Which option is NOT a part of the typical two independent means of ventilation design in B28 systems?

• A. Redundancy to ensure dilution of leaked refrigerant
• B. Identical exhaust locations
• C. Independence of ventilation paths
• D. They can both exhaust to the same area, providing no separate dilution

Answer: (D)

In B28 systems, the ventilation design relies on two independent means to reliably dilute any leaked refrigerant: having redundant paths so air can be moved even if one path is down, and keeping the two ventilation paths independent so they create separate dilution zones and don’t interfere with each other. The idea is to avoid a single point of failure and to ensure that a leak doesn’t accumulate in one area because both paths end up in the same space.

Saying that both ventilation paths exhaust to the same area contradicts that principle. If both paths discharge into the same space, there isn’t true separate dilution for each path, and a leak could achieve a hazardous concentration in that shared area. That’s why that option is not part of the intended two independent means.

The essential aspects—redundancy and independence of the ventilation paths—are what define the typical two independent means in B28 systems.