Pressure delivered by the face-mounted regulator

Pressure delivered by the face-mounted regulator

• A. 1 psi
• B. 0 psi
• C. 5 psi
• D. 3 psi positive pressure

Answer: (D)

A face-mounted regulator is designed to keep the inside of the facepiece slightly pressurized compared with the surrounding air. That small positive pressure helps prevent airborne contaminants from leaking into the mask around the seal and makes breathing easier for the wearer by ensuring air is readily available when you inhale. The value used in practice is about 3 psi above ambient, which is enough to maintain that protective overpressure without making breathing effort uncomfortable. If the pressure were zero, contaminants could seep in; a much lower or higher pressure than this typical value would either undermine protection or feel less comfortable, so 3 psi positive pressure best matches how the device is intended to operate.

A face-mounted regulator is designed to keep the inside of the facepiece slightly pressurized compared with the surrounding air. That small positive pressure helps prevent airborne contaminants from leaking into the mask around the seal and makes breathing easier for the wearer by ensuring air is readily available when you inhale. The value used in practice is about 3 psi above ambient, which is enough to maintain that protective overpressure without making breathing effort uncomfortable. If the pressure were zero, contaminants could seep in; a much lower or higher pressure than this typical value would either undermine protection or feel less comfortable, so 3 psi positive pressure best matches how the device is intended to operate.