Final answer:
The correct answer is option 4: The system must be able to run without the isolated equipment. Isolation allows for maintenance and safety without disrupting system operations, and is key in industrial systems, power plants, and laboratories.
Step-by-step explanation:
The correct answer is option 4: The system must be able to run without it. When a piece of equipment can be isolated as a separate unit in a system, it means that the overall system's functionality is retained without the operation of that isolated unit. The concept of equipment isolation is crucial for maintenance, safety, and operational flexibility. In the context of industrial systems such as those involving gases, water, or hydraulic systems, being able to isolate components without affecting the rest of the system allows for safe repairs, upgrades, or replacement of the equipment.
Systems like power plants or laboratories are designed with this redundancy or modularity in mind to ensure ongoing operations during such events.
Safety devices like gauges, circuit breakers, and ground fault interrupters are typically present for monitoring conditions and ensuring safety, but the ability to run without a particular piece of equipment is the key indicator that it can be isolated as a separate unit.