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Wet vs Dry Sprinkler System – NY Engineers

Written by Keith Fink | 10/24/24 1:00 PM

When it comes to fire protection, the choice of sprinkler system can make all the difference. Property managers, building owners, and fire safety professionals know that selecting the right system is crucial to ensuring safety and compliance. But with options like dry and wet sprinkler systems, how do you decide which provides the most efficient protection? This guide will explore each system's differences, benefits, and ideal applications to help you make an informed decision.

What is a Wet Pipe Sprinkler System?

Wet pipe sprinkler systems are the most traditional and commonly used type in buildings around the world. These systems are characterized by their simplicity and effectiveness, making them a go-to choice for many property managers and building owners. In a wet pipe system, the sprinkler pipes are constantly filled with pressurized water, ready to spring into action at a moment's notice.

As per a recent study, The U.S. fire sprinkler market was valued at $3.41 billion in 2023 and is expected to grow to $3.53 billion in 2024, reaching $5.71 billion by 2032.

How Do Wet Pipe Sprinklers Work?

Wet pipe sprinklers are a common fire protection system that operates by utilizing a network of pipes filled with water. When a fire is detected, the heat activates a heat-sensitive element in the sprinkler head, which opens and releases water directly onto the flames. This immediate response helps to suppress the fire and prevent its spread. Wet pipe systems are favored for their reliability and efficiency, as they provide automatic coverage without the need for external activation. They are particularly effective in areas where temperatures remain above freezing, ensuring the water in the pipes doesn't freeze.

Components of Wet Pipe Sprinkler System -

1. Water Supply

The system is connected to a reliable water source. The pipes are always filled with water, ensuring immediate discharge when a fire is detected. This readiness is key to the system's effectiveness.

2. Sprinkler Heads

Each sprinkler head contains a glass bulb or fusible link. This component acts as a seal, keeping water in place until needed. The integrity of this seal is crucial to prevent accidental discharge.

3. Fire Detection

When a fire breaks out, the heat causes the glass bulb or fusible link to break. This allows water to flow directly onto the affected area, suppressing the fire quickly and effectively.

4. Fire Suppression

The immediate release of water helps cool the flames and stop them from spreading. This rapid response can be the difference between a minor incident and a major disaster.

Common Applications of Wet Pipe Sprinklers

Wet pipe systems are versatile and suitable for a variety of environments. They are often installed in:

  • Apartment buildings
  • Office buildings
  • Hotels
  • Retail stores
  • Entertainment centers
  • Nursing homes

What is a Dry Pipe Fire Sprinkler System?

Dry pipe systems differ fundamentally from their wet counterparts. In these systems, the sprinkler pipes are filled with pressurized air or nitrogen rather than water. The water is held back by a dry pipe valve, preventing it from entering the pipes until it is truly needed.

As per recent report, The residential segment of the fire sprinkler systems market is expected to expand at a CAGR of over 9% between 2024 and 2032.

How Do Dry Pipe Sprinklers Work?

Dry pipe sprinklers are designed for environments prone to freezing, where traditional wet pipe systems might fail. In a dry pipe system, the pipes are filled with compressed air or nitrogen instead of water. When a fire occurs and activates one or more sprinklers, the air is released, causing a drop in pressure. This action opens a valve, allowing water to flow into the pipes and out through the open sprinkler heads.

This system is advantageous in cold areas as it prevents water from freezing and causing pipe bursts. However, it takes slightly longer to deliver water to the fire compared to wet pipe systems.

Components of dry pipe sprinkler system -
1. Pressurized Air

The pipes are filled with air or nitrogen, maintaining pressure that holds the dry pipe valve shut. This prevents water from sitting in the pipes, eliminating the risk of freezing in cold temperatures.

2. Fire Detection

When a fire is detected, the heat reduces the air pressure in the pipes. This pressure drop triggers the system's response, allowing water to flow through.

3. Valve Opens

The reduction in air pressure causes the valve to open. Water then flows into the pipes and is discharged through the sprinkler heads to extinguish the fire.

Common Applications of Dry Pipe Sprinkler Systems

Dry pipe systems are ideal for areas where freezing temperatures could pose a risk to traditional wet pipe systems. They're commonly used in:

  • Unheated warehouses
  • Parking garages
  • Cold storage facilities
  • Loading docks
  • Outdoor canopies
  • Remote storage units

These environments benefit from the dry pipe system's ability to protect against freezing, ensuring reliable operation even in the coldest conditions.

Comparing Wet and Dry Fire Sprinkler Systems

Wet Pipe Sprinklers

Wet pipe systems are the most common and traditional type of fire sprinkler system. Their advantages include:

Pros:

  • Simplicity in design, making them easy to install and maintain
  • Immediate response due to water being pre-filled in the pipes
  • High effectiveness in various applications

Cons:

  • Pipes may freeze in colder temperatures, potentially causing system failure
  • Risk of water damage if there is a leak in the pipes
Dry Pipe Sprinklers

Dry pipe systems offer a different approach, with their own set of advantages:

Pros:

  • Resistant to freezing, making them suitable for cold environments
  • Can be used in conjunction with wet systems to provide comprehensive coverage

Cons:

  • More complex and costly to maintain
  • Longer response time due to water needing to fill the pipes before discharge
Feature Wet Pipe Sprinkler System Dry Pipe Sprinkler System
Pros    
Simplicity Simple design with fewer components, easier to install and maintain. More complex, but still a proven and effective system.
Response Time Immediate water discharge upon fire detection, ensuring fast response. Slight delay in water release as pipes are filled with air.
Cost Generally more cost-effective to install and maintain. Higher installation costs due to more components and complexity.
Maintenance Lower maintenance requirements due to fewer parts and no air-filled pipes. Requires regular maintenance to ensure air pressure and valve operation.
Reliability Highly reliable with fewer parts that can malfunction. Reliable in cold environments where water-filled pipes would freeze.
Water Readiness Pipes are filled with water at all times, making it instantly ready for use. Water is held back until the system activates.
Cons    
Freeze Risk Not suitable for environments exposed to freezing temperatures. Ideal for environments where pipes could freeze.
Installation Limited to spaces where freezing isn’t a concern. More complex installation and higher cost.
System Size Limitations Less effective in larger buildings where long pipe runs can slow water delivery. More suitable for larger or unheated spaces.

Key Takeaways from Our Design Experiences

For wet pipe sprinkler System

1. Water pressure level

  • Minimum (Min): The lowest acceptable pressure level, which in this case is 7 psi.
  • Maximum (Max): The highest allowable pressure level, which in this case is 12 psi.

2. Minimum pipe diameter should be 1 inch

3. The materials used for wet pipe sprinkler systems include carbon steel and chlorinated polyvinyl chloride.

For Dry pipe sprinkler System

1. Dry sprinkler systems are usually filled with nitrogen and compressed air.

2. As per NFPA 13, the slope for dry pipe sprinkler systems is 1/4 inch per 10 linear feet for mains and 1/2 inch per 10 linear feet for branch lines.

3. A compressor is essential for a dry pipe sprinkler system, as it supplies the pressurized air needed to keep the dry valve closed until a fire triggers the sprinkler heads. According to NFPA 13 standards, this pressurized air must be continuously maintained by a dedicated compressor equipped with an air maintenance device (AMD). This ensures the system remains ready for activation when required, effectively providing fire protection without the risk of water in the pipes freezing.

Conclusion

Choosing the right sprinkler system is pivotal to ensuring effective fire protection and compliance with safety regulations. Wet pipe systems offer simplicity and immediate response, ideal for environments where freezing is not a concern. Conversely, dry pipe systems provide protection against freezing, making them suitable for colder areas or outdoor installations.

Ultimately, the decision between dry and wet sprinkler systems should be based on the specific needs of your building, environmental conditions, and budget. Consider consulting with fire safety professionals or engineers at NY Engineers to design a custom fire protection solution that addresses your unique requirements.

Remember, investing in the right fire protection system not only safeguards property and lives but also offers peace of mind. For more insights on fire safety or to explore custom solutions, consider reaching out to expert fire protection consultants who can guide you in selecting the optimal system for your needs.