Applying Electric Valve Actuators: Needs Assessment

Electric valve actuator (AUMA)

Electric actuators can be found in all varieties of shapes and sizes in waste water treatment plants.  Since the valves to be automated vary in both design and dimension, size consideration and design through an early "needs assessment" is a critical component of the specification process.

Defined as an explicit set of requirements to be satisfied by a material, product, or service, engineers, during this step, will specify what the solution will accomplish, without describing how it will do it.  Specifications usually originate from either design constraints or functional requirements.

As part of the spec requirements and need assessment, these are a number of the questions that engineers should consider, as early in the process as possible, in assessing the needs for a valve actuator.

1. What sort of valve will be needed?  Does the process require linear control valves or rotary quarter turn valves?  This will define the appropriate type of actuator, as well.
2. What is the specification for the actuator sizing? The size will need to match the needed thrust and torque as well as the type of valve.  The efficient actuator, to ensure good valve control, can be neither oversized nor undersized.
3. What are the power requirements, e.g. how much energy will be needed to run the actuator?  Higher voltage actuators use more energy. Low power requirements mean that backup power is more economical.  In most settings, there is a need to save money by running as efficiently as possible, and there are also environmental sustainability hurdles. 
4. Operating Conditions:  Is there severe weather or will the actuator be under water? What is the range of temperatures expected? Keep in mind that not all actuators can work in all conditions.
5. Will the actuator need to run continuously or intermittently? Consider the variation needed in the process. Actuators that have continual modulation are more able to respond to variations in the control requests.
6. Consideration of environmental safety conditions.  What about dust or explosive gases?

Ultimately, the needs assessment will help guide the specification process, with the goal of ensuring how well the final product will perform.  It will pay off to be as detailed as possible during this phase.  Once a needs assessment is finalized, you will be in a better position to specify the right actuator to meet your process requirements.

For more information on specifying electric valve actuators, contact Instrument Specialties by calling 407-324-7800 or visit their web site at http://isi.group

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