How many outflow valves are on the 737?

How many outflow valves are on the 737?

• A. One Overboard exhaust valve
• B. Two Pressure relief valves
• C. One Negative pressure release valve
• D. One Main outflow valve

Answer: (D)

The system that controls cabin pressure does so by venting air from the cabin to the outside, and this is done through a single primary vent—the main outflow valve. It’s this valve that the cabin pressure controller modulates to maintain the desired cabin altitude and differential pressure. Other valves you might hear about, like pressure relief valves or a negative pressure relief valve, exist for safety: they open only if the system would otherwise experience overpressure or negative pressure, not as the normal vent path. The term overboard exhaust valve isn’t the regular vent used for normal operation on the 737; the main outflow valve handles the required venting. So, there is one outflow valve.

The system that controls cabin pressure does so by venting air from the cabin to the outside, and this is done through a single primary vent—the main outflow valve. It’s this valve that the cabin pressure controller modulates to maintain the desired cabin altitude and differential pressure. Other valves you might hear about, like pressure relief valves or a negative pressure relief valve, exist for safety: they open only if the system would otherwise experience overpressure or negative pressure, not as the normal vent path. The term overboard exhaust valve isn’t the regular vent used for normal operation on the 737; the main outflow valve handles the required venting. So, there is one outflow valve.