What is the consequence of not using a blanking panel in a densely populated rack?

• A. Increases impedance and degrades signal quality.
• B. Recirculation of hot air to the cold aisle.
• C. No effect.
• D. Increases power efficiency.

Answer: (B)

Blocking the gaps above and around equipment in a densely populated rack keeps hot exhaust from mixing with the cold supply air. In a hot aisle/cold aisle setup, cold air is meant to flow to the fronts of servers, while hot air is exhausted out the backs. Without a blanking panel, the warm air exiting the back of one device can slip forward or circulate inside the rack and be drawn into the intakes of other devices, sending hot air into the cold aisle. This recirculation raises the intake temperatures for the equipment, reduces cooling efficiency, and makes the cooling system work harder. Blank panels close those gaps, preserving the intended separation of hot and cold air streams.