What type of resetting is necessary after the actuation of shutoff devices in an extinguishing system?

The correct answer is manual resetting because, in the context of dry chemical extinguishing systems, once a shutoff device is activated, it typically requires a manual intervention to reset the system before it can be placed back into service. This approach ensures that an operator can assess the situation, confirm that it is safe to reset the system, and perform any necessary checks and maintenance. Manual resetting helps prevent any inadvertent activation and ensures that the problem that triggered the system is adequately addressed before re-engaging the extinguishing mechanism.

Other types of resetting, such as automatic or remote resetting, might sound convenient but can lead to situations where the system is reactivated without confirming the safety of the environment or without addressing the cause of the initial activation. Instantaneous resetting is not practical in cases where a thorough assessment of the operational status is essential. Thus, manual resetting provides a critical step for safety and functional integrity in these systems.