FLOWX Engineer 86-21-54150349
The valve operation of both pneumatic and pneumatic actuators has its advantages and disadvantages. A valve with a pneumatic actuator can work actually at any speed without any stop for resting, while an electric actuator fails to work continuously. However, the air compressors in a pneumatic actuator is serviceable, the actuator maintenance period is very long and need little maintenance. However, the actuator maintenance period for an electric actuator is very short. Below is the detailed explanation.
The differences and the maintenance period between pneumatic and electric actuators:
Pneumatic actuators can work at any speed by controlling the air. When a set point is set, the speed can be improved, when it reaches the target set point, it will slow the speed automatically. It is more efficient and accurate; the most important part is working without any stop. The speed of electric actuators is fixed. When you set a new set point, it immediately changes to its original design speed which is very complicated and time wasting. It can only keep working in the case of not overheating. The maintenance period of the electric actuators is IEC – S4 - 25% x 15 minute x 600 start/hr.
a. The working time of the actuator is less than 25% of the time. That means if the actuator runs for 1 minute, it needs 3 minutes to cool down, then comes back to continue the operation.
b. The actuator can only operate continuously for less than 15 minutes at a time. If you force it to work over than 15 minutes with any stop, the thermal will be overload and then pop. After 45 minutes’ maintenance period, it will come back to work again.
c. for every hour, you can start and stop the electric actuator less than 600 starts. When you start the actuators, the current flow is much higher. This increased amperage becomes heat that finally burns out motor starters and windings. So it shortens the actuator maintenance period again.
The maintenance period of the actuator is various and kinds are available, for example, a 30 minute, or a 1,200 start per hour rating, but it would have extra expenses which increases the cost. These enhancements in maintenance period and frequency still need you to keep the 25% duty cycle, and then 75% is the maintenance period for the machine to cool down, otherwise the machine will break down just explained before. However, there are a few electric actuators available that can work with any rest, such as, the Jordan actuator, which can be available on valves in the ?” to 4” size range. What is more, continuous duty electro-hydraulic actuators can be useful for larger valves, but they usually need a continuous extra premium. So all in all, if you want to save money and decrease the cost, you must follow the “IEC – S4 - 25% x 15 minute x 600 start/hr”, and make sure 75% of the time is used for actuators as the maintenance period.