Measuring Exhaust Fan Capacity Before Summer

South Korea’s summer ambient temperatures regularly exceed 32°C in container yards across Chungcheong and Gyeonggi. If your exhaust fan bank was sized for spring conditions, you may discover throttling problems only after the heat arrives.

The Problem with Nameplate CFM Ratings

Exhaust fans mounted on container walls carry manufacturer CFM ratings measured at standard temperature and pressure. At 35°C ambient with intake air already preheated by solar loading on the container roof, actual airflow drops — sometimes by 15–20%. We see this discrepancy on nearly every summer assessment we conduct.

A Field Measurement Protocol

You do not need our equipment to get a preliminary reading. Place a handheld anemometer at each exhaust fan outlet and record airflow velocity. Multiply by the fan opening area to estimate volumetric flow. Compare the total against your container’s heat load: roughly 3.4 CFM per watt of mining equipment at full operation, adjusted upward for summer ambient.

If your measured total falls below 80% of the calculated requirement, plan a fan upgrade or add supplementary exhaust before June.

Intake Side Matters Equally

Operators often focus on exhaust capacity while neglecting intake restriction. Louver screens clogged with pollen, dust, or insect debris reduce intake flow and create negative pressure that pulls hot exhaust air back through gaps in the container shell. Clean intake screens monthly during spring and inspect louver orientation relative to prevailing wind.

When to Call for a Formal Review

If your preliminary measurements show less than 70% of required airflow, or if rack temperatures exceeded 45°C during any test run last summer, a formal cooling and airflow review will identify whether fan upgrades, baffle additions, or intake reconfiguration can solve the problem without replacing hardware.