An Answer to the Clogged Filter Syndrome

For years, engineers have been struggling to find a way around the clogged filter syndrome, which ultimately reduces the cooling efficiency of their product and may cause premature system failures. What we propose is a methodology by which the filter system's porosity may be constantly monitored and automatically compensated for by checking total system temperature. This method will also supply an alarm to the system should the temperature exceed a norm, as caused by clogged filters or other electrical malfunctions. Comair Rotron's Therma Pro-V products incorporating Fan Performance Sensing (FPS) can be configured to achieve this goal.

Traditionally, the Fan Performance Sensor option has been set to detect a reduction in fan speed, typically 50% of rated operation but let's reverse the thought process and suggest a condition in which the fail point is one approaching full performance (rotational speed). Next, the fans to be selected will incorporate the thermal sensing option. In this mode, the fan at room (ambient) temperatures will be running at a much slower rate, for example 2100 RPM (versus 3300 for full speed), producing quiet, efficient cooling to the system. Should the ambient temperature within the system or outside the system rise, the speed of the fan will increase proportionally. If the temperature exceeds the high speed fail point determined by the FPS trip point and the internal temperature, lets say 2800 RPM or 40°C, an alarm function will be initiated. With this in place, we can analyze the filter systems detection capability. Again, at 25°C, the fan will be operating at 2100 RPM. As the filter system becomes clogged, airflow will be impeded and internal system temperatures will start to increase. As this occurs, the fan speed will automatically increase to compensate for the increased filter impedance to maintain necessary cooling. However, at some point the filter will become severely blocked and the fan no longer will be able to maintain acceptable cooling. Internal temperatures will now have risen to approximately 40°C and fan speed will increase until the 2800 RPM threshold has been reached, initiating the alarm function. The actual RPM to temperature values given are for reference only and may be modified to meet specific applications. We believe we have finally achieved an acceptable, cost-effective way to overcome the CLOGGED FILTER SYNDROME.