What is the most common type of fire-sprinkler system?

• A. Dry pipe system
• B. Wet pipe system
• C. Deluge system
• D. Wet-Dry Hybrid System

Answer: (B)

The key idea here is that the simplest, most reliable option for everyday fire protection is a system where the piping is filled with water at all times and the water goes directly to the sprinkler head that’s activated. In a wet pipe setup, when a sprinkler head is triggered, water is released immediately through that head because the pipes themselves already hold water. This immediate response, combined with fewer parts that can fail and a lower upfront and maintenance cost, makes it the most practical choice for most buildings.

Dry pipe systems, with pipes filled with pressurized air or nitrogen and water held back by a dry valve, introduce a delay as water has to travel through the dry pipe to reach the sprinklers. They’re more complex and costlier to install and maintain, and their water delivery is slower, which is less desirable for ordinary occupancy.

Deluge systems supply water to all sprinklers simultaneously because all heads are open, which means much higher water flow and greater waste—appropriate only for specific high-hazard areas, not typical buildings.

Wet-dry hybrid systems mix features and serve specialized needs, so they’re not the standard choice in most settings.

So, the most common type is wet pipe because it provides immediate water to the affected area with a straightforward, cost-effective design.