What altitude is the maximum difference for the pressure relief valves in the pressurization system of a 737-800?

The maximum difference for the pressure relief valves in the pressurization system of a Boeing 737-800 is 9.1 psi. This specification is crucial because the pressure relief valves play a vital role in maintaining cabin pressure within safe limits during flight. The set pressure difference ensures that in the event of an excessive cabin pressure situation, the relief valves will open at the appropriate pressure levels to prevent structural damage to the aircraft or unsafe operating conditions for passengers and crew.

Understanding this value is particularly important during the climb and descent phases of flight, where pressure changes can be most pronounced. By having a set maximum difference for these valves, aircraft design ensures a balance between safety and operational performance. The specific number of 9.1 psi reflects the engineering standards and safety practices that guide aircraft pressurization systems.