When designing a fire protection system, selecting the right sprinkler system type is one of the most critical decisions. The NFPA 13 Standard for the Installation of Sprinkler Systems defines four primary types of sprinkler systems: wet pipe, dry pipe, preaction, and deluge. Each system has unique characteristics suited to different environments and fire risks. Making the wrong choice can lead to inefficiencies, increased costs, or even compliance issues.

In this guide, we’ll break down the different sprinkler system types, their advantages, and how to determine the best option for your project. If you're new to sprinkler system design, check out our Sprinkler Design article for an overview of the key components involved in fire suppression planning.

Wet Pipe Sprinkler Systems: The Most Common and Reliable Choice

How It Works:

• The sprinkler piping is always filled with water.
• When fire heat reaches a certain temperature, the glass bulb or fusible link inside the sprinkler head breaks, allowing water to flow immediately.

Advantages:

• Most cost-effective and reliable system.
• Immediate water discharge upon activation.
• Simple design with low maintenance requirements.

Best for:

• Offices, hotels, hospitals, schools, and residential buildings where temperatures remain above 40°F (4°C).

Limitations:

• Not suitable for unheated or freezing environments. Water in the pipes could freeze, leading to pipe bursts or system failure.

Dry Pipe Sprinkler Systems: The Solution for Freezing Temperatures

How It Works:

• Pipes are filled with pressurized air or nitrogen, instead of water.
• When a sprinkler head activates, the air is released, causing a pressure drop that opens a dry pipe valve, allowing water to enter the system and flow through the sprinkler.

Advantages:

• Ideal for cold environments where freezing is a concern.
• Prevents pipe bursts caused by frozen water.

Best for:

• Unheated warehouses, parking garages, attics, refrigerated storage, and other spaces that may drop below 40°F (4°C).

Limitations:

• Slight delay in water delivery due to the time needed for the air to release before water can flow.
• More complex and costly than wet pipe systems.

Preaction Sprinkler Systems: Preventing Unintentional Water Damage

How It Works:

• Unlike wet and dry systems, preaction systems require a specific event or combination of events to release water into the pipes before a sprinkler activates.
• There are three types of preaction systems:
  • Non-Interlock: The system fills with water if either a sprinkler head opens or a heat detection system activates.
  • Single Interlock: The system fills with water only when a fire detection device (such as a smoke or heat detector) is triggered.
  • Double Interlock: The system fills with water only when both a fire detection system AND a sprinkler head are activated.

Advantages:

• Reduces the risk of accidental water discharge, making it ideal for environments where water damage must be minimized.
• Double interlock systems are designed for freezer storage where accidental water presence could cause severe damage.

Best for:

• Data centers, museums, archives, libraries, and telecommunications facilities where sensitive equipment or valuable items need protection from accidental sprinkler activation.

Limitations:

• More expensive and complex than wet and dry systems.
• Potential delay in water delivery, especially for double interlock systems.

Deluge Sprinkler Systems: Full Coverage for High-Hazard Areas

How It Works:

• Unlike other systems, all sprinkler heads are open at all times.
• A separate fire detection system (such as heat or smoke detectors) triggers the deluge valve, immediately releasing water from all sprinklers.

Advantages:

• Rapid and widespread water coverage, ideal for fast-spreading fires.
• Often used in combination with foam suppression systems for added fire control.

Best for:

• High-hazard environments include aircraft hangars, chemical plants, power plants, and industrial sites with flammable liquids or combustible materials.

Limitations:

• Not suitable for standard office or residential buildings due to massive water discharge.
• Requires an advanced detection system and higher water supply capacity.

How to Choose the Right Sprinkler System for Your Project

When selecting a sprinkler system type, consider these key factors:

• Building Temperature: If temperatures drop below 40°F (4°C), avoid wet pipe systems and consider dry pipe or preaction systems.
• Water Damage Risk: If water damage is a significant concern, preaction systems (single or double interlock) may be the best choice.
• Response Time Needs: Wet pipe systems provide immediate water discharge, while dry and preaction systems have slight delays.
• Hazard Level: High-risk environments, such as aircraft hangars or flammable liquid storage, often require deluge systems for fast and widespread suppression.

JEM Systems specializes in sprinkler system design and can help you select the right system for your unique needs. Learn more about our approach to sprinkler system design and ensure your fire protection system is optimized for safety and compliance.

Work with an FSSA Member for Top-Quality Fire Protection

At JEM Systems, we take fire protection seriously. As a proud member of the Fire Suppression Systems Association (FSSA), we ensure that our designs follow the highest industry standards, combining expertise, compliance, and innovative technology.

Whether protecting a commercial building, industrial facility, or specialized storage, choosing the right sprinkler system is crucial. Let’s design your fire safety system the right way—contact us today.