What is the necessary condition for performing PDIs on the torch?

The necessary condition for performing PDIs (Pre-Departure Inspections) on the torch relates to the stowage, quantity, and flash interval of the device. This aspect ensures that the torches are not only adequately stored in appropriate locations but also that there are enough units available for emergency situations and that they meet specific operational standards, such as flash intervals to confirm they are functioning properly.

Proper stowage is crucial because it ensures that the torches can be accessed quickly when needed. Quantity is equally important, as having multiple units ensures that the crew has sufficient tools for diverse situations. The flash interval is a vital characteristic that verifies the torch's operational status, ensuring that it can provide reliable lighting during emergencies.

Each of the other options, while important to fire safety and emergency preparedness, do not specifically align with the criteria needed to ensure that PDIs on the torch can be effectively conducted. Proper lighting conditions and the presence of smoke and fire pertain to situational awareness but do not directly impact the inspection procedures. Testing battery life and functionality is a crucial component of maintenance but is not a standalone condition for performing PDIs specifically.