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Reversible Flow Fans Feature Directional Flow and Speed Control in One Unit

Previously, if the designer wanted to achieve two directions of airflow, two fans would be required.

Orion Fans
Orion Fans

Orion Fans (Dallas, TX) has launched a series of microcontroller-based, up to IP68-rated, reversible flow fans. By utilizing PWM signals to control fan speed, the fans provide engineers a solution to some of their most challenging cooling requirements: speed and airflow direction controlled by one fan without supplementing excess wires or circuitry. 

Previously, if the designer wanted to achieve two directions of airflow, two fans would be required. This arrangement added cost to the bill of materials, required more area in the design to accommodate both fans, increased maintenance requirements and lowered product reliability. 

Reversible flow fans are a specialty design that enables some unique use cases:

  • Outdoor applications where the device intakes air in one direction, but a periodic reverse flow ensures air pathways do not become clogged with environmental debris
  • Equipment where seasonal environmental changes require different airflow of intaking versus exhausting air
  • Situations where a “confidence check” is needed to confirm the proper operation of airflow monitoring sensors
  • Applications where dynamic control of airflow pathways is needed and large airflow check valves may be difficult or impossible to integrate
  • HVAC applications where occasional intake of environmental air is required to comply with building codes
  • Other applications include vending machines, cooler display cases and lighting

In typical fan speed control, PWM control provides a fixed-frequency AC square wave signal to the fan and the duty cycle of the waveform is altered to match the desired speed. Reversible fans extend this control paradigm by segmenting the PWM duty cycle curve into “Forward” versus “Reverse” regions.

This segmentation still allows for speed control over a condensed duty cycle range, while enabling control of the direction of flow without requiring additional control wires or circuitry.

In most cases, a simple firmware or software change in the customer’s equipment facilitates direction control with minimal disruption of industry standard control assumptions.

The reversible flow fans are currently available in 120mm and 172mm packages, in 12V, 24V, 48V and 60V versions. Pricing starts at $30 in small quantities.

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