Which of the following is NOT a feature of the AFFF system?

The AFFF (Aqueous Film Forming Foam) system is designed primarily for fighting flammable liquid fires and includes several key components that enable it to effectively suppress such fires. A pressure relief valve, while important in many fire protection systems to manage overpressure in piping, is not a standard feature of AFFF systems specifically.

In contrast, a fixed proportioning station is essential because it ensures that the foam concentrate and water are mixed in the correct proportions before application, which is crucial for effective fire suppression. Bilge sprinkling nozzles are also a vital part of the system, as they allow for foam distribution in bilge areas that may have accumulated flammable liquids. AFFF hose stations provide accessible means for firefighters to deploy the foam quickly and efficiently in emergency situations.

Understanding the roles of these components helps clarify why a pressure relief valve is not a typical feature of an AFFF system. The primary focus of AFFF systems is the delivery and application of foam, rather than pressure management, which distinguishes it from other fire protection systems that might utilize relief valves more prominently.