Which of the following actions is not affected by a fail-safe system?

The concept of a fail-safe system is designed to ensure safety by preventing hazardous conditions or shutting down processes in the event of a failure. In this context, normal flow in a closed system typically refers to the intended operation of a system that functions as designed without any anomalies. Since a fail-safe system is established to react to faults or malfunctions, normal flow does not fall under the sphere of actions that a fail-safe would need to address.

In contrast, situations such as flow from a ruptured pipe, pressure buildup in a container, and accidental release of vapors represent potential failure scenarios. These require automatic interventions by a fail-safe system to mitigate risks, such as shutting down the system or venting pressure, to ensure safety and prevent accidents. Therefore, the action of maintaining normal flow is inherently stable and does not necessitate fail-safe interventions. Understanding the operational distinctions between normal conditions and failure scenarios plays a crucial role in the application of safety measures in laboratory settings.