2022.03.09
Electric Actuated Needle Valve and Electronic Air Pressure Regulator
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Abstract: This article mainly introduces the work in localized substitution. The substitute product is Emerson TESCOM ER5000 series electronic pressure regulator and its back pressure valve. Also introduce the features and deficiencies of KaoLu’s electric actuated needle valve, putting forward the technical route, describing performance indicators, and introducing the functional expansion and technological innovation. We can see that localized substitute products have more advantages, low cost high performance and flexibility of use.
1. Emerson ER5000 series electronic pressure regulator 1.1. Structure and principle of electronic pressure regulator
Emerson's latest TESCOM ER5000 series electronic pressure regulator is a multifunctional integrated electronic pressure regulator that integrates three components: pressure sensor, PID (proportional-integral-derivative) controller and electric actuated needle valve. It is integrated with electric actuated needle valve to form a complete control mechanism. TESCOM ER5000 electronic pressure regulator and its basic structure are shown in Figure 1-1.
From Figure 1-1, we can see that function of ER5000 electronic pressure regulator is to control pressure at bottom outlet, reducing intake pressure and control it to the set pressure, so that the pressure at the bottom outlet is always consistent with the set pressure.
ER5000 electronic pressure regulator is actually an electronic pressure reducing valve, its working principle is shown in Figure 1-2.
External air source supplies pressure to ER5000, and supply pressure becomes the output pressure at outlet through opened intake valve, and this output pressure feeds back to the PID controller through the pressure sensor. If the feedback value is lower than pressure set value, the controller continues to control intake valve to open it until feedback value equals set value. When the above two values are equal, the intake valve will close, and the outlet will continue to output a constant set point pressure. If feedback value is higher than set value, the controller will actuate an exhaust valve, thereby exhausting the excess outlet pressure until feedback signal equals the set value. When the above two values are equal, the exhaust valve will close, and outlet will also continue to output a constant set point pressure.
Figure1-2 TESCOM ER500 electronic pressure regulator schematic diagram
1.2. Typical applications
ER5000 pressure controller mainly has two applied directions, one is single machine application, and the other is application work with other special valves to achieve pressure regulation and control in different ranges. (1) Single machine application: It can be seen from above structure and principle that TESCOM ER5000 electronic pressure controller is a very typical electronic pressure reducing valve. In the case of single machine use, the controller itself can reduce pressure and accurately control the gas source with pressure below 8.2bar, and even control the wide vacuum. In addition, in single machine application, it can respectively use two control modes, internal and external feedback. It shows in Figure 1-3 and Figure 1-4.
(2) Use in conjunction: An important application of ER5000 electronic pressure regulator is to use it as a pilot valve in conjunction with other regulating valves to regulate a wider pressure range. Greater pressure relief applications are shown in Figure 1-5, and are used in conjunction with a back pressure valve in Figure 1-6.
1.3. Performance indicators
Since TESCOM ER5000 series electronic pressure regulator is an integration of three parts: pressure sensor, PID controller and two-way pressure regulating valve, the technical indicators of each part represent the overall performance of the controller, and the relevant technical indicators and functions are listed as follows:
(1) Pressure control principle: double solenoid valve three-way pressure control.
(2) Medium type: clean, dry inert gas or instrument-grade air.
(3) Air intake pressure (absolute pressure): minimum (vacuum pump pressure), maximum 8.2bar (820kPa)
(4) Air outlet pressure (absolute pressure): minimum 0.07bar (7kPa), maximum 8.2bar (820kPa)
(5) Input signal: USB, RS485, 4~20mA, 1~5V or 0~10V.
(6) External sensor feedback signal: 4~20mA, 1~5V or 0~10V.
(7) Measurement accuracy of internal pressure sensor: ±0.10% (FSO), including ±0.05% (FSO) linearity and ±0.05% (FSO) hysteresis.
(8) Controller A/D conversion: 16 bits.
(9) Controller repeatability: ±0.05% (FSO).
(10) Controller resolution sensitivity: ±0.03% (FSO).
(11) Control mode: PID (combined with the special software ERTune for PID parameter debugging and optimization).
(12) Control mode: internal feedback, external feedback and double loop.
We will focus on three control modes of ER5000 electronic pressure regulator which is a technical highlight of it:
(1) Internal feedback mode: This mode only uses internal sensors. The internal feedback mode uses ER5000 internal pressure sensor to monitor absolute pressure inside the controller in range of 1~100psig/0.07~6.9bar.
(2) External feedback mode: This mode only uses external sensors. External Feedback mode utilizes a user-supplied external sensor to monitor system pressure, which is installed in pipe line and provides direct feedback to ER5000.
(3) Dual loop mode: This mode uses both internal and external sensors in a "loop-in-loop" layout. Dual loop mode executes one PID loop within another PID loop. The inner circuit uses controller's internal sensor, and the outer circuit uses external sensor.
1.4. Functions and Features
From the above introduction, the following functions and features of the ER5000 electronic pressure regulator can be summarized:
(1) The main function of ER5000 electronic pressure regulator is to control gas pressure (not flow), which can reach accurate control of pressure in sealed containers and pipelines.
(2) The overall integrated structure integrates pressure sensor, PID controller and two-way pressure regulating valve, making the overall structure small and easy to install and use in parallel with multiple units.
(3) As a typical electronic pressure regulator, it can directly reduce the air source pressure with a maximum of 8.2bar and control it accurately and constant pressure (air intake is positive pressure), and can also be used to control low pressure (wide vacuum, air intake is vacuum), and minimum pressure can reach 0.07bar (7kPa).
(4) The ER5000 electronic pressure regulator can be used as a pilot valve to drive various large-scale pressure reducing valves and back pressure valves. The outlet of controller is connected to pilot ports of other back pressure valves to realize pressure regulation and control in a larger range.
(5) The measurement accuracy of pressure sensor is ±0.1% and the 16-bit A/D conversion is a medium and high-end technical index, which can meet most applications.
(6) The digital PID control mode can reach fast speed and accurate control of pressure.
(7) Three control modes of internal feedback, external feedback and dual loop make ER5000 electronic pressure regulator have greater flexibility in use, and the best control mode can be selected according to actual use requirements.
1.5. Insufficiency of pressure controller
Although ER5000 electronic pressure regulator has many function and features mentioned above, it still has the following limitations and deficiencies in practical applications.
(1) The ER5000 electronic pressure regulator integrates three most common components in the field of vacuum pressure control; due to it is an integrated structure rather than a modular design structure. This limits application of ER5000 electronic pressure regulator. For example, ER5000 electronic pressure regulator integrates two solenoid valves, but it can only control gas pressure, but can’t control gas flow that only requires a single solenoid valve.
(2) The ER5000 electronic pressure regulator focuses more on positive pressure control, and can also work partial negative pressure control. This is mainly due to the high leak rate of valve used, so sensor (especially external sensor) and PID are not used power of control. If gas leakage rate of valve inside the controller can be reduced, the controller can completely cover the control of entire vacuum degree range, extending the current vacuum degree of 7kPa to about 1Pa.
(3) In application of driving various large-range pressure reducing valves and back pressure valves, the use of higher-priced ER5000 electronic pressure regulator as pilot valve has a very low cost performance, and electric actuated needle valve can be used.
(4) The 16-bit A/D conversion of ER5000 electronic pressure regulator is a medium and high-end technical index. If an external high-precision pressure sensor is used, a 24-bit A/D converter is required, which makes ER5000 electronic pressure regulator unable to meet some requirements in occasions that require high measurement and control accuracy.
(5) The on-site operation is very complicated. Although ER5000 electronic pressure regulator adopts PID control method, the adjustment of PID parameters requires the use of special software. The controller itself lacks PID parameter self-tuning function, and needs to be connected to a computer. (6) The ER5000 electronic pressure regulator itself lacks the display function, and it needs to connect to the computer and use the supporting software to debug and display the control process and results. (7) The overall price of ER5000 electronic pressure regulator is high, and the operation is complicated, which has higher requirements for operators. Combined with above-mentioned deficiencies of controller, this makes ER5000 electronic pressure regulator not cost-effective, and it is obviously very extravagant and wasteful to use in many occasions.
2. Localized alternative technology route
For localized replacement of Emerson's latest generation TESCOM ER5000 series electronic pressure regulator, the technical route is to first realize the measurement and control function of ER5000 electronic pressure regulator, and provide a cost-effective domestic electronic pressure regulator. Then, the module structure technology route is adopted to separate the vacuum pressure sensor, PID controller and electronic valve into their own independent modules. Each type of module is composed of a series of components with different technical indicators. Through the combination of these modules with different performance indicators, different control functions and precision requirements can be realized, and the controller functions can be expanded to meet different needs and have low cost high performance.
2.1. To reach the function of ER5000 electronic pressure regulator
(1) Localized substitute products must achieve most functions of ER5000 electronic pressure controller, that is, to realize reducing pressure and pressure control functions of ER5000 electronic pressure regulator itself.
(2) Localized substitute products, like ER5000 pressure controller, can act as a pilot valve to reduce pressure and control gas with a large range and high pressure range.
(3) Localized substitute products have the function of setting value input and display, and do not need software and connection to a computer for operation.
(4) The price of localized substitute products is low and cost-effective.
2.2. Modular structure and function expansion
(1) Modular structure is divided into three modules: sensor, PID controller and electronic valve.
(2) PID controller module is the core device of all modules which determines the measurement and control accuracy, the types of sensors and electronic valves that can be used together, the control method and control mode. PID controller module will use a 24-bit A/D converter to improve measurement and control accuracy, integrate two independent control channels. It can control 2 vacuum pressures or 1 vacuum pressure and 1 temperature at the same time. Also, it can connect a variety of vacuum pressure and temperature sensors. The combination of 2 channels can perform forward and reverse bidirectional control to meet the upstream and downstream control modes of vacuum pressure. It can have dual sensor automatic switching function to cover a wide range of measurement and control. The PID controller with program setting function can input multiple control process curves. Multiple groups of PID parameters can be input and stored, the PID parameter adjustment has self-tuning function, and the controller has a color LCD screen to display the entire process parameters and results.
3. Localized alternative products
According to above-mentioned localization alternative technical route, KaoLu has developed corresponding products, electric actuated needle valve.
3.1. Digital pressure regulator
The locally produced digital display pressure regulator includes positive pressure type and vacuum type. The pressure control principle and basic structure are the same as those of Emerson TESCOM ER5000 series electronic pressure regulator, as shown in Figure 3-1.
Please visit https://www.genndih.com/proportional-pressure-regulator.htm
The local electronic pressure regulator is also an integrated structure of three parts: a pressure sensor, a controller and a two-way pressure regulating valve. The relevant technical indicators and functions are listed as follows:
(1) Pressure control principle: double solenoid valve three-way pressure control.
(2) Medium type: clean, dry inert gas or instrument-grade air.
(3) Air intake pressure (absolute pressure): minimum (vacuum pump pressure), maximum 50bar (5MPa)
(4) Air outlet pressure (absolute pressure): minimum 0.21bar (21kPa), maximum 30bar (3M Pa)
(5) Input signal: 4~20mA, 0~5V or 0~10V.
(6) External sensor feedback signal: 4~20mA, 0~5V or 0~10V.
(7) Measurement accuracy of internal pressure sensor: ±1.0% (FSO), including ±0.5% (FSO) linearity and ±0.5% (FSO) hysteresis.
(8) Controller A/D conversion: 12 bits.
(9) Controller repeatability: ±0.5% (FSO).
(10) Controller resolution sensitivity: ±0.2% (FSO).
(11) Control method: Built-in PID automatic control, without manual intervention.
(12) Control mode: internal feedback and external feedback. It can be seen that some technical indicators of localized pressure controller have been reduced, such as 12-bit A/D conversion and ±1.0% measurement accuracy, but the use of pressure range has been expanded, also display and input functions have been added. The pressure controller can be used independently without external computer and software debugging which reduces the difficulty of operation, improves low cost high performance, and can basically meet the application in most fields.
3.2. Back pressure valve (high pressure type and vacuum type)
The locally produced new back pressure valve modules are separately divided into high pressure type and vacuum type back pressure valves. Both back pressure valves use the above digital display pressure controller as a pilot valve for control, but the new back pressure valve is not suitable for traditional back pressure valves such as Emerson TESCOM. Significant improvement has been made to the pressure valve. The traditional back pressure valve has a valve seat fixed on the valve body, and valve seat is tightly fitted with valve core to achieve sealing effect. It provides basic pressure control for most simple processes. In this design, a spring or other means provides a preset loading force that seals valve plug against valve seat. When the force of pipeline pressure acting on spool is the same as loading force, the back pressure valve works normally under preset pressure state; when pressure at the inlet end of valve increases, the force acting on spool exceeds At the preset loading force, valve core and valve seat are separated, releasing excess pressure at inlet end until preset pressure is restored. In the traditional back pressure valve structure, when instantaneous flow rate changes greatly or inlet pressure fluctuates frequently, the control pressure accuracy is low. Reasons are as follows:
(1) Since most traditional back pressure valves with a control pressure exceeding 20bar use a piston as load mechanism for spool. O-ring in piston increases friction which makes the spool act stuck.
(2) The inlet and outlet flow passages of traditional back pressure valves are mostly single passages with a fixed cross-sectional area. When flow rate at inlet of valve increases or decreases rapidly, the CV value (flow capacity) of valve does not change, it will make the inlet pressure fluctuates violently. (3) The valve core and valve seat of traditional back pressure valve, due to the need for sealing, there is stress or friction when fitting and frequent opening and closing. This will cause them to wear and consume each other, destroy the initial shape, and change CV value unpredictably. The new type of back pressure valve is a bonnet and valve body structure connected from top to bottom, as shown in Figure 3-2. A diaphragm is connected between valve cover and valve body. A pilot air hole is provided on the top of valve cover. The pilot air hole is connected to movable groove opened at the bottom of valve cover for undulating movement of the middle of diaphragm through the air source channel opened inside the valve cover, forming an up and down connection. On the side wall of valve body, there are respectively oppositely arranged medium inlet and medium outlet, medium inlet is connected with a plurality of inlet holes opened on the upper surface of valve body, and the medium outlet is connected with a plurality of outlet holes opened on the upper surface of valve body. The outstanding features of new back pressure valve are that the entire action is frictionless. Also, it does not produce pressure lag, has high inlet pressure stability and greater flow capacity.
3.3. Two-way high-precision PID controller
For PID control module, in order to meet a wide range of vacuum pressure control requirements, KaoLu has produced VPC2021 series PID controllers, which can measure, display and control vacuum, pressure and temperature. Using 24-bit data acquisition and artificial intelligence PID control technology, it can be connected to various types of vacuum, pressure and temperature sensors, and can control various types of electric needle valves, electric valves and heaters and other executive structures. It can also achieve high-precision vacuum. The fixed-point and program control of parameters such as pressure and temperature is a high-performance and cost-effective controller that replaces foreign high-end controller products.
As shown in Figure 3-3, VPC2021 series PID controller has two-way independent measurement and control function which can measure, display and control parameters on different channels at the same time. If two channels are connected to sensors of the same type but different ranges, as shown in Figure 3-4, automatic switching between two sensors can be reached according to test value, thus covering a wide range of measurement and control.
The main technical indicators of VPC2021 series dual-channel high-precision PID controller are as follows:
(1) Measurement accuracy: ±0.05%FS (24-bit A/D).
(2) Input signal: Can be connected to many vacuum pressure sensors, 32 signal input types (voltage, current, thermocouple, thermal resistance).
(3) Control output: 4 types of control output (analog signal, solid state relay, relay, SCR), which can be connected to many electric regulating valves.
(4) Control algorithm: PID control and self-tuning (20 groups of PID parameters can be stored and recalled).
(5) Control mode: fixed-point and program control, can support up to 9 control curves, each of which can be set with 24 program curves.
(6) Channel: dual channel, dual channel sensor switches automatically.
(7) Communication mode: RS 485 and Ethernet communication.
(8) Power supply: AC (86-260V) or DC 24V.
(9) Dimensions: 96×96×136.5mm (cut size 92×92mm)
3.4. High-speed electric flow control valve
For electronic valve module, in order to meet the high-speed regulation of different sizes of flow, KaoLu has launched two series of electronic valves, one series is electric needle valve for small flow control, and the other series is electric ball valve and butterfly valve for large flow control. The biggest feature of these two series of electronic valves is that they can be electronically controlled, and have a high-speed closing time within 1s, which is a very rare fast electronic valve in Taiwan. As shown in Figure 3-5, the Electric Needle Valve FC Series combines the precision and repeatability advantages of a stepper motor with the linearity and resolution of a needle valve, resulting in less than 2% hysteresis, 2% linearity, and an adjustable flow control with 1% repeatability and 0.2% resolution is an upgraded product of the commonly used electromagnetic proportional valve. Combined with KaoLu's QKL-B3V electronic vacuum pressure controller, it can form a fast and accurate vacuum pressure closed-loop control system.
Please visit https://www.genndih.com/proportional-flow-control-valve.htm
The main technical indicators and characteristics of FC series electric needle valve are as follows:
(1) Multi-specification throttling area: from low-flow diameter 0.9mm (0~50L/min gas) to high-flow diameter 4.10mm (0 to 660 L/min gas) needle valve throttling area, It can meet different application needs.
(2) High linearity: The linearity of less than 2% simplifies the look-up table or the matching of external control hardware and software, and simplifies the relationship between command input and flow output.
(3) High repeatability: By reaching the same flow rate of 0.1% each time, the FC series electric needle valve can provide long-term stable consistency.
(4) Wide pressure range: With a vacuum of 5 or 7 bar, depending on the size of hole, the inlet environment can cover a wide pressure range. The stiffness and power of motor ensures that valve opens with the same input command, independent of pressure.
(5) Low Hysteresis: Hysteresis of less than 2% makes integration and programming simple, providing consistent flow when increasing and decreasing to the set point.
(6) High resolution: 0.2% resolution allows FC series electric needle valve to perform minimal flow adjustment according to small changes in adjustment command, providing excellent controllability.
(7) Quick response: the whole travel time is less than 1 second, which can provide timely and fast flow regulation and control.
(8) Working voltage: VDC 24V.
(9) Input signal: 4~20mA, 0~5V and 0~10V. As shown in Figure 3-6, NCBV series electric ball valve is composed of high-speed electric actuator and high-quality V-shaped ball valve, which is an upgraded product of current common used slow-speed electric ball valve. Combined with KaoLu's QKL-B3V series electronic vacuum pressure regulator, it can form a fast and accurate vacuum pressure closed-loop control system.
4. Conclusion
To sum up, through the development of a series of localized alternative products, it can basically completely replace Emerson's latest generation TESCOM ER5000 series electronic pressure controller and its back pressure valve, and low cost high performance is greatly improved. Importantly, on the basis of localized substitution, a more flexible and easy-to-use modular structure has been designed, the function expansion and technological innovation of individual modular products have been carried out, and a new type of back pressure valve and high-speed electric flow control valve have been developed. The PID controller has more powerful functions and measurement accuracy, and the whole series of localized alternative products have higher low cost high performance.
1. Emerson ER5000 series electronic pressure regulator 1.1. Structure and principle of electronic pressure regulator
Emerson's latest TESCOM ER5000 series electronic pressure regulator is a multifunctional integrated electronic pressure regulator that integrates three components: pressure sensor, PID (proportional-integral-derivative) controller and electric actuated needle valve. It is integrated with electric actuated needle valve to form a complete control mechanism. TESCOM ER5000 electronic pressure regulator and its basic structure are shown in Figure 1-1.
From Figure 1-1, we can see that function of ER5000 electronic pressure regulator is to control pressure at bottom outlet, reducing intake pressure and control it to the set pressure, so that the pressure at the bottom outlet is always consistent with the set pressure.
ER5000 electronic pressure regulator is actually an electronic pressure reducing valve, its working principle is shown in Figure 1-2.
External air source supplies pressure to ER5000, and supply pressure becomes the output pressure at outlet through opened intake valve, and this output pressure feeds back to the PID controller through the pressure sensor. If the feedback value is lower than pressure set value, the controller continues to control intake valve to open it until feedback value equals set value. When the above two values are equal, the intake valve will close, and the outlet will continue to output a constant set point pressure. If feedback value is higher than set value, the controller will actuate an exhaust valve, thereby exhausting the excess outlet pressure until feedback signal equals the set value. When the above two values are equal, the exhaust valve will close, and outlet will also continue to output a constant set point pressure.
Figure1-2 TESCOM ER500 electronic pressure regulator schematic diagram
1.2. Typical applications
ER5000 pressure controller mainly has two applied directions, one is single machine application, and the other is application work with other special valves to achieve pressure regulation and control in different ranges. (1) Single machine application: It can be seen from above structure and principle that TESCOM ER5000 electronic pressure controller is a very typical electronic pressure reducing valve. In the case of single machine use, the controller itself can reduce pressure and accurately control the gas source with pressure below 8.2bar, and even control the wide vacuum. In addition, in single machine application, it can respectively use two control modes, internal and external feedback. It shows in Figure 1-3 and Figure 1-4.
(2) Use in conjunction: An important application of ER5000 electronic pressure regulator is to use it as a pilot valve in conjunction with other regulating valves to regulate a wider pressure range. Greater pressure relief applications are shown in Figure 1-5, and are used in conjunction with a back pressure valve in Figure 1-6.
1.3. Performance indicators
Since TESCOM ER5000 series electronic pressure regulator is an integration of three parts: pressure sensor, PID controller and two-way pressure regulating valve, the technical indicators of each part represent the overall performance of the controller, and the relevant technical indicators and functions are listed as follows:
(1) Pressure control principle: double solenoid valve three-way pressure control.
(2) Medium type: clean, dry inert gas or instrument-grade air.
(3) Air intake pressure (absolute pressure): minimum (vacuum pump pressure), maximum 8.2bar (820kPa)
(4) Air outlet pressure (absolute pressure): minimum 0.07bar (7kPa), maximum 8.2bar (820kPa)
(5) Input signal: USB, RS485, 4~20mA, 1~5V or 0~10V.
(6) External sensor feedback signal: 4~20mA, 1~5V or 0~10V.
(7) Measurement accuracy of internal pressure sensor: ±0.10% (FSO), including ±0.05% (FSO) linearity and ±0.05% (FSO) hysteresis.
(8) Controller A/D conversion: 16 bits.
(9) Controller repeatability: ±0.05% (FSO).
(10) Controller resolution sensitivity: ±0.03% (FSO).
(11) Control mode: PID (combined with the special software ERTune for PID parameter debugging and optimization).
(12) Control mode: internal feedback, external feedback and double loop.
We will focus on three control modes of ER5000 electronic pressure regulator which is a technical highlight of it:
(1) Internal feedback mode: This mode only uses internal sensors. The internal feedback mode uses ER5000 internal pressure sensor to monitor absolute pressure inside the controller in range of 1~100psig/0.07~6.9bar.
(2) External feedback mode: This mode only uses external sensors. External Feedback mode utilizes a user-supplied external sensor to monitor system pressure, which is installed in pipe line and provides direct feedback to ER5000.
(3) Dual loop mode: This mode uses both internal and external sensors in a "loop-in-loop" layout. Dual loop mode executes one PID loop within another PID loop. The inner circuit uses controller's internal sensor, and the outer circuit uses external sensor.
1.4. Functions and Features
From the above introduction, the following functions and features of the ER5000 electronic pressure regulator can be summarized:
(1) The main function of ER5000 electronic pressure regulator is to control gas pressure (not flow), which can reach accurate control of pressure in sealed containers and pipelines.
(2) The overall integrated structure integrates pressure sensor, PID controller and two-way pressure regulating valve, making the overall structure small and easy to install and use in parallel with multiple units.
(3) As a typical electronic pressure regulator, it can directly reduce the air source pressure with a maximum of 8.2bar and control it accurately and constant pressure (air intake is positive pressure), and can also be used to control low pressure (wide vacuum, air intake is vacuum), and minimum pressure can reach 0.07bar (7kPa).
(4) The ER5000 electronic pressure regulator can be used as a pilot valve to drive various large-scale pressure reducing valves and back pressure valves. The outlet of controller is connected to pilot ports of other back pressure valves to realize pressure regulation and control in a larger range.
(5) The measurement accuracy of pressure sensor is ±0.1% and the 16-bit A/D conversion is a medium and high-end technical index, which can meet most applications.
(6) The digital PID control mode can reach fast speed and accurate control of pressure.
(7) Three control modes of internal feedback, external feedback and dual loop make ER5000 electronic pressure regulator have greater flexibility in use, and the best control mode can be selected according to actual use requirements.
1.5. Insufficiency of pressure controller
Although ER5000 electronic pressure regulator has many function and features mentioned above, it still has the following limitations and deficiencies in practical applications.
(1) The ER5000 electronic pressure regulator integrates three most common components in the field of vacuum pressure control; due to it is an integrated structure rather than a modular design structure. This limits application of ER5000 electronic pressure regulator. For example, ER5000 electronic pressure regulator integrates two solenoid valves, but it can only control gas pressure, but can’t control gas flow that only requires a single solenoid valve.
(2) The ER5000 electronic pressure regulator focuses more on positive pressure control, and can also work partial negative pressure control. This is mainly due to the high leak rate of valve used, so sensor (especially external sensor) and PID are not used power of control. If gas leakage rate of valve inside the controller can be reduced, the controller can completely cover the control of entire vacuum degree range, extending the current vacuum degree of 7kPa to about 1Pa.
(3) In application of driving various large-range pressure reducing valves and back pressure valves, the use of higher-priced ER5000 electronic pressure regulator as pilot valve has a very low cost performance, and electric actuated needle valve can be used.
(4) The 16-bit A/D conversion of ER5000 electronic pressure regulator is a medium and high-end technical index. If an external high-precision pressure sensor is used, a 24-bit A/D converter is required, which makes ER5000 electronic pressure regulator unable to meet some requirements in occasions that require high measurement and control accuracy.
(5) The on-site operation is very complicated. Although ER5000 electronic pressure regulator adopts PID control method, the adjustment of PID parameters requires the use of special software. The controller itself lacks PID parameter self-tuning function, and needs to be connected to a computer. (6) The ER5000 electronic pressure regulator itself lacks the display function, and it needs to connect to the computer and use the supporting software to debug and display the control process and results. (7) The overall price of ER5000 electronic pressure regulator is high, and the operation is complicated, which has higher requirements for operators. Combined with above-mentioned deficiencies of controller, this makes ER5000 electronic pressure regulator not cost-effective, and it is obviously very extravagant and wasteful to use in many occasions.
2. Localized alternative technology route
For localized replacement of Emerson's latest generation TESCOM ER5000 series electronic pressure regulator, the technical route is to first realize the measurement and control function of ER5000 electronic pressure regulator, and provide a cost-effective domestic electronic pressure regulator. Then, the module structure technology route is adopted to separate the vacuum pressure sensor, PID controller and electronic valve into their own independent modules. Each type of module is composed of a series of components with different technical indicators. Through the combination of these modules with different performance indicators, different control functions and precision requirements can be realized, and the controller functions can be expanded to meet different needs and have low cost high performance.
2.1. To reach the function of ER5000 electronic pressure regulator
(1) Localized substitute products must achieve most functions of ER5000 electronic pressure controller, that is, to realize reducing pressure and pressure control functions of ER5000 electronic pressure regulator itself.
(2) Localized substitute products, like ER5000 pressure controller, can act as a pilot valve to reduce pressure and control gas with a large range and high pressure range.
(3) Localized substitute products have the function of setting value input and display, and do not need software and connection to a computer for operation.
(4) The price of localized substitute products is low and cost-effective.
2.2. Modular structure and function expansion
(1) Modular structure is divided into three modules: sensor, PID controller and electronic valve.
(2) PID controller module is the core device of all modules which determines the measurement and control accuracy, the types of sensors and electronic valves that can be used together, the control method and control mode. PID controller module will use a 24-bit A/D converter to improve measurement and control accuracy, integrate two independent control channels. It can control 2 vacuum pressures or 1 vacuum pressure and 1 temperature at the same time. Also, it can connect a variety of vacuum pressure and temperature sensors. The combination of 2 channels can perform forward and reverse bidirectional control to meet the upstream and downstream control modes of vacuum pressure. It can have dual sensor automatic switching function to cover a wide range of measurement and control. The PID controller with program setting function can input multiple control process curves. Multiple groups of PID parameters can be input and stored, the PID parameter adjustment has self-tuning function, and the controller has a color LCD screen to display the entire process parameters and results.
3. Localized alternative products
According to above-mentioned localization alternative technical route, KaoLu has developed corresponding products, electric actuated needle valve.
3.1. Digital pressure regulator
The locally produced digital display pressure regulator includes positive pressure type and vacuum type. The pressure control principle and basic structure are the same as those of Emerson TESCOM ER5000 series electronic pressure regulator, as shown in Figure 3-1.
Please visit https://www.genndih.com/proportional-pressure-regulator.htm
The local electronic pressure regulator is also an integrated structure of three parts: a pressure sensor, a controller and a two-way pressure regulating valve. The relevant technical indicators and functions are listed as follows:
(1) Pressure control principle: double solenoid valve three-way pressure control.
(2) Medium type: clean, dry inert gas or instrument-grade air.
(3) Air intake pressure (absolute pressure): minimum (vacuum pump pressure), maximum 50bar (5MPa)
(4) Air outlet pressure (absolute pressure): minimum 0.21bar (21kPa), maximum 30bar (3M Pa)
(5) Input signal: 4~20mA, 0~5V or 0~10V.
(6) External sensor feedback signal: 4~20mA, 0~5V or 0~10V.
(7) Measurement accuracy of internal pressure sensor: ±1.0% (FSO), including ±0.5% (FSO) linearity and ±0.5% (FSO) hysteresis.
(8) Controller A/D conversion: 12 bits.
(9) Controller repeatability: ±0.5% (FSO).
(10) Controller resolution sensitivity: ±0.2% (FSO).
(11) Control method: Built-in PID automatic control, without manual intervention.
(12) Control mode: internal feedback and external feedback. It can be seen that some technical indicators of localized pressure controller have been reduced, such as 12-bit A/D conversion and ±1.0% measurement accuracy, but the use of pressure range has been expanded, also display and input functions have been added. The pressure controller can be used independently without external computer and software debugging which reduces the difficulty of operation, improves low cost high performance, and can basically meet the application in most fields.
3.2. Back pressure valve (high pressure type and vacuum type)
The locally produced new back pressure valve modules are separately divided into high pressure type and vacuum type back pressure valves. Both back pressure valves use the above digital display pressure controller as a pilot valve for control, but the new back pressure valve is not suitable for traditional back pressure valves such as Emerson TESCOM. Significant improvement has been made to the pressure valve. The traditional back pressure valve has a valve seat fixed on the valve body, and valve seat is tightly fitted with valve core to achieve sealing effect. It provides basic pressure control for most simple processes. In this design, a spring or other means provides a preset loading force that seals valve plug against valve seat. When the force of pipeline pressure acting on spool is the same as loading force, the back pressure valve works normally under preset pressure state; when pressure at the inlet end of valve increases, the force acting on spool exceeds At the preset loading force, valve core and valve seat are separated, releasing excess pressure at inlet end until preset pressure is restored. In the traditional back pressure valve structure, when instantaneous flow rate changes greatly or inlet pressure fluctuates frequently, the control pressure accuracy is low. Reasons are as follows:
(1) Since most traditional back pressure valves with a control pressure exceeding 20bar use a piston as load mechanism for spool. O-ring in piston increases friction which makes the spool act stuck.
(2) The inlet and outlet flow passages of traditional back pressure valves are mostly single passages with a fixed cross-sectional area. When flow rate at inlet of valve increases or decreases rapidly, the CV value (flow capacity) of valve does not change, it will make the inlet pressure fluctuates violently. (3) The valve core and valve seat of traditional back pressure valve, due to the need for sealing, there is stress or friction when fitting and frequent opening and closing. This will cause them to wear and consume each other, destroy the initial shape, and change CV value unpredictably. The new type of back pressure valve is a bonnet and valve body structure connected from top to bottom, as shown in Figure 3-2. A diaphragm is connected between valve cover and valve body. A pilot air hole is provided on the top of valve cover. The pilot air hole is connected to movable groove opened at the bottom of valve cover for undulating movement of the middle of diaphragm through the air source channel opened inside the valve cover, forming an up and down connection. On the side wall of valve body, there are respectively oppositely arranged medium inlet and medium outlet, medium inlet is connected with a plurality of inlet holes opened on the upper surface of valve body, and the medium outlet is connected with a plurality of outlet holes opened on the upper surface of valve body. The outstanding features of new back pressure valve are that the entire action is frictionless. Also, it does not produce pressure lag, has high inlet pressure stability and greater flow capacity.
3.3. Two-way high-precision PID controller
For PID control module, in order to meet a wide range of vacuum pressure control requirements, KaoLu has produced VPC2021 series PID controllers, which can measure, display and control vacuum, pressure and temperature. Using 24-bit data acquisition and artificial intelligence PID control technology, it can be connected to various types of vacuum, pressure and temperature sensors, and can control various types of electric needle valves, electric valves and heaters and other executive structures. It can also achieve high-precision vacuum. The fixed-point and program control of parameters such as pressure and temperature is a high-performance and cost-effective controller that replaces foreign high-end controller products.
As shown in Figure 3-3, VPC2021 series PID controller has two-way independent measurement and control function which can measure, display and control parameters on different channels at the same time. If two channels are connected to sensors of the same type but different ranges, as shown in Figure 3-4, automatic switching between two sensors can be reached according to test value, thus covering a wide range of measurement and control.
The main technical indicators of VPC2021 series dual-channel high-precision PID controller are as follows:
(1) Measurement accuracy: ±0.05%FS (24-bit A/D).
(2) Input signal: Can be connected to many vacuum pressure sensors, 32 signal input types (voltage, current, thermocouple, thermal resistance).
(3) Control output: 4 types of control output (analog signal, solid state relay, relay, SCR), which can be connected to many electric regulating valves.
(4) Control algorithm: PID control and self-tuning (20 groups of PID parameters can be stored and recalled).
(5) Control mode: fixed-point and program control, can support up to 9 control curves, each of which can be set with 24 program curves.
(6) Channel: dual channel, dual channel sensor switches automatically.
(7) Communication mode: RS 485 and Ethernet communication.
(8) Power supply: AC (86-260V) or DC 24V.
(9) Dimensions: 96×96×136.5mm (cut size 92×92mm)
3.4. High-speed electric flow control valve
For electronic valve module, in order to meet the high-speed regulation of different sizes of flow, KaoLu has launched two series of electronic valves, one series is electric needle valve for small flow control, and the other series is electric ball valve and butterfly valve for large flow control. The biggest feature of these two series of electronic valves is that they can be electronically controlled, and have a high-speed closing time within 1s, which is a very rare fast electronic valve in Taiwan. As shown in Figure 3-5, the Electric Needle Valve FC Series combines the precision and repeatability advantages of a stepper motor with the linearity and resolution of a needle valve, resulting in less than 2% hysteresis, 2% linearity, and an adjustable flow control with 1% repeatability and 0.2% resolution is an upgraded product of the commonly used electromagnetic proportional valve. Combined with KaoLu's QKL-B3V electronic vacuum pressure controller, it can form a fast and accurate vacuum pressure closed-loop control system.
Please visit https://www.genndih.com/proportional-flow-control-valve.htm
The main technical indicators and characteristics of FC series electric needle valve are as follows:
(1) Multi-specification throttling area: from low-flow diameter 0.9mm (0~50L/min gas) to high-flow diameter 4.10mm (0 to 660 L/min gas) needle valve throttling area, It can meet different application needs.
(2) High linearity: The linearity of less than 2% simplifies the look-up table or the matching of external control hardware and software, and simplifies the relationship between command input and flow output.
(3) High repeatability: By reaching the same flow rate of 0.1% each time, the FC series electric needle valve can provide long-term stable consistency.
(4) Wide pressure range: With a vacuum of 5 or 7 bar, depending on the size of hole, the inlet environment can cover a wide pressure range. The stiffness and power of motor ensures that valve opens with the same input command, independent of pressure.
(5) Low Hysteresis: Hysteresis of less than 2% makes integration and programming simple, providing consistent flow when increasing and decreasing to the set point.
(6) High resolution: 0.2% resolution allows FC series electric needle valve to perform minimal flow adjustment according to small changes in adjustment command, providing excellent controllability.
(7) Quick response: the whole travel time is less than 1 second, which can provide timely and fast flow regulation and control.
(8) Working voltage: VDC 24V.
(9) Input signal: 4~20mA, 0~5V and 0~10V. As shown in Figure 3-6, NCBV series electric ball valve is composed of high-speed electric actuator and high-quality V-shaped ball valve, which is an upgraded product of current common used slow-speed electric ball valve. Combined with KaoLu's QKL-B3V series electronic vacuum pressure regulator, it can form a fast and accurate vacuum pressure closed-loop control system.
4. Conclusion
To sum up, through the development of a series of localized alternative products, it can basically completely replace Emerson's latest generation TESCOM ER5000 series electronic pressure controller and its back pressure valve, and low cost high performance is greatly improved. Importantly, on the basis of localized substitution, a more flexible and easy-to-use modular structure has been designed, the function expansion and technological innovation of individual modular products have been carried out, and a new type of back pressure valve and high-speed electric flow control valve have been developed. The PID controller has more powerful functions and measurement accuracy, and the whole series of localized alternative products have higher low cost high performance.