Which of the following is a requirement for a Dry Pipe System?

The requirement for a Dry Pipe System includes having approved pressure gauges on the water side of the valve. This is important because pressure gauges help monitor and maintain the integrity of the dry pipe system. The dry pipe system functions by keeping water in a standby state, and when the system activates (due to heat from a fire), it allows water to flow into the system from a pressurized source. The presence of approved pressure gauges is essential for ensuring that the valve is functioning correctly and that the system is properly charged with air pressure, which prevents water from entering the pipes until a sprinkler head is activated. This monitoring capability is critical for maintaining system reliability and safety.

The other options do not align with the requirements for a Dry Pipe System. For instance, horizontal sidewall sprinklers are not specifically a requirement and can lead to water trapping issues. Furthermore, Dry Pipe Systems are not installed in all occupancies without regard for hazard classification; they are typically installed in specific environments where the risk of freezing is present. Lastly, a Dry Pipe System indeed requires freezing protection, as the system must be kept at a temperature that prevents the water supply from freezing, which would compromise the operational capacity of the system.