Which component is unnecessary in a safe NH3 system?

In a safe ammonia (NH3) system, a fume hood is not typically considered a necessary component for the core operation and safety of the system itself. While fume hoods are excellent for controlling exposure to hazardous fumes in laboratory settings, their application is not as critical specifically within the context of a high-pressure ammonia system.

The primary purpose of a fume hood is to provide ventilation and protect personnel from inhaling toxic vapors. In industrial applications where ammonia is handled, other safety devices and systems—such as safety valves, pressure sensors, and high-temperature alarms—are essential for monitoring and controlling the system's operation, preventing overpressure situations, and ensuring that temperature limits are adhered to. These components directly contribute to the safety and integrity of the ammonia system.

Therefore, while fume hoods can enhance safety in specific environments, they are not essential for the operation of ammonia systems designed for high-pressure applications. This is why a fume hood is deemed unnecessary in this context.