Yangzhou Liangye Company analyzes valve and technology automation
In order to successfully automate the process, it is important to ensure that the valve itself meets the specific requirements of the process and the media in the pipe. Usually the production process and process media can determine the type of valve, the type of spool, and the structure and materials of the trim and valve. Dust Suppression Board Roll Forming Line Dust Suppression Methods,Dust Suppression Techniques,Dust Suppression Board Roll Forming Machine,Dust Suppression Board Roll Forming Line Xinxiang Tianfeng Machinery Manufacture Co., Ltd. , https://www.frollforming.de
After the valve is selected, the next step is to consider the requirements of the automation, that is, the choice of the actuator. The actuator can be easily considered in two basic types of valve operation.
1. Rotary valve (single rotary valve)
These valves include: plug valves, ball valves, butterfly valves, and dampers or baffles. This type of valve requires an actuator with a required torque for a 90 degree rotation.
2. Multi-turn valve
These valves can be non-rotating lift stems or rotating non-lifting rods, or they require multiple turns to drive the valve to the open or closed position. Such valves include: through valves (stop valves), gate valves, knife gate valves, and the like. As an option, a linear output pneumatic or hydraulic cylinder or membrane actuator is also used to drive the valve.
There are currently four types of actuators that can use different drive energies to operate various types of valves.
Electric multi-turn actuator
Electric drive multi-turn actuators are one of the most common and reliable actuator types. Use a single-phase or three-phase motor to drive the gear or worm gear and finally drive the stem nut. The stem nut moves the stem to open or close the valve.
Multi-turn electric actuators can quickly drive large size valves. In order to protect the valve from damage, the limit switch installed at the end of the valve stroke will cut off the motor power " target=_blank> machine power, and when the safety torque is exceeded, the torque sensor will also cut off the motor power" target=_blank > Machine power, position switch is used to indicate the switch state of the valve, and the hand wheel mechanism of the clutch device can be manually operated in the event of a power failure.
The main advantage of this type of actuator is that all components are housed in a single housing that integrates all basic and advanced functions in this waterproof, dust-proof, explosion-proof enclosure. The main disadvantage is that when the power supply fails, the valve can only remain in place. Only when the backup power system is used, the valve can realize the fail-safe position (fault open or fault close)
2. Electric single-turn actuator
This type of actuator is similar to an electric multi-turn actuator. The main difference is that the final output of the actuator is a 1/4 turn 90 degree motion. The new generation of electric single-turn actuators combines the complex functions of most multi-turn actuators, such as parameter setting and diagnostics using a non-entry user-friendly operator interface.
The single-turn actuators are compact and can be mounted on small-sized valves, typically with output torques up to 800 kg. In addition, the required power supply is small and they can be fitted with batteries for fail-safe operation.
3. Fluid-driven multi-turn or linear output actuator
This type of actuator is often used to operate straight-through valves (shut-off valves) and gate valves, which use pneumatic or hydraulic operation. The structure is simple, reliable, and it is easy to implement a fail-safe mode of operation.
Typically, electric multi-turn actuators are used to drive gate and shut-off valves, and hydraulic or pneumatic actuators are only considered when there is no power.
4. Fluid-driven single-turn actuator
Pneumatic and hydraulic single-turn actuators are very versatile, they do not require a power supply and are simple in construction and reliable in performance. They are used in a wide range of fields. Usually the output ranges from a few kilograms to tens of thousands of kilometers. They use cylinders and transmissions to convert linear motion to right-angle output. Transmissions typically include: forks, rack and pinion, and levers. The rack and pinion output the same torque over the full stroke range. They are ideal for small-size valves. The forks have high efficiency. High torque output at the start of the stroke is ideal for large-diameter valves. Pneumatic actuators are typically equipped with accessories such as solenoid valves, positioners or position switches to control and monitor the valves.
This type of actuator makes it easy to implement a fail-safe mode of operation.
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