If the dry system serves a freezer, how much time is allowed for refilling to normal air pressure?

The correct choice indicates that if a dry pipe sprinkler system is serving a freezer, a time allowance of 60 minutes is established for refilling to normal air pressure after a discharge. This is important because maintaining the appropriate air pressure is crucial for the system’s functionality, especially in environments like a freezer where the temperature is low and could lead to freezing issues if water were to sit in the pipes.

The 60-minute timeframe allows for a safe and efficient refill that helps to ensure the system can reinstate its protective functions properly. It accounts for factors such as the low temperatures that might affect pressure restoration and the operational efficiency needed to manage any potential fire risks in such environments.

The other timeframes allow for either too short or too long durations, which may not be practical or safe in terms of achieving the necessary pressure restoration in a timely manner. By requiring 60 minutes, the code aims to balance safety and efficiency effectively for systems located in chilling conditions.