When inspecting a kitchen hood and duct, which of the following factors is NOT essential to check?

When inspecting a kitchen hood and duct system, the cleanliness of ductwork is essential because grease buildup can create a fire hazard. Regular maintenance and cleaning of the ductwork ensure that there is no accumulation of flammable materials. Additionally, checking the aim of nozzles is crucial to ensure that the extinguishing agent is being properly directed onto cooking surfaces and potential fire sources. The pressure gauge of the extinguishment agent is also a critical component; it indicates whether the fire suppression system is ready to be activated in case of a fire.

On the other hand, the hours of operation, while potentially relevant in understanding usage patterns or predicting maintenance needs, are not directly essential to the physical inspection of the kitchen hood and duct system itself. The primary focus during an inspection revolves around the functionality, cleanliness, and readiness of the fire suppression components rather than tracking how long the system is in use.