Measuring Proper Airflow Across Single Board Computer
The product specification for Single Board Computers (SBC) dictates a minimum air flow in order for the SBC to meet the maximum specified Operating Temperature. This is specified in LFM, Linear Feet per minute. It is often necessary to measure the LFM to determine if a chassis fans are providing adequate air flow. Fans are typically rated in CFM, Cubic Feet Per Minute. The air flow can be measured with a Air flow meter. It typically has a wand type probe that you hold over the point that you want to measure.
The airflow must be measured in the correct location to make sure that there is proper flow. In a vertical chassis, it is recommended to have the fans mounted beneath the chassis. Airflow is recommended to be pushed across the SBC's heat sink. The correct place to measure is directly above the heat sink where the air exits the chassis. In order to maximize airflow in a chassis, all Open slots should be covered. Due to the different heights of the components mounted on a SBC board, the air will meet with varying resistance as it flows across the board. Therefore, it is critical that the minimum air flow specification is met if the board is intended to operate in an environment which has maximum specified temperatures. Chassis which pull air across the SBC are very critical to be measured. They have a tendency to not provide adequate airflow.