How to Select Damper Actuators
Damper actuators are powered devices that are used to operate a damper and adjust the flow of air and smoke. There are two basic types: electric and pneumatic. Electric damper actuators differ in terms of output. Choices include 0 to 12 VDC, 2 to 10 VDC, and 4-20 mA. Products with features such as low-power consumption, direct action, reverse action, and thermal protection are commonly available. Pneumatic damper actuators have a start point that is measured in pounds per square inch (psi). The span is a direct function of a feedback spring. In some products, the spring is designed to provide equal force on both the power and return strokes. General damper actuators and specialized fire and smoke damper actuators are also available.
Selecting damper actuators requires an analysis of product specifications. Parameters include torque, supply voltage, and operating. Torque, the required range of output, is often measured in inch-pounds (in-lbs). For a single force, torque or moment of force is the cross-product of a vector from a reference point to the application point. For multiple forces, torque is the vector sum of the torque values for each of the forces. Supply voltage is the nominal voltage supplied to motor of the damper actuator. Operating temperature is measured in degrees Fahrenheit or degrees Celsius and indicates the full required range of ambient temperatures for damper actuators.
Damper actuators carry specifications for shaft diameter and position feedback. Shaft diameter is usually measured in inches, and indicates the diameter of either the output shaft or the table. Damper actuators with angular position-feedback incorporate devices such as encoders or potentiometers. Encoders are devices that are used to change a signal or data into code. Types include linear, digital, incremental rotary, and absolute rotary. Potentiometers are passive electronic components that oppose the flow of either alternating current (AC) or direct current (DC). Types for damper actuators include linear and digital.
Certifications and Approvals
Damper actuators differ in terms of certifications and approvals. Choices include the CSA Mark and the UL Mark. Damper actuators that bear a CSA Mark have been tested by the Canadian Standards Association (CSA) and meet applicable standards for safety and/or performance. The UL Listing Mark indicates that Underwriters Laboratories Inc. (UL) has determined that representative samples of damper actuators meet UL's safety requirements. These requirements are primarily based on UL's own published Standards for Safety.