Artificially lowering pressure in a structure is an example of what type of ventilation?

Artificially lowering pressure in a structure is an example of what type of ventilation?

• A. Negative ventilation
• B. Positive pressure ventilation
• C. Natural ventilation
• D. Mechanical ventilation

Answer: (A)

Lowering pressure inside a structure relative to the outside is negative pressure ventilation. By exhausting air with a fan or smoke ejector, you create a pressure deficit that pulls in fresh air through openings and also extracts smoke and hot gases. This approach helps control smoke, reduce heat, and create a safer path for entry and rescue. Positive pressure ventilation, in contrast, pushes air into the structure to raise internal pressure and often drives smoke out rather than drawing it away. Natural ventilation depends on wind and buoyancy with no mechanical pressure changes, and mechanical ventilation is a broader term that can involve either negative or positive pressure methods, but the described action specifically corresponds to negative pressure ventilation.

Lowering pressure inside a structure relative to the outside is negative pressure ventilation. By exhausting air with a fan or smoke ejector, you create a pressure deficit that pulls in fresh air through openings and also extracts smoke and hot gases. This approach helps control smoke, reduce heat, and create a safer path for entry and rescue. Positive pressure ventilation, in contrast, pushes air into the structure to raise internal pressure and often drives smoke out rather than drawing it away. Natural ventilation depends on wind and buoyancy with no mechanical pressure changes, and mechanical ventilation is a broader term that can involve either negative or positive pressure methods, but the described action specifically corresponds to negative pressure ventilation.