, the installation and commissioning of the liquid level gauge need to fully consider the actual situation on site. As the level gauge in the main plant is in the environment of high humidity, high temperature and strong corrosion for a long time, it needs regular maintenance to ensure its normal operation. (Image source: Internet)Let's look at two cases together, the first one is a hydropower station main plant level measurement requires high accuracy and good stability to ensure the normal operation of the hydropower station. The use of radar level meter for liquid level measurement can overcome the limitations of traditional measurement methods and improve the accuracy and reliability of measurement. Specifically, the radar level meter adopts microwave pulse technology, by transmitting microwave pulses to the liquid surface and receiving the return signal, to achieve accurate measurement of liquid level. In practical application, the radar level meter shows excellent performance, high measurement accuracy, good stability, to meet the requirements of the hydropower station main plant level measurement. The main plant of the second small hydropower station is small in scale, but also requires accurate liquid level measurement. As the level meter adopts the non-contact measurement method, it is not affected by external factors such as medium physical properties, temperature, pressure, etc., so it has a wide range of applications. In practical application, the radar level meter shows the characteristics of high accuracy, high stability and high reliability, which can meet the demand of liquid level measurement in the main plant of small hydropower station. At the same time, the radar level meter also has the advantages of easy installation and convenient maintenance, reducing the cost of use.Radar level meter has a wide range of application prospects in hydropower station main plant level measurement. Through the analysis of actual cases, it can be seen that the radar level meter has the advantages of high precision, good stability, reliability and so on, which can meet the needs of level measurement in the main plant of hydropower stations of different scales. With the continuous development of radar technology, the performance of radar level meter will be further improved, and its application in the level measurement of the main plant of hydropower station will be more widely used. Therefore, for the measurement and control of the liquid level in the main plant of hydropower station, it is recommended that the radar level meter be preferred as the main measuring instrument.
Frequency Modulated Continuous Wave (FMCW) radar level meter has been more and more widely used in municipal, electric power, chemical, petrochemical, metallurgy, food processing and other industries because of its high accuracy, easy installation and maintenance, non-contact and other advantages.The transmitting frequency of the FMCW radar level meter is an equal-amplitude adjustable frequency. By measuring the frequency difference between the transmitting wave and the reflected wave, the frequency difference can be converted into an electrical signal that is proportional to the measured level. A continuous wave radar level meter transmits a continuous microwave signal through a lens antenna, and the frequency of this transmitted signal is linearly modulated by a sawtooth wave. When the continuously emitted microwave signal encounters the surface of the measured medium, part of the energy of the microwave signal is continuously reflected back due to a sudden change in the dielectric constant and is received by the lens antenna system.There is always a difference between the frequency of the received signal and the frequency of the transmitted signal, and this difference is proportional to the distance from the radar antenna to the surface of the measured medium, with a larger frequency difference representing a greater distance to the liquid level.By the formula D = 1/2 × c × (F/R). Where D is the distance from the measuring reference surface to the measured medium; c is the propagation speed of light (electromagnetic wave) in vacuum; F is the frequency difference between the received signal and the emitted signal; R is the rate of change of the emitted signal frequency with time. Then according to the empty liquid level position set by the user, the liquid level height can be calculated by the formula L=E-D. Where E is the measurement reference surface to the user-set empty liquid level position; D is the distance from the measurement reference surface to the measured medium; L is the liquid level height.FM Continuous Wave FMCW Radar Level Gauge features are as follows:(1) High precision, four-wire technology, an alternative to differential pressure, magnetostrictive, radio frequency conductivity, magnetic flap and other level instruments.(2) Less affected by pressure change, vacuum, temperature change, inert gas, smoke, steam and other environmental impact, stable and reliable measurement results.(3) Easy installation, firm and durable, maintenance-free.(4) Sensitive measurement, fast refresh speed.(5) The graphic dot-matrix LCD of the instrument supports complex operations such as on-site waveform display and establishment of false echoes, which reduces the difficulty of instrument operation and maintenance workload.(6) The instrument is preset with Chinese and English menus, which further reduces the difficulty of instrument debugging.