If the third pump is called on automatically in a type 3 system and fails to start, what occurs next?

In a type 3 system, when the third pump is called on automatically and fails to start, the next step is to engage the next pump in the predetermined sequence. This system architecture is designed for reliability and redundancy, ensuring that if one pump fails, the system can continue to function effectively by automatically activating the next available pump. This process helps maintain the required pressure and flow rates needed in the system without interruption.

The approach is inherently proactive, as it prevents a single point of failure from compromising the entire operation. By having a sequential call on the next pump, the system ensures that its operational parameters are preserved, which is critical in water and fuel systems where consistent performance is necessary. This is why engaging the next pump in the sequence is the correct response to a failure in the third pump.

The other choices describe responses that do not align with the operational design of a type 3 system. For instance, the notion of shutting down the entire system or only allowing two pumps to continue running would not be standard practice, as it could lead to inadequate resource availability. Similarly, while alarms and lights may indicate a failure within the system, the immediate corrective action involves activating the next pump rather than just alerting personnel.