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Low protection level: The valve-specific motor provided by the electrical equipment manufacturer has a fully enclosed squirrel-cage structure, with a short-term intermittent working mode (10 minutes) and self-cooling function. According to GB 4942.1-85 requirements, the minimum protection level is IP44, and the maximum protection level is IP68. The required protection level varies depending on the valve's operating conditions and environment. A low protection level will cause the motor's interior to get damp or for foreign substances such as dust to invade, resulting in a decrease in the insulation resistance and eventual damage. Improper packaging, transportation, and storage: The electrical equipment packaging for the valve should have measures to prevent rain, moisture, and dust. The packaging should be sturdy and reliable. During transportation, there should be measures to prevent rain. After the product arrives at the site, it should be stored in a ventilated and dry place and not be stored outdoors. It is prohibited to conduct debugging or maintenance during rainy weather. After the debugging is completed, all fastening parts should be tightened to ensure that all electrical components are sealed and reliable.  The valve assembly has two important parameters.  The opening and closing torque value should include the actual working torque of the valve plus the torque of the valve itself. The magnitude of the opening and closing torque affects the usage of the valve. A large torque is prone to damage, while a small torque is prone to leakage. There should be sufficient margin in the selection and matching (generally, it is required to be more than 1.1 to 1.3 times the actual operating torque of the valve).  ② The travel position control is related to the valve opening and closing diameter, the duration of opening and closing, and the structural form. The motor used for the valve electrical assembly is a dedicated motor with short-term working cycle, lasting for 10 to 15 minutes. If a high load is applied during the short-term working period, it may cause the motor to overheat, resulting in a decrease in insulation level and potential damage.  The valve electrical assembly does not match the motor model:  The selected motor model does not match the requirements of the electrical equipment. The actual output torque does not leave sufficient corresponding margin, and it is prone to cause damage to the motor during overload operation.  Electrical protection failure, poor quality of electrical components: The microswitches inside the valve electrical assembly are key components of the control mechanism. When the valve exceeds its stroke position, the microswitches cut off the power supply, providing overload protection. Most electrical assembly manufacturers connect stroke and torque protection in series. When the stroke or torque exceeds the limit, the microswitches promptly cut off the AC contactor coil control power, thereby cutting off the main circuit of the motor.  Improper installation and use during debugging:  The valve electrical assembly is divided into two types: horizontal installation and vertical installation. In the vertical installation, the tail end of the motor is at the bottom. When the rubber seal of the wiring sleeve fails, the lubricating oil in the cavity will enter the motor through the cable outlet, which may cause the windings to short circuit and damage the motor.  According to JB 8528-1997, the rotation direction of the handwheel of the electric device should be consistent with the rotation direction of the output shaft. Clockwise rotation is for closing the valve, and counterclockwise rotation is for opening the valve. If the actual rotation direction of the motor does not conform to the specified direction, then any two phases of the three-phase power supply need to be replaced (just by swapping them). Otherwise, due to reverse phase, the protective measures will fail, causing damage to the motor.  ③ Since the dedicated motor for the valve operates under a high-load short-duration working condition, if the continuous debugging time exceeds the rated time, it will cause the motor to overheat and be damaged.  The electrical assembly of the valve does not match the valve connection: The electric assembly of the multi-turn valve is divided into two types: torque type and thrust type. The torque type mostly adopts three-jaw connection or key connection, and the valve assembly does not bear axial thrust. The thrust type mostly uses threaded connection and can withstand large axial thrust. In order to avoid interference between the valve assembly and the valve connection, it is necessary to limit the appropriate gap between the upper part of the valve mating surface and the valve assembly. Ensure that the worm gear installed on the output shaft does not shift axially, ensure that the center meshing plane of the worm and worm gear has a good meshing effect, and ensure that the transmitted torque reaches the rated output torque value.  The temperature control protection system of the motor is malfunctioning.  The motor is equipped with a temperature control switch. When the valve motor is subjected to excessive torque or operates for a long time, the motor temperature rises and exceeds the set temperature value. At this point, the temperature control switch immediately cuts off the control circuit, thereby protecting the motor.

The practice of merely specifying the specifications, categories and working pressure when purchasing valves to meet the procurement requirements is not sufficient in the current market economy environment. This is because valve manufacturers, in order to compete in the market, each conduct different innovations under the unified design concept of the valves, forming their own enterprise standards and product characteristics. Therefore, it is very necessary to propose more detailed technical requirements during the valve procurement process, coordinate with the manufacturers to reach a consensus, and include them as an attachment to the valve procurement contract.  1. General Requirements  1.1 The specifications and categories of the valves should comply with the requirements of the pipeline design documents.  1.2 The model of the valve should indicate the corresponding national standard number it follows. If it is an enterprise standard, the relevant description of the model should be provided.  1.3 The working pressure of the valve should be ≥ the working pressure of the pipeline. Without affecting the price, the working pressure that the valve can withstand should be greater than the actual working pressure of the pipeline; at any side when the valve is closed, it should be able to withstand 1.1 times the valve's working pressure without leakage; when the valve is open, the valve body should be able to withstand twice the valve's working pressure requirement.  1.4 The manufacturing standards for valves should specify the corresponding national standard number. If it is an enterprise standard, the enterprise document should be attached to the purchase contract.  2. Valve Quality Mark  2.1 The material of the valve body should mainly be ductile iron. The brand name and the actual physical and chemical test data of the cast iron should also be specified.  2.2 Valve stem material: We aim to use stainless steel valve stems (2CR13). For large-diameter valves, stainless steel embedded stems should also be used.  2.3 The material of the nuts is cast aluminum brass or cast aluminum bronze, and both the hardness and strength are greater than those of the valve stem.  2.4 The material of the valve stem bushing should have a hardness and strength no greater than that of the valve stem. Moreover, it should not cause electrochemical corrosion with the valve stem and valve body when exposed to water immersion.  2.5 Material of the sealing surface ① The valve types vary, and the sealing methods and material requirements also vary; ② For ordinary wedge gate valves, the material of the copper ring, the fixation method, and the grinding method should all be specified; ③ For soft-sealing gate valves, the physical and chemical as well as hygiene test data of the rubber material used for the valve plate lining; ④ For butterfly valves, the material of the sealing surface on the valve body and the sealing surface on the butterfly plate should be indicated; their physical and chemical test data, especially the hygiene requirements, anti-aging performance, and wear resistance of the rubber; generally, nitrile rubber and ethylene propylene diene monomer rubber are used, and recycled rubber is strictly prohibited.  2.6 Valve Shaft Packing ① Since the valves in the pipeline network are usually not operated frequently, the packing is required to remain inactive and not age over several years, maintaining the sealing effect for a long time; ② The valve shaft packing should also ensure good sealing performance when subjected to frequent opening and closing; ③ Given these requirements, the valve shaft packing is aimed to be replaced for life or not replaced for more than ten years; ④ If the packing needs to be replaced, the valve design should consider measures for replacement under water pressure conditions.  3. Variable-speed transmission box  3.1 The material of the box body and the requirements for internal and external anti-corrosion are consistent with those of the valve body.  3. The box body should have a sealing measure. After assembly, the box can withstand immersion under a water column of 3 meters.  3.3 The opening and closing limit device on the box body should have its adjusting nut either inside the box or outside the box. However, it can only be operated with special tools.  3.4 The transmission structure is well-designed. During opening and closing, it can only cause the valve shaft to rotate without causing it to move up and down. The transmission components fit perfectly, and there is no slippage or disengagement when the valve is opened or closed under load.  3.5 The sealing area between the variable-speed transmission housing and the valve shaft must not be connected as a leak-free unit; otherwise, reliable measures to prevent leakage from occurring should be in place.  3. There should be no debris inside the box. The meshing areas of the gears should be protected by lubricating grease.  4. Operating mechanism of the valve  4.1 When operating the valve, the opening and closing directions should all be clockwise.  4.2 Due to the fact that the valves in the pipeline are often operated manually, the number of times they are opened and closed should not be excessive. Even for large-diameter valves, the opening and closing speed should be within 200 to 600 revolutions.  4.3 To facilitate the manual opening and closing operation by one person, under the working pressure condition of the pipeline, the maximum opening and closing torque should be 240 N-m.  4.4 The opening and closing operation ends of the valves should be square tenons, with standardized dimensions, and should face the ground so that people can operate them directly from the ground level. Valves with a wheel disc are not suitable for underground pipelines.  4.5 Display panel for valve opening and closing degree ① The scale lines for valve opening and closing degree should be cast on the gearbox cover or the outer shell of the display panel after the direction change, all facing the ground. The scale lines should be painted with fluorescent powder to be eye-catching; ② The material of the indicator needle can be stainless steel plate under better management conditions, otherwise it should be painted steel plate. Do not use aluminum sheet for making; ③ The indicator needle should be eye-catching and firmly fixed. Once the opening and closing adjustment is accurate, it should be locked with rivets.  4.6 If the valve is buried at a deep level and the distance from the operating mechanism and display panel to the ground is ≥ 1.5m, an extension rod facility should be provided and firmly fixed to enable people to observe and operate from the ground. That is to say, the opening and closing operation of valves in the pipeline network is not suitable for underground operations.  5. Performance testing of valves  5.1 When manufacturing a certain specification of valves in batches, an authoritative institution should be entrusted to conduct the following performance tests: ① The opening and closing torque of the valve under working pressure; ② The number of consecutive opening and closing operations that can ensure the valve is tightly closed under working pressure; ③ The detection of the flow resistance coefficient of the valve under water transmission conditions in the pipeline.  5.2 Before leaving the factory, the valves should undergo the following tests: ① When the valve is in the open position, the valve body should be subjected to an internal pressure test at twice the working pressure of the valve; ② When the valve is in the closed position, each side should be subjected to 1.1 times the working pressure of the valve without any leakage; however, for metal-sealed butterfly valves, the leakage value should not exceed the relevant requirements.  6. Anti-corrosion treatment of the valve's interior and exterior  6.1 For the valve body (including the transmission box), both the inside and outside should be subjected to shot blasting to remove sand and rust. Then, apply electrostatic spraying of fine powder-free toxic epoxy resin with a thickness of more than 0.3mm. If it is difficult to conduct electrostatic spraying on extremely large valves, similar non-toxic epoxy paint should be brushed or sprayed instead.  6.2 The interior of the valve body and all parts of the valve plate must be fully protected against corrosion. Firstly, they will not rust even when immersed in water, and there will be no electrochemical corrosion between the two metals. Secondly, the smooth surface reduces the resistance of water flow.  6.3 The hygiene requirements for the epoxy resin or paint used for the anti-corrosion treatment of the valve body must be based on the test reports issued by relevant authoritative institutions. The chemical and physical properties should also comply with the specified requirements.  7. Valve packaging and transportation  7.1 Lightweight blocking plates should be installed on both sides of the valve for sealing.  7.2 For medium and small-sized valves, they should be tied with straw ropes and transported in container form.  7.3 For large-diameter valves, there is also a simple wooden frame for solid packaging to prevent damage during transportation.  8. Factory manual of the valve. As a piece of equipment, the following relevant data should be indicated in the factory manual of the valve: valve specification; model; working pressure; manufacturing standard; valve body material; valve stem material; sealing material; valve shaft packing material; valve stem sleeve material; internal and external anti-corrosion material; operation and start direction; rotation speed; opening and closing torque under working pressure conditions; manufacturer's name; date of manufacture; factory serial number; weight; diameter, number of holes, and center hole distance of the connecting flange; indicate the control dimensions of the overall length, width, and height in a graphical manner; valve flow resistance coefficient; effective opening and closing times; relevant data of valve factory inspection and installation and maintenance precautions, etc.

The pneumatic valve positioner operates based on the principle of torque balance. When the signal pressure P1 introduced into the bellows 2 increases, the main lever 3 rotates around the fulcrum, causing the nozzle baffle 9 to approach the nozzle. The back pressure of the nozzle is amplified by the unidirectional amplifier 8, and the pressure introduced into the diaphragm chamber of the actuator increases, causing the valve stem to move downward. It drives the feedback rod to rotate around the fulcrum, and the feedback CAM also rotates counterclockwise. Through the roller, the secondary lever 4 rotates around the fulcrum and stretches the feedback spring. When the pulling force of the spring on the main lever 3 and the force of the signal pressure applied to the bellows reach torque balance, the instrument reaches a balanced state. The valve position of the actuator is maintained at a certain opening degree, and a certain signal pressure corresponds to a certain valve position opening degree. The above mode of action is positive action. If you want to change the mode of action, just flip the CAM to change the A direction to the B direction, etc. The so-called positive action positioner means that when the signal pressure increases, the output pressure also increases. The so-called reaction positioner is one where the output pressure decreases as the signal pressure increases. As long as a direct-acting actuator is equipped with a reverse-acting positioner, it can achieve the action of a reverse-acting actuator. On the contrary, a reaction actuator can perform the actions of a positive actuator as long as it is equipped with a reaction positioner.

【Changshu Valve Positioner】Prospects for the Internet Development in the Valve Industry   The international internet, also known as the Internet, is a global network that connects netizens worldwide through thin cables. On the internet, you can access almost any information you need, all of which is freely available. It maximizes the utilization of all data resources and exists in various forms. As a result, the internet is increasingly transforming how people learn, work, and live, even influencing the entire social process.  The valve industry, on the other hand, is a traditional sector. As an indispensable component of fluid control equipment and large-scale complete sets of equipment in various sectors of the national economy, it plays a crucial role in every position.  So, what is the connection between these two distinct industries?  As the internet continues to grow, all traditional industries inevitably face varying degrees of impact from this new phenomenon, including the valve industry. Under this wave of change, some industries have faltered, while many others have seized new opportunities like bamboo shoots after rain. We have embarked on the path of internet development. Online, all information resources transcend geographical limitations, and with today's highly developed logistics, even partners separated by thousands of miles can collaborate seamlessly.  Valves are widely used in industries such as petrochemicals, oil refining, nuclear power, and thermal power. Beyond these, the construction industry and other specialized sectors also rely on valves. The extensive applications of valves across numerous enterprises highlight the industry's rapid growth and promising prospects. Moreover, in the next decade, major projects such as thermal power, nuclear power, hydropower, large-scale petrochemical plants, oil and gas pipelines, coal liquefaction, and metallurgy will experience unprecedented development. Consequently, new valve products tailored to these projects will become a focal point of innovation, driving rapid growth in the entire valve market. Additionally, general valve products are simple to manufacture, in high demand, and face fierce global competition. From a market perspective, the valve industry is relatively concentrated but has yet to form a monopoly. Given the internet's immediacy and cross-regional nature, the industry's future looks bright.

Filters, pressure reducing valves, and lubricators together form the pneumatic trio. The filter is mainly responsible for filtering liquid water, oil, and impurities from compressed air. The pressure reducing valve is primarily used to control system pressure, while the lubricator is responsible for supplying oil lubrication to downstream components. Generally, lubricators are not used much nowadays because many products can achieve oil-free lubrication, eliminating the need for lubricators. The function of a compressed air filter: to remove solid impurities, water droplets, and oil droplets from compressed air, but it cannot remove gaseous oil and water.Based on the drainage method of the filter, there are manual drainage types. Automatic drainage types can be further categorized into normally open and normally closed types based on their drainage state when there is no air pressure.The function of a pressure reducing valve: A pressure reducing valve is an intelligent valve that uses the medium's own energy to regulate and control pipeline pressure. By adjusting the pilot valve of the pressure reducing valve, the outlet pressure of the main valve can be regulated. The outlet pressure remains unaffected by changes in inlet pressure or inlet flow, reliably maintaining the set outlet pressure. The set value can be adjusted as needed to achieve the purpose of pressure reduction.Basic performance of pressure reducing valves:(1) Pressure regulation range: This refers to the adjustable range of the output pressure P2 of the pressure reducing valve, within which the specified accuracy must be achieved. The pressure regulation range is mainly related to the stiffness of the pressure regulating spring.(2) Pressure characteristics: This refers to the characteristic where, at a constant flow rate g, output pressure fluctuations occur due to input pressure fluctuations. The smaller the output pressure fluctuations, the better the performance of the pressure reducing valve. The output pressure must be below the input pressure by a certain value to remain largely unaffected by changes in input pressure.(3) Flow characteristics: This refers to the characteristic where, at a constant input pressure, the output pressure changes with variations in output flow g. The smaller the change in output pressure when flow g varies, the better. Generally, the lower the output pressure, the smaller the fluctuations caused by changes in output flow.

The entire control loop is regulated by a two-wire, 4-20mA signal. The HART module transmits and receives digital information superimposed on the 4-20mA signal, enabling bidirectional digital communication with the microprocessor. The analog 4-20mA signal is transmitted to the microprocessor, where it is compared with feedback from the valve position sensor. The microprocessor performs control calculations (primary control) based on the magnitude and direction of the deviation, issuing electrical control commands to the piezoelectric valve to initiate opening or closing actions. The piezoelectric valve adjusts the output pressure increment of the pneumatic amplifier according to the pulse width of the control command, while the output of the pneumatic amplifier is fed back to the internal control loop. This feedback is again compared and processed with the microprocessor's computational results (secondary control), generating a two-stage control output signal to the actuator. Changes in air pressure within the actuator regulate the valve stroke. When the control deviation is large, the piezoelectric valve emits a wide pulse signal, causing the positioner to output a continuous signal that significantly alters the signal pressure to the actuator, driving rapid valve movement. As the valve approaches the desired position, the difference between the commanded position and the measured position decreases, prompting the piezoelectric valve to output narrower pulse signals. These intermittent, minor adjustments to the actuator's signal pressure allow the actuator to approach the new commanded position smoothly. When the valve reaches the target position (entering the dead zone), the piezoelectric valve ceases pulse output, and the positioner's output remains zero, stabilizing the valve in place.

 【 Changshu Valve Positioner 】 Key project construction in the valve industry helps the valve industry to embark on a fast track of sound and rapid development    The valve industry is a traditional advantageous industry in our country. To make traditional industries stronger and larger, China has adopted proactive and flexible measures to accelerate the development of the valve industry and promote it to become the backbone supporting the development of China's industrial economy. On the one hand, China vigorously implements a project-driven strategy, prioritizing valve industry projects in municipal key projects and actively striving for provincial key projects. It also intensifies project coordination efforts, designates specific personnel, and implements dedicated responsibilities to actively assist project units in fulfilling construction conditions. On the other hand, the overall arrangement for accelerating industrial structure adjustment has been made. We actively organize and guide enterprises within the Second Ring Road to relocate and transform, and vigorously promote the optimization and upgrading of the industrial structure. We pay attention to using independent innovation and technology introduction to transform traditional manufacturing industries, promote technological improvement of enterprises, continuously expand the space for economic growth, and through various measures, have greatly advanced the construction of valve industry projects.    It was recently learned from the Municipal Development and Reform Commission that through the implementation of key projects, the development potential of China's valve industry is growing increasingly strong. Currently, there are 13 ongoing valve industry projects in the city, with a total investment of 3.26 billion yuan.   In accordance with the needs of industrial structure adjustment, re-layout should be carried out. Through the relocation of industries into industrial parks, enterprises should be relocated and transformed to make the valve industry bigger and stronger. Among the 13 ongoing projects this year, 6 are overall relocation projects. The overall renovation and relocation project of Hebei Electric Motor Co., Ltd. has a total investment of 190 million yuan, with an annual motor production capacity of 9 million kilowatts. It is expected to achieve sales revenue of 1.2 billion yuan, profits and taxes of 180 million yuan, and an export volume of 50 million US dollars. The project will be completed and put into operation by the end of the year. The overall renovation and relocation project of Shijiazhuang Qiangda Pump Industry Group has a total investment of 460 million yuan and is expected to achieve sales revenue of 660 million yuan and profits and taxes of 110 million yuan. The project has been completed and put into operation recently. The overall renovation and relocation project of Shijiazhuang Jingang Group, with a total investment of 290 million yuan, is expected to produce 41.5 million internal combustion engine parts annually and achieve sales revenue of 420 million yuan. The project has recently entered the trial production stage.   The overall renovation and relocation project of Hebei Taihang Machinery Factory, which has been completed and put into operation in the first phase, has a total investment of 510 million yuan. It is expected to produce 1,000 FA series roving frames, 1,000 carding frames, 2,000 fine frames and 1 million rollers annually, with an estimated sales revenue of 1.36 billion yuan. Currently, the project is in the process of accelerating the construction of the second phase. In addition, there is the relocation and expansion project of castings and metallurgical equipment of Shijiazhuang Sanhuan Valve Co., LTD., with a total investment of 209.82 million yuan. The overall relocation project of the municipal submersible electric pump factory has a total investment of 114.39 million yuan.    Among the current planning and early-stage projects, there are still a number of key projects in the valve industry. Through continuous efforts, China's valve industry is bound to enter a fast lane of sound and rapid development.

【Changshu Valve Positioner】Exploring the Potential of the Valve Industry   Improving the quality and grade of valve products is the primary issue to be addressed for the future development of China's valve industry. The overall downturn in the valve industry has led to the backwardness of domestic valve products, which is a major factor restricting their development. Previously, in the government-led "West-East Gas Pipeline" project, many local valve enterprises missed the opportunity. In addition to macroeconomic factors, other constraints such as outdated equipment and technology, low specialization, and small market size also act as bottlenecks for the industry's growth.  For the domestic valve industry, there is a significant gap between inland and coastal regions. The inland valve industry has a lower starting point, smaller scale, lower specialization, and less marketization, widening the disparity with coastal areas and contributing to the unbalanced development of the industry nationwide.  To break free from the current predicament and overcome these bottlenecks, the domestic valve industry must seek new growth opportunities by introducing advanced foreign equipment and technology to strengthen its capabilities. To secure a firm position in the fierce competition, corresponding measures must be taken. It is reported that foreign capital will gradually enter China's valve industry in the near future, which will undoubtedly serve as a strong stimulus for domestic players.  The growth and expansion of the valve industry rely heavily on the contribution of highly skilled professionals. We must learn to allocate and utilize talent scientifically, ensuring that "resources are fully utilized and talents are maximized," while also emphasizing talent development. The industry's progress depends on human resources, and maintaining a stable and sharp workforce is a critical consideration for every business operator. The advancement of the era and technology is marked by innovation—only continuous innovation can sustain the industry's competitiveness, keep it ahead, and pave the way for a brighter future.  With the progress and development of science and technology, as well as the accelerating pace of socioeconomic growth, competition in the valve industry is becoming increasingly intense. China's valve industry is now moving toward higher levels of automation, intelligence, multifunctionality, efficiency, and lower consumption.  To achieve greater progress, the valve industry must strictly ensure product quality, focus on the improvement and innovation of valve manufacturing processes, and produce products that truly meet customer needs. As valve manufacturers, it is essential to listen more, think more, and delve into the frontline to understand customers' real demands. A thorough analysis of product shortcomings and proactive problem-solving will lay the groundwork for long-term corporate development.

A valve positioner is a critical accessory for pneumatic control valves, operating primarily based on the force balance principle and the displacement balance principle. Below are the two common working principles and their detailed descriptions: 1. **Force Balance Principle**   **Structural Components:** Mainly consists of a measuring element, amplifier, feedback element, and setpoint component. The measuring element is typically a displacement sensor used to detect the actual position of the valve; the amplifier boosts weak electrical or pneumatic signals to drive the actuator; the feedback element sends the valve's actual position signal back to the positioner; and the setpoint component sets the desired valve position based on the control signal.   **Working Process:** When the control system provides a setpoint signal, this signal is compared in the positioner with the actual valve position signal fed back by the feedback element, generating an error signal. This error signal is amplified by the amplifier, which then outputs a corresponding control signal to the actuator of the pneumatic control valve, causing the actuator to move and thereby drive the valve. As the valve moves, the feedback element continuously sends the actual valve position signal back to the positioner, which again compares the setpoint signal with the feedback signal, adjusting the output control signal until the actual valve position matches the setpoint, the error signal becomes zero, and the valve stabilizes at the set position.2. **Displacement Balance Principle**   **Structural Components:** Primarily includes a nozzle-flapper mechanism, pneumatic amplifier, feedback cam, and spring. The nozzle-flapper mechanism is the key part for converting displacement into a pneumatic signal; the pneumatic amplifier boosts the pneumatic signal; the feedback cam transforms the valve's displacement into a feedback force; and the spring provides reset force and balancing action.   **Working Process:** When the input signal changes, it causes the flapper in the nozzle-flapper mechanism to move. The flapper's displacement alters the gap between the nozzle and flapper, thereby changing the nozzle's backpressure. This backpressure change is amplified by the pneumatic amplifier, which then outputs a pneumatic signal to the actuator of the pneumatic control valve, driving the valve to move. As the valve moves, the feedback cam converts the valve's displacement into a feedback force. The feedback force interacts with the spring force, and when equilibrium is reached, the flapper returns to its initial position, stabilizing the nozzle's backpressure. The pneumatic amplifier's output signal also stabilizes, and the valve remains fixed at the new position.   In practical applications, valve positioners also offer various functions, such as enabling rapid valve positioning, improving control accuracy, enhancing flow characteristics, and achieving split-range control, thereby better meeting the control requirements of industrial processes.

【Changshu Valve Positioner】Instructions for Using Level Transmitters The level transmitter is based on the proportional relationship between pressure and liquid height, utilizing isolated diffused silicon sensors or advanced ceramic capacitive pressure sensors. It converts pressure into electrical signals, which after temperature compensation and linear correction, become standard electrical signals for liquid level measurement. Suitable for various media systems in petrochemical, power, metallurgical, pharmaceutical, water supply/drainage, and environmental protection industries. Its compact structure provides users with convenient, simple adjustment and flexible installation. Standard output signals are available for user selection as needed.Working Principle of Level Transmitters:When measuring liquid depth, the level transmitter's pressure sensor receives hydrostatic pressure proportional to the liquid density and local gravitational acceleration. The liquid pressure is transmitted through a stainless steel gas-guiding tube to the sensor's positive pressure chamber, while the negative pressure chamber connects to the liquid surface atmosphere. This differential pressure measurement allows precise determination of liquid depth.Product Features:- Excellent stability with long-term zero/span stability- Wide operating temperature range- Reverse polarity protection and overcurrent protection circuits- No damage from incorrect installation polarity- Automatic current limiting during abnormal conditions