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1. Drive Energy The most common drive energy source is the power supply or fluid source. If the power source is selected as the drive energy source , a three-phase power supply is generally used for large-size valves, and a single-phase power supply is available for small-size valves. General electric actuators can have a variety of power supply types to choose from. DC power may also be available in some cases. This can be achieved by installing a battery for fail-safe power operation.
There are many kinds of fluid sources. First, they can be different media such as: compressed air, nitrogen, natural gas, hydraulic fluid, etc. Secondly, they can have various pressures. The third actuator has various sizes to provide output torque.
2. Type of valve When selecting the valve actuator, it is necessary to know the type of valve, so that the correct type of actuator can be selected. Some valves require multi-turn drives, some require single-turn drives, and some require reciprocating drives, which affect the choice of actuator type.
In general, multi-turn pneumatic actuators are more expensive than electric multi-turn actuators, but the reciprocating linear actuator pneumatic actuators are less expensive than electric multi-turn actuators.
3. Torque magnitude For valves with 90 degree rotation, such as ball valve, butterfly valve and plug valve, it is best to obtain the corresponding valve moment size through the valve manufacturer. Most valve manufacturers use the required operating torque to test the valve under the rated pressure. They provide this moment to the customer. The situation is different for multi-turn valves, these valves can be divided into: reciprocating (lifting) movement - stem does not rotate, reciprocating - stem rotation, non-reciprocating - stem rotation, must measure the stem Diameter, stem connection thread size has determined actuator specifications.
4. Selecting the actuator Once the actuator type and the required driving torque of the valve have been determined, it is possible to use the data sheet or selection software provided by the actuator manufacturer for selection. Sometimes the speed and frequency of valve operation need to be considered.
The fluid-driven actuator can adjust the stroke speed, but the electric actuator of the three-phase power supply has only a fixed travel time.
Some small-size DC electric single-turn actuators can adjust the stroke speed.
The four elements that the implementing agency needs to pay attention to
The following elements must be considered when selecting a suitable valve actuator type and specification: