A warehouse fire is not as uncommon as you might think. According to the National Fire Protection Association (NFPA), an average of 1,410 warehouse fires per year were reported in the United States between 2014 and 2018, which equates to about 3-4 warehouse fires a day. This means while you are reading this, a warehouse is dealing with a fire that can potentially cause warehouse damage, injuries, and even loss of life.
| Figure 1. Leading causes of warehouse fires (2014-2018). |
Thanks to the invention of sprinkler systems, most warehouse fires are put out safely. Sprinklers have become one of the most effective ways to reduce the potential for damage and loss of life in a warehouse fire. Luckily, the NFPA provides codes and standards used in over 50 countries, including the USA and Canada, to help facilitate the proper use of sprinklers. When considering fire safety, it’s essential to consider how your racking configuration can also impact the design and implementation of a sprinkler system.
Sprinklers work similarly to faucets in your home, with the difference being that heat causes the water to flow from the sprinkler head. A sprinkler consists of a heat-sensitive glass bulb filled with a glycerin-based liquid that expands when heated. The glass bulb is designed to shatter when it reaches a specified temperature. The plug is released once the glass bulb is shattered, and the water begins pouring down onto the deflector. Directly beneath every sprinkler, you will see a flower-shaped metal device called a deflector. The deflector distributes the water in a specific pattern based on the direction the water needs to be dispersed.
| Figure 2. Sprinkler photo and diagram. |
The first step in determining your warehouse's sprinkler design is to identify the commodity classification of the items being stored. Commodities can be classified between Class I-IV, or Plastics A, B, or C. Plastics have a separate classification due to the high temperatures and speeds at which they burn. Classifying a commodity incorrectly is a costly mistake that can result in an ineffective sprinkler system, which cannot effectively control a fire.
The following questions are an essential starting point in understanding your commodity classification:
Several factors must be considered when integrating a sprinkler system into your racking. The most common sprinkler systems in a warehouse are ceiling and in-rack sprinklers. In some cases, only ceiling sprinklers may be sufficient due to their larger orifice, which releases much larger water droplets that penetrate the fire more deeply than traditional sprinklers. However, ceiling sprinklers must be combined with in-rack sprinklers if the flue space requirements are not met.
| Figure 3. In-rack fire sprinkler system |
| Figure 4. Ceiling fire sprinkler system |
The NFPA defines flue space as the clear vertical floor-to-ceiling openings within rack storage areas. Flue spaces are vital in fire protection since they allow heat to ventilate upward and activate a ceiling sprinkler system much more quickly, allowing water to penetrate throughout the racking system. Not having sufficient flue space can increase the chances of your fire growing horizontally, placing your racking system as a whole and everything stored directly in the line of fire.
| Figure 5. Flue space |
Depending on your specific Authority Having Jurisdiction (AHJ), you must follow specific flue space requirements as building codes vary from place to place. Ideally, flue spaces should be approximately 6 inches wide, depending on the storage height and the type of racking configuration. To learn more about appropriate clearances, refer to our blog about recommended clearances in warehouses.
The need for in-rack fire sprinklers arises when the water penetration from ceiling sprinklers is impeded from reaching the fire anywhere in the system. One solution to consider is to change any solid shelving you might have in your warehouse to wire decking to allow ceiling sprinklers to reach lower levels.
| Figure 6. Waterfall wire decking |
If your warehouse has undergone changes that affect these factors, the effectiveness of the fire protection system may be compromised. The building owner is responsible for identifying where these changes have occurred and informing a fire safety professional so that the fire protection system can be re-evaluated.
Sprinkler design requirements are based on a robust set of fire test data that has established the standard for positioning in-rack sprinklers. Here are a couple of tips to position them properly:
If located in a seismic region, ensure sufficient clearance and protection from the piping and racking components to prevent any damage caused by a seismic event. To ensure the lifespan of a sprinkler system, it is essential to follow proper seismic design guidance using the most recent edition of NFPA 13.
NFPA 13 details the exact clearances needed depending on the nominal diameter of the piping used:
Fire protection can significantly enhance the safety of your building and its occupants if you adhere to the regulations and requirements applicable to your specific region. Some might believe that following these guidelines could cost more money or be too difficult for them to keep up with, but it’s simply not worth gambling with the lives of all those who work inside your facility. According to the NFPA, sprinklers should be inspected annually from the floor level.
Therefore, as a responsible business owner, you should never overlook specific safety protocols. You can start by having your racks assessed by a Damotech engineer. The engineer can identify if your rack configuration is causing any fire protection issues and provide the necessary solutions to ensure compliance with regulations and standards as required by the appropriate authority having jurisdiction. Additionally, our Damotech-engineered rack repair kits offer a seamless and cost-effective alternative to replacing damaged racks, as they eliminate the need to reposition or dismantle your in-rack sprinkler system.