How Does a Pre-Action Sprinkler System Work?

How Does a Pre-Action Sprinkler System Work?

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How Does a Pre-Action Sprinkler System Work?

What is a Pre-Action Sprinkler System? In this article, we’ll look just at the three types of sprinkler systems. These include Wet pipe, Non-interlock, and Dry chemical systems. But how does one of these systems work? And which type is right for your building? Here’s a closer look. Listed below are the some of the main components of a Pre-Action system.

How Does a Pre-Action Sprinkler System Work?

Wet pipe

Wet pipe in a pre-action sprinkler system is an option for most buildings. These systems use pressurized air or nitrogen in place of water, and when the sprinkler head triggers, it opens. 

However, this type of system has its drawbacks, including delayed response time and more maintenance requirements. Another disadvantage is that dry pipe sprinkler systems are more susceptible to corrosion. The compressed air creates an enticing environment for the corrosion of sprinkler piping.

The double interlock pre-action system prevents accidental water entry into a building without the sprinklers. These systems are typically used in freezer facilities where accidental water entry could lead to expensive remediation. However, one disadvantage of double-interlock pre-action systems is the slower response time. They require a complex setup and a high cost. In addition, they are less efficient than single-interlock systems.

Regarding fire safety, pre-action sprinkler systems are the best option for warehouses and freezers. In addition to preventing accidental discharge, they also have the highest fire protection performance. However, they are some more complex and expensive to install and require more maintenance. 

They often contain pressurized nitrogen or air. The most common application for pre-action systems is in freezer warehouses. If you’re looking to install one, contact a sprinkler installation professional today!

Wet pipe in a pre-action sprinkler system is the most effective option for buildings that have water-sensitive properties. For example, cold storage warehouses present unique challenges regarding fire protection. Accidental discharge of water would immediately freeze, creating a costly problem. However, pre-action systems provide the best solution for valuable properties. Regular maintenance of your sprinkler system is essential to protect your investment.

Another option for pre-action sprinkler systems is the deluge suppression system. On the other hand, a deluge suppression system relies on compressed air as a fire extinguishing agent. For this, a wet pipe system uses nitrogen or pressurized air to suppress the fire. Dry pipe systems are also used in combination with a dry system. A separate dry system is connected to a wet pipe system and a dry valve in both systems.


A non-interlocking sprinkler system allows water to be admitted to a fire only when detection devices open. However, a double-interlocking system is intended for sensitive spaces, such as freezer storage warehouses, and is more expensive. It also delays water delivery and could result in a more significant portion of the building being involved. In these situations, a single-interlock system may be better. This article outlines the benefits of both types of systems and their advantages.

The main advantage of a non-interlocking sprinkler system is the ease of installation. In addition, this type of system can work in combination with pre-action systems because it requires fewer piping and detection devices. However, the disadvantages of a non-interlocking system include high material and installation costs and many working parts. As a result, it is essential to choose the right sprinkler system for your building and where you’ll be using it.

A non-interlocking sprinkler system is a good option if the area’s temperature is low and you’re worried about false alarms. The supplemental detection device will activate the sprinkler valve when a fire reaches a higher temperature than can be controlled with a dry valve. This prevents the accidental discharge of water, which could harm sensitive items. This type of sprinkler system is expensive, but it does offer superior protection.

A single-interlock system is similar to a dry pipe system. Still, it requires a fire detection event before water can enter the system. This is often achieved through smoke or heat detectors. Once a fire detection event occurs, the mechanically latched valve opens, and water is released. This system is considered a pre-action system, and it reduces the time needed to deliver water to the fire.

A dry-pipe system relies on pressurized air or nitrogen to activate the sprinkler head. Because of the delay in response, a dry-pipe system is slow to respond to a fire. It also requires more maintenance and is prone to corrosion. It also has a higher chance of rusting sprinkler components due to the compressed air. If the system is not installed correctly, water damage can be extensive and expensive.

Dry chemical

A dry chemical in a pre-action sprinkler system uses a dry powder to suppress fires. The most common types of dry chemicals are sodium bicarbonate and mono-ammonium phosphate. The powder is released from a pressurized tank through a valve opened by a high-pressure nitrogen cartridge. Once the dry chemical is released, it must be recharged before it can be used again.

A dry chemical is an explosive compound that acts as a fire suppressant when applied to a fire. Its composition must comply with NFPA 17 and NFPA 33 standards for applying flammable materials. There are also specific requirements for a dry chemical in a pre-action sprinkler system, such as UL 1254. The Authority Having the Jurisdiction, or AHJ, is the best source for interpreting these standards.

Another type of dry chemical in a pre-action sprinkler system is nitrogen generators. The use of nitrogen allows system piping to dry, and it has a low dew point. As with any fire suppression system, it is essential to consider the use of an early-warning fire-detection system as well. The following information will explain the benefits of dry chemicals in pre-action sprinkler systems.

The benefits of pre-action systems outweigh their disadvantages. These systems may not respond effectively when a fire occurs. The sprinkler heads may falsely activate, resulting in expensive property damage and irreversible water damage. A two-event discharge requirement further elevates the protection provided by a pre-action sprinkler system. Moreover, the use of pressurized air can detect leaks.

Inert gas

When selecting a fire suppression system, consider the risk exposure to your business, budget, and building code. For example, halocarbons are considered a clean agent and are used to extinguish electrical fires. However, they can also harm people and damage equipment. Instead of Halon, you should consider inert gases, which suffocate fires. These gasses can also be used in combination with water systems.

When using an inert gas, you can choose to use nitrogen or both. The generator’s nitrogen gas generated is at least 99.9 percent pure and contains no more than 0.5 percent oxygen. In addition, if you choose to use a nitrogen generator, you can use a vent to purge the oxygen. This makes the gas safer and allows you to install it quickly and easily.

The use of gaseous fire-suppression systems is associated with high-tech applications. Halon 1301 was king of the commercial fire-suppression market in the 1980s. Still, the Montreal Protocol halted the use of gas in these applications. As a result, loss-prevention managers scrambled to find an alternative. Pre-action sprinkler systems were chosen. These systems require that a fire alarm be activated before the water pipe operates.

Consequently, they are more effective in preventing massive amounts of water damage. Pre-action systems should be vented continuously to prevent MIC. The exhaust gas will carry trapped water out of the system and keep the sprinkler system free of solids that could feed bacteria. In addition, it is recommended that you have the sprinkler system inspected every five years as per NFPA 25. You can choose from pipe-shield coating inside the sprinkler pipes or pressurized nitrogen to pressurize them for corrosion protection.

Pre-action sprinkler systems have several advantages. The fire detection valve will open when temperatures rise to 125° or more. This will release pressurized air to suppress the fire and prevent it from spreading. Unlike conventional fire sprinkler systems, this fire suppression system prevents water from damaging equipment in the data center. You can also use pressurized air to detect leaks before the water starts flowing.