February 27 2023 0Comment
Preaction valve

What are Pre-Action Fire Sprinkler Systems and Where to use them

Article by Brian Johnstone – Senior Sales Expert –

What are Pre-Action Sprinkler Systems and How Do They Operate

Pre-Action sprinkler systems are essentially dry pipe systems that integrate a separate detection system in order to fill the piping with water. The system piping is normally dry and pressurized with air or nitrogen. The air pressurization is to provide supervision of the piping for leaks. If a leak occurs there will be a trouble alarm sent to the panel but the system will not fill with water. When the detection system (typically electric heat, smoke or flame detection) is activated, the Pre-Action valve will open, thereby allowing the piping to fill with water, then once a sprinkler head opens, water will be applied to the fire.

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Where are Pre-Action Systems Typically Utilized

Pre-Action systems are installed in various occupancies where the accidental discharge of water would create significant hardship and/or a loss of property or equipment. Typical locations for Pre-Action Systems include:

  • Data Centers
  • IT / Computer Rooms
  • Telecommunication Centers
  • Museums
  • Archives
  • Freezer Warehouses

Types of Pre-Action Systems

Single Interlock Pre-Action System. This system is arranged so upon a detection event through the electric detection system the Pre-Action valve will open, then water will fill the piping in advance of the operation of any sprinklers.

Double Interlock Pre-Action System. This system is arranged so two events must happen prior to the piping being filled with water. The electric detection system must activate AND a sprinkler head must open to allow the air or nitrogen to escape prior to the Pre-Action valve opening and filling the piping with water.

Advantages and Disadvantages of Pre-Action Systems

Pre-Action Systems are a great way to provide essential fire protection through the application of water while mitigating potential accidental discharges of water in critical facilities.

Pre-Action Systems are more costly to install and maintain due to their additional complexity, mainly due to the integration of a separate detection system.

Find out if a Pre-Action system is right for your specific application by calling (908)832-5111.

We are happy to answer any questions you may have.