Flue Space Illustrated

Why Have Flue Space Between Your Pallet Racks?

Flue space is a small but essential part of fire safety for your warehousing operations. Flue space is defined by the National Fire Protection Association (NFPA) as clear vertical lines of sight in the rack storage areas that go from the floor up to the ceiling.


The flue space on a pallet rack will not prevent a fire, but in the event of a fire, it will send heat and smoke upward to help keep the fire from spreading throughout the building.


How Does Flue Space Work?


There are two different types of flue space; these include:


Flue Space IllustratedTraverse flue space- As you stand in front of the racks this is the left to right flue space between rack upright and the pallet as well as the left to right flue space between the pallets loaded on the rack.

Longitudinal flue space- This is the space located between back to back rows of pallet racking. This space has a width that should not exceed 24 inches between the product stored on the rack.


If a fire occurs, the flue space provides space for the fire to vent upward rather than across multiple pallet racks, helping to delay the spread of the fire. The theory behind the flue space is that by venting the fire upward the flue helps contain the fire to a confined space. This allows the sprinkler systems to extinguish the flames or keep them from spreading until firefighters arrive.


Flue Space Guidelines


The National Fire Protection Association sets flue space guidelines for pallet racks. The guidelines they set are for minimum flue space but be sure to check your local building codes because they can differ slightly.


Flue space is required for all pallet racks that have storage for single, double, or multiple rows of pallets that are 25 feet or higher.


The minimum flue space requirement for longitudinal flue is six inches of clear opening from the top to the bottom of the racks, meaning six inches of clear space between back to back rows of pallet racks. The traverse minimum requirement is three inches. For each type of flue space, there must be no obstructions.


Keeping Flue Space Clear


Pallet-push through is one of the most common ways that longitudinal flue space can become blocked. This can be prevented in a variety of ways, including:


Pallet Stop Beams- These beams easily snap or bolt into the rack uprights 6” to 12” above the beam level to stop the pallets from being pushed back into the flue space.

Rack Straps- These are attached to the back of each bay and stop the pallets from being pushed back into the flue space.

Wire Rack Backing- These are also installed on the back of the row of rack. They are typically  used to prevent items store on the pallets from falling off the back of the racks into aisles but can also be used to restrain loads from blocking the flue space.


Wide Variety of Pallet Racks and Warehouse Safety Products


Cranston Material Handling of Pittsburgh offers a variety of safety products and pallet racking options to meet the needs of your operations. Contact us today to learn more about how we can help you maximize your space and create a safer environment for your employees.