Positive ventilation is defined as which configuration?

Positive ventilation is defined as which configuration?

• A. Exhaust off/low, supply high in surrounding areas
• B. Exhaust off, supply low in surrounding areas
• C. Exhaust high, supply low in affected space
• D. Exhaust high, supply high in surrounding areas

Answer: (A)

Positive ventilation aims to keep contaminants out by creating a higher pressure inside the protected space than in the surrounding areas. This is done by pushing in a lot of air (high supply) while keeping the outflow (exhaust) minimal, so the pressure builds rather than being relieved. That’s why a setup with exhaust off or low and a strong supply is the configuration that achieves positive pressure. If exhaust were high or supply was low, the space wouldn’t maintain a positive pressure differential, and contaminants could still enter. Supplying air to surrounding areas without building pressure in the protected space wouldn’t achieve the desired protective effect either.

Positive ventilation aims to keep contaminants out by creating a higher pressure inside the protected space than in the surrounding areas. This is done by pushing in a lot of air (high supply) while keeping the outflow (exhaust) minimal, so the pressure builds rather than being relieved. That’s why a setup with exhaust off or low and a strong supply is the configuration that achieves positive pressure. If exhaust were high or supply was low, the space wouldn’t maintain a positive pressure differential, and contaminants could still enter. Supplying air to surrounding areas without building pressure in the protected space wouldn’t achieve the desired protective effect either.