Performance Comparison of Pneumatic, Electric and Hydraulic Actuators - Shanghai Electric Ball Valve Manufacturer
Time: April 20, 2019 16:10:52 Source: Yonglong Valve Reading: zero second
Performance Comparison of Pneumatic, Electric and Hydraulic Actuators - Shanghai Electric Ball Valve Manufacturer
The first point that must be considered and clearly determined when selecting the actuator is the power source.
Power sources include pneumatic, electric and hydraulic. The electric actuator is a more general type, which is suitable for many situations. The hydraulic actuator needs the power supply provided by the hydraulic station or the special hydraulic unit of the equipment. For some remotely installed valves, there may be no power source nearby, so the process fluid must be considered as the first choice of actuator power source. The surrounding environment sets strict restrictions for the selection of actuators. For areas with high electrical hazard and high temperature environment, pneumatic actuators are the best choice.
The actuator must match the selected valve type. Most of the most commonly used pneumatic diaphragm actuators are not suitable for valves with long stroke and high thrust, while piston actuators are more suitable for such valves.
The angular travel actuator must be able to fully adapt to the necessary rotation of the valve. Different types of angular travel actuators, fork type or rack and pinion type can be selected according to the torque size and torque curve characteristics of the valve.
Performance comparison of three power source actuators:
Action speed:
Pneumatic: fast action speed, usually within 1-3 seconds.
Electric: the motor outputs torque through the gear reducer, and the action speed is relatively slow.
Hydraulic: high working pressure, very fast action speed.
Reliability:
Pneumatic: high reliability, can adapt to frequent start stop high-frequency actions, and load changes have no impact on the actuator.
Electric: frequent start and stop, motor heating, will lead to overheating protection. The increase of load transient fluctuation will cause over torque protection. Overheating or over torque protection will cause the actuator to refuse to operate.
Hydraulic: high reliability, can adapt to frequent start stop high-frequency actions, and load changes have no impact on the actuator.
No external power is required for the safety valve position
Pneumatic: safety valve position action can be realized when power source or control signal is lost, which can be fully opened, fully closed or maintained.
Electric: it can only remain in place when the power source is lost (now Shanghai Yonglong Valve Factory has an electric cut-off valve with automatic reset function in case of power failure, and the product with power failure setting open or power failure setting open).
Hydraulic: the shut-off valve can be fully closed when the power source or control signal is lost.
Adjustment control:
Pneumatic: equipped with intelligent positioner, it can realize intelligent closed-loop control with high control precision, and can set advanced diagnostic functions such as output characteristic curve, and support digital bus communication.
Electric: high control precision, advanced diagnostic functions such as output characteristic curve can be set, and digital bus communication is supported.
Hydraulics: very high control precision, smooth operation, advanced diagnostic functions such as output characteristic curve can be set, and digital bus communication is supported.
Environmental adaptability:
Pneumatic: the cylinder is the main body, so it can withstand high temperature, dust, air pollution and other adverse environmental conditions. Compressed air as power source is suitable for explosion-proof hazardous areas.
Electric: mainly motor, containing a large number of electronic components, using AC power supply as power source. It is not recommended to use in high-temperature environment and explosion-proof hazardous areas.
Hydraulic: High pressure hydraulic oil is used as the power source. It is not recommended to use in high-temperature environment and explosion-proof hazardous areas
Cost accounting:
Pneumatic: mature equipment technology, standardization, convenient installation and construction, and low project investment.
Electric: mature equipment technology, standardization, convenient installation and construction, and low project investment.
Hydraulic actuator: hydraulic actuator shall be equipped with hydraulic station and oil pipeline, which results in larger one-time investment and more installation quantities of hydraulic actuator compared with electric actuator and pneumatic actuator
Maintenance:
Pneumatic: simple structure, easy operation, low failure rate, less maintenance and long service life.
Electric: simple wiring, low failure rate and small maintenance.
Hydraulics: the system is complex, the high-pressure oil system and pipeline have oil leakage, and the maintenance is heavy.
The closing speed of the valve is critical to process operation and safety. security Shut off valve It is required to operate quickly to prevent overpressure and leakage. High speed valve operation will cause pressure fluctuation and water hammer, and damage equipment and facilities. From the perspective of ensuring the safety of the whole plant, the slight damage of the pipe support is acceptable, but any damage caused by the daily operation of the valve is unacceptable. Should be selected valve The emergency action speed of the valve can be adjusted to set the daily working speed of the valve to obtain the required control function without damage.
Spring return actuator mainly considers the reliability of fail safe function. If the valve stays in place in case of failure, the switch does not need spring load, and the double acting actuator shall be selected. One thing that cannot be ignored in transmission and control is complexity. Users must consider the technical level of local staff, dependence on equipment service engineers, maintenance costs and delay time.
Shanghai electric ball valve manufacturer's guide product: emergency shut-off valve electric shut-off valve pneumatic shut-off valve hydraulic shut-off valve gas shut-off valve Ball Valve Pneumatic ball valve electric control valve Pneumatic control valve
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