What are the fans that are used in negative-pressure ventilation called?

Fans used in negative-pressure ventilation are referred to as smoke ejectors. This method involves creating a lower pressure inside a structure, allowing smoke and heat to be expelled more efficiently through openings in the building. Smoke ejectors are strategically placed to maximize the removal of hazardous smoke, improving visibility for firefighting personnel and enhancing overall safety during operations.

In contrast, the other types of fans mentioned do not serve the same purpose. Hydraulic ventilators are used in specific operations involving water flow, such as directing steam or smoke but are not designed primarily for negative-pressure applications. Pneumatic recirculators focus on circulating air within enclosed spaces and do not create a negative-pressure environment. Positive-pressure fans ensure air is pushed into a structure, enhancing ventilation in a different manner than what is employed in negative-pressure scenarios.