The actuator and adjustment mechanism of the pneumatic actuator are unified and the actuators are membrane type, piston type, fork type and rack and pinion type.
The actuator and adjustment mechanism of the pneumatic actuator are unified and the actuators are membrane type, piston type, fork type and rack and pinion type. The long piston stroke is suitable for applications requiring a large thrust; the diaphragm stroke is small and can only directly drive the valve stem. The fork-type pneumatic actuator has the characteristics of large torque, small space, and the torque curve is more in line with the torque curve of the valve, but it is not very beautiful; it is commonly used on high-torque valves. The rack-and-pinion pneumatic actuator has the advantages of simple structure, stable and reliable operation, safety and explosion-proof, etc. It is widely used in power plants, chemical industry, oil refining and other production processes with high safety requirements.
Working principle When the compressed air enters the pneumatic actuator from the A nozzle, the gas pushes the double piston to move linearly at both ends (cylinder end), and the rack on the piston drives the gear on the rotating shaft to rotate counterclockwise by 90 degrees, the valve is Was opened. At this time, the gas at both ends of the pneumatically actuated valve is discharged with the B nozzle. Conversely, when the compressed air enters the two ends of the pneumatic actuator from the B-guest, the gas pushes the double plug to move linearly in the middle, and the rack on the piston drives the gear on the rotating shaft to rotate clockwise by 90 degrees, and the valve is closed. At this time, the gas in the middle of the pneumatic actuator is discharged with the A nozzle. The above is the standard transmission principle. According to the user's requirements, the pneumatic actuator can be installed in the opposite principle to the standard type, that is, the timing axis is rotated clockwise to open the valve, and the counterclockwise direction is to close the valve. Single-acting (spring-return type) pneumatic actuator A nozzle is the air inlet, and B nozzle is the air outlet (B nozzle should be installed with silencer). The inlet of the A nozzle is the opening valve, and the valve is closed by the spring force when the gas is cut off.
The type and configuration of the adjustment mechanism that basically constitutes the pneumatic actuator are substantially the same, mainly due to different actuators. Therefore, when the pneumatic actuator is introduced, it is divided into two parts: the actuator and the regulating valve. The pneumatic actuator consists of two parts: the actuator and the regulating valve (adjusting mechanism). According to the size of the control signal, the corresponding thrust is generated to push the regulating valve to act. The regulating valve is the regulating part of the pneumatic actuator. Under the action of the thrust of the actuator, the regulating valve generates a certain displacement or rotation angle to directly adjust the flow of the fluid.
[1] Structure
1. The pneumatic device is mainly composed of a cylinder, a piston, a gear shaft, an end cover, a seal, a screw, etc.; the complete pneumatic device should also include an opening indication,
Internal structure travel limit, solenoid valve, positioner, pneumatic components, manual mechanism, signal feedback and other components.
2. The connection dimensions of the pneumatic device and the valve shall comply with the provisions of ISO5211 (bottom), GB/T12222 and GB/T12223.
3. Pneumatic device with manual mechanism, when the air source is interrupted, it should be able to use the manual mechanism to open and close the pneumatic ball valve. When facing the hand wheel, the hand wheel or handle should be rotated counterclockwise to open the valve, clockwise rotation The valve is closed.
4. When the end of the piston rod is internal or external, there should be a wrench opening suitable for the standard wrench.
5. The sealing ring of the piston should be easy to replace and repair.
6. Pneumatic device with buffer mechanism, the stroke length of the buffer mechanism can refer to the provisions of Table 1.
7. Pneumatic device with adjustable buffer mechanism should have a mechanism to adjust the buffering effect outside the cylinder.
8. The thread size of the inlet and outlet of the cylinder should meet the requirements of MANUR NORM (attachment standard) sypv, GB/T7306.1, GB/T7306.2 and GB/T7307.
performance
1. The rated output force or torque of the pneumatic device should meet the requirements of GB/T12222 and GB/T12223. The above is the film type actuator.
2. Under no-load conditions, the air pressure specified in Table 2 shall be input to the cylinder, and its action shall be smooth, without jamming and creeping.
3. Under the air pressure of 0.6MPa, the output torque or thrust of the pneumatic device in both directions is not less than the value indicated by the pneumatic device label, and the action should be flexible, and the permanent deformation of each part is not allowed. Other anomalies.
4. When the seal test is carried out with the maximum working pressure, the amount of air leaking from the side of each back pressure must not exceed (3+0.15D)cm3/min (standard state); leakage from the end cover and output shaft The amount of air must not exceed (3 + 0.15d) cm3 / min.
5. The strength test is carried out with a maximum working pressure of 1.5 times. After the test pressure is maintained for 3 minutes, leakage and structural deformation are not allowed in the cylinder end cover and static sealing part.
6. The number of action life times, the pneumatic device simulates the action of the pneumatic valve. In the case of maintaining the output torque or thrust capability in both directions, the number of opening and closing operations should be no less than 50,000 times (the start-close cycle is once).
7. Pneumatic device with buffer mechanism, when the piston moves to the end position of the stroke, no impact phenomenon is allowed.
Exterior
1. There shall be no scratches, cuts, blowholes, burrs, etc. on the end caps, end flanges and tanks of the casting cylinders.
2. The paint layer or chemical treatment layer on the outer surface of the pneumatic device should be smooth, smooth, uniform in color, free of oil, indentation and other mechanical damage.
Advantage
1. Accept continuous gas signal and output linear displacement (continuous electrical signal can be received after power/gas conversion device). Some can be equipped with angular arm to output angular displacement.
2. There are positive and negative functions.
3. The moving speed is large, but the speed will be slower when the load increases.
4. The output force is related to the operating pressure.
5, high reliability, but the valve can not be maintained after the gas source is interrupted (can be maintained after the retaining valve).
6. Inconvenient to achieve segmentation control and program control.
7, easy maintenance and adaptability to the environment.
8, the output power is large.
9, with an explosion-proof function.
Compact dual-piston gear, rack-and-pindle construction for precise meshing, high efficiency and constant output torque.
Aluminum cylinders, pistons and end caps are the lightest weights compared to actuators of the same size.
The cylinder is extruded aluminum alloy and hard anodized. The inner surface is hard, strong and hard. The sliding bearing made of low-friction material avoids direct contact between the metals, has low friction coefficient, flexible rotation and long service life.
Pneumatic actuators and valve mounting and connection dimensions are designed according to international standards ISO5211, DIN3337 and VDI/VDE3845 and are interchangeable with conventional pneumatic actuators.
The air supply holes conform to the NAMUR standard.
The bottom shaft mounting hole of the pneumatic actuator (according to ISO5211 standard) is double square, which is convenient for linear or 45° angle installation with square rod.
The top and top holes of the output shaft conform to the NAMUR standard.
The adjustment screws at both ends adjust the opening angle of the valve [2].
Double-acting, single-acting (spring-return) of the same specification.
The direction can be selected according to the valve needs, clockwise or counterclockwise.
Solenoid valves, positioners (opening indications), echoors, various limit switches and manual operating devices are installed according to user needs.
Disadvantages Control accuracy is low, double acting pneumatic actuator, can not return to the preset position after the gas source is cut off. Single acting pneumatic actuator that can return to the preset position by means of a spring after breaking the air supply
2 Pneumatic Actuator Classification Selection actuators are divided into three categories according to their energy forms: pneumatic, electric and hydraulic. They have their own characteristics and are suitable for different occasions. Pneumatic actuators are a category in actuators. Pneumatic actuators can also be divided into single-acting and double-acting types: the actuator's switching action is driven by the air source, called DOUBLE ACTING. SPRING RETURN (single-acting) switching action is only the air source drive when the opening action, and the spring is reset when the action is OFF.
Note: This article uses the DA/SR series pneumatic actuator as an example to illustrate the selection of the actuator. The purpose of this reference is to help the customer select the actuator correctly. The following factors must be considered before installing the pneumatic/electric actuator to the valve. * The operating torque of the valve plus the manufacturer's recommended safety factor / depending on the operating conditions. * Actuator air supply pressure or supply voltage. * Actuator type double acting or single acting (spring return) and output torque at a certain air source or output torque at rated voltage. * Steering of the actuator and failure mode (fault opening or failure closing) It is very important to select an actuator correctly. If the actuator is too large, the stem may be overstressed. Conversely, if the actuator is too small, the side cannot generate enough torque to fully operate the valve. In general, we believe that the torque required to operate the valve comes from the friction between the metal parts of the valve (such as the ball, the disc) and the seal (seat). Depending on the valve application, temperature, operating frequency, piping and differential pressure, flow medium (lubrication, drying, mud), many factors affect the operating torque. The structural principle of the ball valve is basically based on a polished core (including the channel). In the two seats (upstream and downstream), the rotation of the ball intercepts or flows through the core, and the pressure difference between the upstream and downstream forces the ball against the downstream seat (floating ball structure). The torque to operate the valve in this case is determined by the friction between the ball and the seat, the stem and the packing. As shown in Figure 1, the maximum torque occurs when a pressure differential occurs and the core rotates in the open direction.
The structural principle of the butterfly valve butterfly valve is basically based on the disc fixed to the shaft center. In the closed position, the disc is completely sealed from the valve seat. When the disc rotates (around the valve stem) and is parallel to the flow of the fluid, the valve is in the fully open position. Conversely, when the disc is perpendicular to the flow of the fluid, the valve is in the closed position. The torque of the butterfly valve is determined by the friction between the butterfly plate and the valve seat, the valve stem and the packing. At the same time, the force exerted by the pressure difference on the butterfly plate also affects the operating torque. For example, when the valve is closed, the torque is maximum, and after a slight rotation, The torque will significantly reduce the structural principle of the plug valve based on the plug sealed in the tapered plug body. There is a passage in one direction of the plug. The valve is opened and closed as the plug is screwed into the valve seat. The operating torque is generally unaffected by the pressure of the fluid but by the friction between the valve seat and the plug during opening and closing. The torque is greatest when the valve is closed. Due to the influence of pressure, the high torque is always maintained in the remaining operation.
The double-acting actuator double-acting actuator is selected as an example of a DA series pneumatic actuator. The output torque of the gear bar actuator is obtained by multiplying the piston pressure (provided by the air supply pressure) by the pitch radius (force arm), as shown in Figure 4. And the friction resistance is small and efficient. As shown in Figure 5, the output torque is linear when rotating clockwise and counterclockwise. The recommended safety factor for double acting actuators is 25-50% under normal operating conditions
The single-acting actuator single-acting actuator is selected in the SR series pneumatic actuator. In the spring-return application, the output torque is obtained in two different operating procedures. According to the stroke position, each operation produces two different Torque value. The output torque of the spring return actuator is multiplied by the force (air pressure or spring force) by the force arm. The output torque is obtained by the air pressure entering the middle cavity compression spring, which is called the "air stroke output torque". In this case, the air source pressure forces the piston to shift from 0 degrees to 90 degrees. Due to the reaction force generated by the spring compression, the torque gradually decreases from the maximum value at the starting point until the second condition: the output torque is the spring recovery when the middle chamber is out of gas. The force acting on the piston is called the "spring stroke output torque". In this case, due to the elongation of the spring, the output torque is gradually decreased from 90 degrees to 0 degrees. As described above, the single-acting actuator is based on two Under the condition of generating a balance torque based on the design. As shown in Figure 11. In each case, by changing the relationship between the number of springs on each side and the pressure of the source (eg 2 springs per side and 5.5 bar gas source or vice versa), it is possible to obtain unbalanced torque. Two conditions are available in spring-return applications. : Loss of gas or gas loss. The recommended safety factor for spring return actuators is 25-50% under normal operating conditions.
Example of selection of spring return actuators (see also technical data sheet):
Spring off (gas loss)
*The torque of the ball valve = 80NM
*Safety factor (25%) = 80NM + 25% = 100NM
*Air source pressure = 0.6MPa
The selected SY-SR actuator is SR125-05 because the following values ​​can be generated:
*Spring stroke 0o=119.2NM
*Spring stroke 90o=216.2NM
* Air stroke 0o = 228.7NM
* Air stroke 90o = 118.8NM
4Product IntroductionEdit DR/SC New Rack and Pinion
R/SC's new rack-and-pinion pneumatic actuators are beautiful, compact and modern in shape; they use practical new materials and new processes to make the quality and performance of the products more reliable; multi-special selection is more economical; the products are fully in line with the latest international Standard technical specifications. 1 rig and pinion double piston symmetrical structure design, fast and stable action, high precision, large output power, can be rotated in the opposite direction by simply changing the piston assembly position.
2 extruded high-quality aluminum alloy cylinders, hard anodized by precision machined inner and outer surfaces (anodized Teflon coating under special circumstances), longer service life and low friction coefficient.
The DR/SC new rack-and-pinion pneumatic actuator 3 is an all-in-one design. All double-acting and single-acting actuator models have the same cylinder and end caps. It is easy to change the way of action by adding springs or removing springs. .
4 Combined pre-loaded safety spring set, which can easily and safely install or increase the number of springs in the assembly process or in the field of use.
5 External side two separate adjustment screws for the actuators already installed on the valve are more precise and convenient, adjust the valve opening and valve closing position, if you need full stroke adjustment, then configure the longer adjustment screw at the two end covers.
6 multi-function position indicator, on-site visual indication, in line with VID/VIE3845, NAMUR standard slot, can install and output all accessories, such as limit switch box, electric positioner, position sensor (Pegaft, Turck).
The 7 air source interface complies with the NRMAR standard and can be directly installed with NUMAR standard solenoid valves.
The composite bush and the piston guide ring on the back of the rack and the bearings of the output shaft prevent the metal from rubbing against the metal and increase the lubrication to make it low friction and long life.
9 All fasteners are made of stainless steel "target=_blank> stainless steel material for long-term corrosion resistance.
The 10 connection parts comply with the new international standard specification ISO5211, and DIN3337 (F03-F25) makes the production and installation interchangeable and versatile.
GT series valve pneumatic device
The GT series valve pneumatic device is a newly developed partial rotary pneumatic actuator with an output shaft rotation angle of 90°. It can be combined with ball valves, butterfly valves and other valves into pneumatic valves, as well as other mechanical devices that require 90° rotary motion. The product can be used to control the two positions of the opening and closing and the different requirements of the continuous motion control (automatic adjustment control) by using accessories such as solenoid valves. Users can choose according to actual needs.
The same specifications are double-acting, single-acting (spring reset).
The standard rotary axis angle can be adjusted from -5 to 5 °C.
All sliding parts are made of plastic bearing bushings, guided to maintain minimum friction and effectively resist wear.
The surface of the casing is anodized and plated for corrosion protection; the rotating shaft is plated with hard nickel-phosphorus alloy; the screw and nut are stainless steel "target=_blank> stainless steel.
Single-acting springs are pre-assembled in the spring seat for easy assembly or addition of springs.
Connection and installation interface standardization module design, easy to install ball valve, butterfly valve, signal box and control accessories.
The rotation direction can be selected to rotate clockwise or counterclockwise; the adjustment screws at both ends can be adjusted to be smaller than the calibration angle.
Special corrosion environment can be stainless steel " target=_blank> stainless steel casing PSS new pneumatic actuator
Pneumatic Italian OMAL pneumatic actuators are distinguished from other actuators by their unique structural features. Their unique fork mechanism, combined with its patented technology, makes its pneumatic actuators far superior to other competitors.
OMAL pneumatic actuators are small in size, light in weight, large in torque and long in life. The pneumatic actuator adopts the "single cylinder double piston-pull type variable torque" transmission structure, and the low friction, long life multi-point guided patent sealing technology, and uses PTFE-carbon graphite as the standard piston sealing material to make its output torque. Meet the torque change requirements of the gate switch. In addition, the "Scotch-joke" high-torque structure of the OMAL pneumatic actuator is designed for the maximum torque required for the starting or closing point of the valve. The structure is novel and flexible, and the linear motion of the actuator piston is converted into the output shaft. The rotary motion produces a 50% greater starting torque than a conventional rack and pinion pneumatic actuator.
Fork type
OMAL is the first manufacturer of fork-type pneumatic actuators in Europe. Its small size, high torque and long life, torque from 8NM to 8000NM, suitable for all industries, fork actuators. The original fork design produces a stronger starting torque and closes the torque, which better meets the butterfly valve control requirements. Multi-point guide seal (patented technology) PTFE + carbon graphite piston seal meets the requirements of harsh environments; multi-point guide sealing technology enables life of more than 1.5 million times
1. Low friction PTFE graphite piston seal
2.For-Life multi-point steering drive
3. Fork type large torque structure
4. Less air consumption
5. Smaller volume
6. Lighter quality
7. Long life (cycle) – less wear and tear
8. Faster action
AT pneumatic execution structure
The AT pneumatic actuator is divided into two types: positive action and reverse action. The so-called positive action is that the signal pressure is increased and the push rod is downward; the reaction form is that the signal pressure is increased and the push rod is upward. The output displacement of this actuator is proportional to the input air pressure signal. The larger the signal pressure, the larger the displacement of the push rod. When the pressure is balanced with the reaction force of the spring, the push rod is stabilized at a certain position, and the AT pneumatic actuator has two kinds of angular stroke pneumatic actuators and straight stroke pneumatic actuators. With the continuous development of intelligent pneumatic actuators, intelligent valve positioners have become an indispensable accessory product. The intelligent valve positioner contains a highly integrated microcontroller, which uses the principle of electric balance (digital balance) instead of the traditional force balance principle, and converts the electronic control command into a pneumatic positioning increment to realize the valve position control; using digital opening and stopping The off signal drives the action of the pneumatic actuator; the valve position feedback signal directly passes the high-precision position sensor to realize the electric/gas conversion function. The intelligent valve positioner has the characteristics of improving output force and movement speed, adjusting precision, overcoming the friction of the valve stem, and achieving correct positioning. It is precisely because of the continuous intelligence of these accessory products that the pneumatic actuators are more intelligent.
Because the actuator of the pneumatic actuator has the advantages of simple structure, large output thrust, stable and reliable action, safety and explosion-proof, it is widely used in the production process with high safety requirements such as chemical industry and oil refining.
installation
1. The pneumatic actuator can be directly connected to the valve, or it can be installed and connected through the bracket and the joint. The coupling fasteners must not be loose.
2. Ensure the coaxiality of the output shaft of the actuator and the valve stem installation, and the rotation is flexible, without creeping phenomenon.
3. The connecting pipes, joints, accessories, etc. should be clean.
4. The exhaust port of the solenoid valve is always down. When it is up or horizontal, the elbow should be connected so that the exhaust port is down.
5. Before the commissioning, it should be confirmed that the air duct is unobstructed, and the air pressure, voltage and signal meet the requirements.
6. The compressed air should be filtered, dried, and dehumidified below -15 °C.
7. The solenoid valve should be opened to the automatic position during commissioning.
8. When pneumatically operated, the manual device should be disconnected, and the pneumatic device should be disconnected during manual operation.
9. Various accessories installed on the actuator should be debugged according to the instruction manual.
10. Check once a month under normal working conditions and overhaul once a year.
5 after sales service
1. Service tenet: fast, decisive, accurate, thoughtful and thorough.
2, service objectives: service quality to win customer satisfaction.
3. Service efficiency: If the equipment fails during the warranty period or outside the warranty period, if the supplier needs to solve the problem on-site after receiving the notice, send a professional technical service personnel to arrive at the scene within 24 hours (the 48-hour journey is far away) To) and do the problem does not solve the service personnel do not evacuate.
4. Service principle: The warranty period of the product is 12 months. During the warranty period, the supplier will repair and replace the parts damaged by quality for free. [1]6Compared with electric actuators In terms of technical performance, the advantages of pneumatic actuators mainly include the following four aspects:
(1) The load is large and can be adapted to high torque output applications.
(2) Quick action and quick response.
(3) The working environment has good adaptability, especially in the harsh working environment such as flammable, explosive, dusty, strong magnetic, radiation and vibration, which is superior to hydraulic, electronic and electrical control.
(4) The motor is easily damaged when the stroke is blocked or the valve stem is stuck.
The advantages of electric actuators include:
(1) Compact structure and small size. Compared to pneumatic actuators, electric actuators are relatively simple in construction. A basic electronic system consists of actuators, three-position DPDT switches, fuses and some wires for easy assembly.
(2) The drive source of the electric actuator is very flexible. Generally, the vehicle power supply can meet the needs, and the pneumatic actuator requires a gas source and a compression drive device.
(3) The electric actuator has no danger of “leakage†and has high reliability, and the compressibility of the air makes the stability of the pneumatic actuator slightly poor.
(4) There is no need to install and maintain various pneumatic lines.
(5) The load can be maintained without power, and the pneumatic actuator requires constant pressure supply.
(6) The electric actuator is quieter because no additional pressure devices are required. Usually, if the pneumatic actuator is under heavy load, a silencer is added.
(7) In a pneumatic device, it is usually necessary to convert an electrical signal into a gas signal, and then convert it into an electrical signal, and the transmission speed is slow, and it is not suitable for a complicated circuit with too many component stages.
(8) Electric actuators are superior in control accuracy.
In fact, pneumatic and electric systems are not mutually exclusive. Pneumatic actuators can be easily realized in a fast linear cycle. The structure is simple and easy to maintain. It can also be used in a variety of harsh working environments, such as explosion-proof requirements, dusty or wet conditions. However, an electric drive with a servo motor has an advantage in the case where the force is rapidly increased and precise positioning is required. For applications requiring precise, synchronized operation, adjustable and specified positioning programming, electric drives are the best choice. The electric drive system consisting of servo or stepper motors with closed-loop positioning controllers can complement the shortcomings of pneumatic systems. Where.
In modern control, various systems are more and more complex and more and more sophisticated. It is not a kind of drive control technology that can satisfy various control functions of the system. Electric actuators are mainly used in applications requiring precise control. The requirements for flexibility in automation equipment are constantly increasing. The same equipment is often required to adapt to the processing needs of different sizes of workpieces. The actuator needs to be controlled by multiple points, and the actuator must be Accurate control or simultaneous tracking of operating speed and torque is not possible with conventional pneumatic control, which is easily achieved with electric actuators. It can be seen that the pneumatic actuator is more suitable for simple motion control, while the electric actuator is mostly used for precision motion control. http://news.chinawj.com.cn Edit: (Hardware Business Network Information Center) http:// News.chinawj.com.cn
The actuator and adjustment mechanism of the pneumatic actuator are unified and the actuators are membrane type, piston type, fork type and rack and pinion type. The long piston stroke is suitable for applications requiring a large thrust; the diaphragm stroke is small and can only directly drive the valve stem. The fork-type pneumatic actuator has the characteristics of large torque, small space, and the torque curve is more in line with the torque curve of the valve, but it is not very beautiful; it is commonly used on high-torque valves. The rack-and-pinion pneumatic actuator has the advantages of simple structure, stable and reliable operation, safety and explosion-proof, etc. It is widely used in power plants, chemical industry, oil refining and other production processes with high safety requirements.
Working principle When the compressed air enters the pneumatic actuator from the A nozzle, the gas pushes the double piston to move linearly at both ends (cylinder end), and the rack on the piston drives the gear on the rotating shaft to rotate counterclockwise by 90 degrees, the valve is Was opened. At this time, the gas at both ends of the pneumatically actuated valve is discharged with the B nozzle. Conversely, when the compressed air enters the two ends of the pneumatic actuator from the B-guest, the gas pushes the double plug to move linearly in the middle, and the rack on the piston drives the gear on the rotating shaft to rotate clockwise by 90 degrees, and the valve is closed. At this time, the gas in the middle of the pneumatic actuator is discharged with the A nozzle. The above is the standard transmission principle. According to the user's requirements, the pneumatic actuator can be installed in the opposite principle to the standard type, that is, the timing axis is rotated clockwise to open the valve, and the counterclockwise direction is to close the valve. Single-acting (spring-return type) pneumatic actuator A nozzle is the air inlet, and B nozzle is the air outlet (B nozzle should be installed with silencer). The inlet of the A nozzle is the opening valve, and the valve is closed by the spring force when the gas is cut off.
The type and configuration of the adjustment mechanism that basically constitutes the pneumatic actuator are substantially the same, mainly due to different actuators. Therefore, when the pneumatic actuator is introduced, it is divided into two parts: the actuator and the regulating valve. The pneumatic actuator consists of two parts: the actuator and the regulating valve (adjusting mechanism). According to the size of the control signal, the corresponding thrust is generated to push the regulating valve to act. The regulating valve is the regulating part of the pneumatic actuator. Under the action of the thrust of the actuator, the regulating valve generates a certain displacement or rotation angle to directly adjust the flow of the fluid.
[1] Structure
1. The pneumatic device is mainly composed of a cylinder, a piston, a gear shaft, an end cover, a seal, a screw, etc.; the complete pneumatic device should also include an opening indication,
Internal structure travel limit, solenoid valve, positioner, pneumatic components, manual mechanism, signal feedback and other components.
2. The connection dimensions of the pneumatic device and the valve shall comply with the provisions of ISO5211 (bottom), GB/T12222 and GB/T12223.
3. Pneumatic device with manual mechanism, when the air source is interrupted, it should be able to use the manual mechanism to open and close the pneumatic ball valve. When facing the hand wheel, the hand wheel or handle should be rotated counterclockwise to open the valve, clockwise rotation The valve is closed.
4. When the end of the piston rod is internal or external, there should be a wrench opening suitable for the standard wrench.
5. The sealing ring of the piston should be easy to replace and repair.
6. Pneumatic device with buffer mechanism, the stroke length of the buffer mechanism can refer to the provisions of Table 1.
7. Pneumatic device with adjustable buffer mechanism should have a mechanism to adjust the buffering effect outside the cylinder.
8. The thread size of the inlet and outlet of the cylinder should meet the requirements of MANUR NORM (attachment standard) sypv, GB/T7306.1, GB/T7306.2 and GB/T7307.
performance
1. The rated output force or torque of the pneumatic device should meet the requirements of GB/T12222 and GB/T12223. The above is the film type actuator.
2. Under no-load conditions, the air pressure specified in Table 2 shall be input to the cylinder, and its action shall be smooth, without jamming and creeping.
3. Under the air pressure of 0.6MPa, the output torque or thrust of the pneumatic device in both directions is not less than the value indicated by the pneumatic device label, and the action should be flexible, and the permanent deformation of each part is not allowed. Other anomalies.
4. When the seal test is carried out with the maximum working pressure, the amount of air leaking from the side of each back pressure must not exceed (3+0.15D)cm3/min (standard state); leakage from the end cover and output shaft The amount of air must not exceed (3 + 0.15d) cm3 / min.
5. The strength test is carried out with a maximum working pressure of 1.5 times. After the test pressure is maintained for 3 minutes, leakage and structural deformation are not allowed in the cylinder end cover and static sealing part.
6. The number of action life times, the pneumatic device simulates the action of the pneumatic valve. In the case of maintaining the output torque or thrust capability in both directions, the number of opening and closing operations should be no less than 50,000 times (the start-close cycle is once).
7. Pneumatic device with buffer mechanism, when the piston moves to the end position of the stroke, no impact phenomenon is allowed.
Exterior
1. There shall be no scratches, cuts, blowholes, burrs, etc. on the end caps, end flanges and tanks of the casting cylinders.
2. The paint layer or chemical treatment layer on the outer surface of the pneumatic device should be smooth, smooth, uniform in color, free of oil, indentation and other mechanical damage.
Advantage
1. Accept continuous gas signal and output linear displacement (continuous electrical signal can be received after power/gas conversion device). Some can be equipped with angular arm to output angular displacement.
2. There are positive and negative functions.
3. The moving speed is large, but the speed will be slower when the load increases.
4. The output force is related to the operating pressure.
5, high reliability, but the valve can not be maintained after the gas source is interrupted (can be maintained after the retaining valve).
6. Inconvenient to achieve segmentation control and program control.
7, easy maintenance and adaptability to the environment.
8, the output power is large.
9, with an explosion-proof function.
Compact dual-piston gear, rack-and-pindle construction for precise meshing, high efficiency and constant output torque.
Aluminum cylinders, pistons and end caps are the lightest weights compared to actuators of the same size.
The cylinder is extruded aluminum alloy and hard anodized. The inner surface is hard, strong and hard. The sliding bearing made of low-friction material avoids direct contact between the metals, has low friction coefficient, flexible rotation and long service life.
Pneumatic actuators and valve mounting and connection dimensions are designed according to international standards ISO5211, DIN3337 and VDI/VDE3845 and are interchangeable with conventional pneumatic actuators.
The air supply holes conform to the NAMUR standard.
The bottom shaft mounting hole of the pneumatic actuator (according to ISO5211 standard) is double square, which is convenient for linear or 45° angle installation with square rod.
The top and top holes of the output shaft conform to the NAMUR standard.
The adjustment screws at both ends adjust the opening angle of the valve [2].
Double-acting, single-acting (spring-return) of the same specification.
The direction can be selected according to the valve needs, clockwise or counterclockwise.
Solenoid valves, positioners (opening indications), echoors, various limit switches and manual operating devices are installed according to user needs.
Disadvantages Control accuracy is low, double acting pneumatic actuator, can not return to the preset position after the gas source is cut off. Single acting pneumatic actuator that can return to the preset position by means of a spring after breaking the air supply
2 Pneumatic Actuator Classification Selection actuators are divided into three categories according to their energy forms: pneumatic, electric and hydraulic. They have their own characteristics and are suitable for different occasions. Pneumatic actuators are a category in actuators. Pneumatic actuators can also be divided into single-acting and double-acting types: the actuator's switching action is driven by the air source, called DOUBLE ACTING. SPRING RETURN (single-acting) switching action is only the air source drive when the opening action, and the spring is reset when the action is OFF.
Note: This article uses the DA/SR series pneumatic actuator as an example to illustrate the selection of the actuator. The purpose of this reference is to help the customer select the actuator correctly. The following factors must be considered before installing the pneumatic/electric actuator to the valve. * The operating torque of the valve plus the manufacturer's recommended safety factor / depending on the operating conditions. * Actuator air supply pressure or supply voltage. * Actuator type double acting or single acting (spring return) and output torque at a certain air source or output torque at rated voltage. * Steering of the actuator and failure mode (fault opening or failure closing) It is very important to select an actuator correctly. If the actuator is too large, the stem may be overstressed. Conversely, if the actuator is too small, the side cannot generate enough torque to fully operate the valve. In general, we believe that the torque required to operate the valve comes from the friction between the metal parts of the valve (such as the ball, the disc) and the seal (seat). Depending on the valve application, temperature, operating frequency, piping and differential pressure, flow medium (lubrication, drying, mud), many factors affect the operating torque. The structural principle of the ball valve is basically based on a polished core (including the channel). In the two seats (upstream and downstream), the rotation of the ball intercepts or flows through the core, and the pressure difference between the upstream and downstream forces the ball against the downstream seat (floating ball structure). The torque to operate the valve in this case is determined by the friction between the ball and the seat, the stem and the packing. As shown in Figure 1, the maximum torque occurs when a pressure differential occurs and the core rotates in the open direction.
The structural principle of the butterfly valve butterfly valve is basically based on the disc fixed to the shaft center. In the closed position, the disc is completely sealed from the valve seat. When the disc rotates (around the valve stem) and is parallel to the flow of the fluid, the valve is in the fully open position. Conversely, when the disc is perpendicular to the flow of the fluid, the valve is in the closed position. The torque of the butterfly valve is determined by the friction between the butterfly plate and the valve seat, the valve stem and the packing. At the same time, the force exerted by the pressure difference on the butterfly plate also affects the operating torque. For example, when the valve is closed, the torque is maximum, and after a slight rotation, The torque will significantly reduce the structural principle of the plug valve based on the plug sealed in the tapered plug body. There is a passage in one direction of the plug. The valve is opened and closed as the plug is screwed into the valve seat. The operating torque is generally unaffected by the pressure of the fluid but by the friction between the valve seat and the plug during opening and closing. The torque is greatest when the valve is closed. Due to the influence of pressure, the high torque is always maintained in the remaining operation.
The double-acting actuator double-acting actuator is selected as an example of a DA series pneumatic actuator. The output torque of the gear bar actuator is obtained by multiplying the piston pressure (provided by the air supply pressure) by the pitch radius (force arm), as shown in Figure 4. And the friction resistance is small and efficient. As shown in Figure 5, the output torque is linear when rotating clockwise and counterclockwise. The recommended safety factor for double acting actuators is 25-50% under normal operating conditions
The single-acting actuator single-acting actuator is selected in the SR series pneumatic actuator. In the spring-return application, the output torque is obtained in two different operating procedures. According to the stroke position, each operation produces two different Torque value. The output torque of the spring return actuator is multiplied by the force (air pressure or spring force) by the force arm. The output torque is obtained by the air pressure entering the middle cavity compression spring, which is called the "air stroke output torque". In this case, the air source pressure forces the piston to shift from 0 degrees to 90 degrees. Due to the reaction force generated by the spring compression, the torque gradually decreases from the maximum value at the starting point until the second condition: the output torque is the spring recovery when the middle chamber is out of gas. The force acting on the piston is called the "spring stroke output torque". In this case, due to the elongation of the spring, the output torque is gradually decreased from 90 degrees to 0 degrees. As described above, the single-acting actuator is based on two Under the condition of generating a balance torque based on the design. As shown in Figure 11. In each case, by changing the relationship between the number of springs on each side and the pressure of the source (eg 2 springs per side and 5.5 bar gas source or vice versa), it is possible to obtain unbalanced torque. Two conditions are available in spring-return applications. : Loss of gas or gas loss. The recommended safety factor for spring return actuators is 25-50% under normal operating conditions.
Example of selection of spring return actuators (see also technical data sheet):
Spring off (gas loss)
*The torque of the ball valve = 80NM
*Safety factor (25%) = 80NM + 25% = 100NM
*Air source pressure = 0.6MPa
The selected SY-SR actuator is SR125-05 because the following values ​​can be generated:
*Spring stroke 0o=119.2NM
*Spring stroke 90o=216.2NM
* Air stroke 0o = 228.7NM
* Air stroke 90o = 118.8NM
4Product IntroductionEdit DR/SC New Rack and Pinion
R/SC's new rack-and-pinion pneumatic actuators are beautiful, compact and modern in shape; they use practical new materials and new processes to make the quality and performance of the products more reliable; multi-special selection is more economical; the products are fully in line with the latest international Standard technical specifications. 1 rig and pinion double piston symmetrical structure design, fast and stable action, high precision, large output power, can be rotated in the opposite direction by simply changing the piston assembly position.
2 extruded high-quality aluminum alloy cylinders, hard anodized by precision machined inner and outer surfaces (anodized Teflon coating under special circumstances), longer service life and low friction coefficient.
The DR/SC new rack-and-pinion pneumatic actuator 3 is an all-in-one design. All double-acting and single-acting actuator models have the same cylinder and end caps. It is easy to change the way of action by adding springs or removing springs. .
4 Combined pre-loaded safety spring set, which can easily and safely install or increase the number of springs in the assembly process or in the field of use.
5 External side two separate adjustment screws for the actuators already installed on the valve are more precise and convenient, adjust the valve opening and valve closing position, if you need full stroke adjustment, then configure the longer adjustment screw at the two end covers.
6 multi-function position indicator, on-site visual indication, in line with VID/VIE3845, NAMUR standard slot, can install and output all accessories, such as limit switch box, electric positioner, position sensor (Pegaft, Turck).
The 7 air source interface complies with the NRMAR standard and can be directly installed with NUMAR standard solenoid valves.
The composite bush and the piston guide ring on the back of the rack and the bearings of the output shaft prevent the metal from rubbing against the metal and increase the lubrication to make it low friction and long life.
9 All fasteners are made of stainless steel "target=_blank> stainless steel material for long-term corrosion resistance.
The 10 connection parts comply with the new international standard specification ISO5211, and DIN3337 (F03-F25) makes the production and installation interchangeable and versatile.
GT series valve pneumatic device
The GT series valve pneumatic device is a newly developed partial rotary pneumatic actuator with an output shaft rotation angle of 90°. It can be combined with ball valves, butterfly valves and other valves into pneumatic valves, as well as other mechanical devices that require 90° rotary motion. The product can be used to control the two positions of the opening and closing and the different requirements of the continuous motion control (automatic adjustment control) by using accessories such as solenoid valves. Users can choose according to actual needs.
The same specifications are double-acting, single-acting (spring reset).
The standard rotary axis angle can be adjusted from -5 to 5 °C.
All sliding parts are made of plastic bearing bushings, guided to maintain minimum friction and effectively resist wear.
The surface of the casing is anodized and plated for corrosion protection; the rotating shaft is plated with hard nickel-phosphorus alloy; the screw and nut are stainless steel "target=_blank> stainless steel.
Single-acting springs are pre-assembled in the spring seat for easy assembly or addition of springs.
Connection and installation interface standardization module design, easy to install ball valve, butterfly valve, signal box and control accessories.
The rotation direction can be selected to rotate clockwise or counterclockwise; the adjustment screws at both ends can be adjusted to be smaller than the calibration angle.
Special corrosion environment can be stainless steel " target=_blank> stainless steel casing PSS new pneumatic actuator
Pneumatic Italian OMAL pneumatic actuators are distinguished from other actuators by their unique structural features. Their unique fork mechanism, combined with its patented technology, makes its pneumatic actuators far superior to other competitors.
OMAL pneumatic actuators are small in size, light in weight, large in torque and long in life. The pneumatic actuator adopts the "single cylinder double piston-pull type variable torque" transmission structure, and the low friction, long life multi-point guided patent sealing technology, and uses PTFE-carbon graphite as the standard piston sealing material to make its output torque. Meet the torque change requirements of the gate switch. In addition, the "Scotch-joke" high-torque structure of the OMAL pneumatic actuator is designed for the maximum torque required for the starting or closing point of the valve. The structure is novel and flexible, and the linear motion of the actuator piston is converted into the output shaft. The rotary motion produces a 50% greater starting torque than a conventional rack and pinion pneumatic actuator.
Fork type
OMAL is the first manufacturer of fork-type pneumatic actuators in Europe. Its small size, high torque and long life, torque from 8NM to 8000NM, suitable for all industries, fork actuators. The original fork design produces a stronger starting torque and closes the torque, which better meets the butterfly valve control requirements. Multi-point guide seal (patented technology) PTFE + carbon graphite piston seal meets the requirements of harsh environments; multi-point guide sealing technology enables life of more than 1.5 million times
1. Low friction PTFE graphite piston seal
2.For-Life multi-point steering drive
3. Fork type large torque structure
4. Less air consumption
5. Smaller volume
6. Lighter quality
7. Long life (cycle) – less wear and tear
8. Faster action
AT pneumatic execution structure
The AT pneumatic actuator is divided into two types: positive action and reverse action. The so-called positive action is that the signal pressure is increased and the push rod is downward; the reaction form is that the signal pressure is increased and the push rod is upward. The output displacement of this actuator is proportional to the input air pressure signal. The larger the signal pressure, the larger the displacement of the push rod. When the pressure is balanced with the reaction force of the spring, the push rod is stabilized at a certain position, and the AT pneumatic actuator has two kinds of angular stroke pneumatic actuators and straight stroke pneumatic actuators. With the continuous development of intelligent pneumatic actuators, intelligent valve positioners have become an indispensable accessory product. The intelligent valve positioner contains a highly integrated microcontroller, which uses the principle of electric balance (digital balance) instead of the traditional force balance principle, and converts the electronic control command into a pneumatic positioning increment to realize the valve position control; using digital opening and stopping The off signal drives the action of the pneumatic actuator; the valve position feedback signal directly passes the high-precision position sensor to realize the electric/gas conversion function. The intelligent valve positioner has the characteristics of improving output force and movement speed, adjusting precision, overcoming the friction of the valve stem, and achieving correct positioning. It is precisely because of the continuous intelligence of these accessory products that the pneumatic actuators are more intelligent.
Because the actuator of the pneumatic actuator has the advantages of simple structure, large output thrust, stable and reliable action, safety and explosion-proof, it is widely used in the production process with high safety requirements such as chemical industry and oil refining.
installation
1. The pneumatic actuator can be directly connected to the valve, or it can be installed and connected through the bracket and the joint. The coupling fasteners must not be loose.
2. Ensure the coaxiality of the output shaft of the actuator and the valve stem installation, and the rotation is flexible, without creeping phenomenon.
3. The connecting pipes, joints, accessories, etc. should be clean.
4. The exhaust port of the solenoid valve is always down. When it is up or horizontal, the elbow should be connected so that the exhaust port is down.
5. Before the commissioning, it should be confirmed that the air duct is unobstructed, and the air pressure, voltage and signal meet the requirements.
6. The compressed air should be filtered, dried, and dehumidified below -15 °C.
7. The solenoid valve should be opened to the automatic position during commissioning.
8. When pneumatically operated, the manual device should be disconnected, and the pneumatic device should be disconnected during manual operation.
9. Various accessories installed on the actuator should be debugged according to the instruction manual.
10. Check once a month under normal working conditions and overhaul once a year.
5 after sales service
1. Service tenet: fast, decisive, accurate, thoughtful and thorough.
2, service objectives: service quality to win customer satisfaction.
3. Service efficiency: If the equipment fails during the warranty period or outside the warranty period, if the supplier needs to solve the problem on-site after receiving the notice, send a professional technical service personnel to arrive at the scene within 24 hours (the 48-hour journey is far away) To) and do the problem does not solve the service personnel do not evacuate.
4. Service principle: The warranty period of the product is 12 months. During the warranty period, the supplier will repair and replace the parts damaged by quality for free. [1]6Compared with electric actuators In terms of technical performance, the advantages of pneumatic actuators mainly include the following four aspects:
(1) The load is large and can be adapted to high torque output applications.
(2) Quick action and quick response.
(3) The working environment has good adaptability, especially in the harsh working environment such as flammable, explosive, dusty, strong magnetic, radiation and vibration, which is superior to hydraulic, electronic and electrical control.
(4) The motor is easily damaged when the stroke is blocked or the valve stem is stuck.
The advantages of electric actuators include:
(1) Compact structure and small size. Compared to pneumatic actuators, electric actuators are relatively simple in construction. A basic electronic system consists of actuators, three-position DPDT switches, fuses and some wires for easy assembly.
(2) The drive source of the electric actuator is very flexible. Generally, the vehicle power supply can meet the needs, and the pneumatic actuator requires a gas source and a compression drive device.
(3) The electric actuator has no danger of “leakage†and has high reliability, and the compressibility of the air makes the stability of the pneumatic actuator slightly poor.
(4) There is no need to install and maintain various pneumatic lines.
(5) The load can be maintained without power, and the pneumatic actuator requires constant pressure supply.
(6) The electric actuator is quieter because no additional pressure devices are required. Usually, if the pneumatic actuator is under heavy load, a silencer is added.
(7) In a pneumatic device, it is usually necessary to convert an electrical signal into a gas signal, and then convert it into an electrical signal, and the transmission speed is slow, and it is not suitable for a complicated circuit with too many component stages.
(8) Electric actuators are superior in control accuracy.
In fact, pneumatic and electric systems are not mutually exclusive. Pneumatic actuators can be easily realized in a fast linear cycle. The structure is simple and easy to maintain. It can also be used in a variety of harsh working environments, such as explosion-proof requirements, dusty or wet conditions. However, an electric drive with a servo motor has an advantage in the case where the force is rapidly increased and precise positioning is required. For applications requiring precise, synchronized operation, adjustable and specified positioning programming, electric drives are the best choice. The electric drive system consisting of servo or stepper motors with closed-loop positioning controllers can complement the shortcomings of pneumatic systems. Where.
In modern control, various systems are more and more complex and more and more sophisticated. It is not a kind of drive control technology that can satisfy various control functions of the system. Electric actuators are mainly used in applications requiring precise control. The requirements for flexibility in automation equipment are constantly increasing. The same equipment is often required to adapt to the processing needs of different sizes of workpieces. The actuator needs to be controlled by multiple points, and the actuator must be Accurate control or simultaneous tracking of operating speed and torque is not possible with conventional pneumatic control, which is easily achieved with electric actuators. It can be seen that the pneumatic actuator is more suitable for simple motion control, while the electric actuator is mostly used for precision motion control. http://news.chinawj.com.cn Edit: (Hardware Business Network Information Center) http:// News.chinawj.com.cn
China Electric Water Heater, WATER HEATER ,Big Power Gas Water Heater Supplier
Electric Water Heater ,Water Heater,Big Power Gas Water Heater,Gas Water Heater
China Electric Water Heater,Water Heater supplier & manufacturer, offer low price, high quality Big Power Gas Water Heater,Gas Water Heater, etc.
This is belong to Flue Type Gas Water Heater,20min auto-flameout timer,it is very fast and safe device .it had 6L-12L can be choose ,very easliy to handle it
Low Water Pressure Starting can be .we will support best quality for our cusotmers for win win business for future for us .
WATER HEATER
Electric Water Heater,Water Heater,Big Power Gas Water Heater,Gas Water Heater
GUANGZHOU AIJINGSI TRADING LIMITED , https://www.aichugashob.com