What is Pallet Rack Flue Space?

Nov 25, 2020
pallet rack flue space

Fire safety is a top concern for many material handling organizations. Maintaining correct flue space between your racks can help slow the spread of fire, should one occur in your warehouse.

As warehouse real estate costs rise, it makes more and more sense to squeeze every extra inch of cubic capacity from your buildings. It seems that higher racks and narrower aisles are the standard in modern warehouse design.  

Although increasing density is a smart approach, one area that should never be compromised is the flue space between your pallet racks. The National Fire Protection Association (NFPA) defines flue space as clear vertical lines of sight in rack structures that go from the floor up to the ceiling.

These flue spaces play an integral role in mitigating the spread of fire within a warehouse. Although flue spaces won’t prevent fire, they direct heat and smoke upward if a fire does break out. They also allow fire sprinklers to reach the lower levels of racking.

Flue Space Guidelines

The NFPA defines two types of flue spaces to consider when laying out a pallet rack design for your warehouse:

  • Transverse: If you are looking at the rack system face, this is the space between the pallets being stored parallel to the direction of loading.
  • Longitudinal: If you are standing at the end of the row of racking, this is the space between each back-to-back row of pallet rack perpendicular to the direction of loading.

The minimum requirement longitudinal flue space is six inches of unobstructed opening from the top to the bottom of the racks, meaning that back to back pallet racks must have at least six inches of clear space between them. Remember that you must account for pallet overhang, so typical designs use 12” row spacers that allow for 3” overhangs on both rows of racks. 

The transverse minimum requirement is three inches. This means that pallets need to be spaced 3” from an upright, and adjacent pallets must be 3” apart. 

Although these are the NFPA specifications, check your local fire code to make sure you’re in compliance with any additional state or local regulations. 

How To Keep Your Flue Space Clear

 To maintain safety compliance guidelines, there can be no obstructions in your 3” transverse or 6” longitudinal flue spaces.  If pallets get pushed too far back when loaded on a rack, this can quickly become a problem.  There are several ways to prevent pallet push-through, including:

  • Rack Straps- These are mounted on the back of each bay and prevent pallets from traveling back into the flue space.
  • Pallet Stop Beams- These beams are fastened to uprights 6-12” above the beam level to prevent pallets from being pushed back into the flue space.
  • Wire Rack Backing- Although these are primarily designed to keep items from falling into aisles, they can also be used backstop pallets so they don’t encroach on flue space.

Talk To A Rack Safety Expert

 If you’d like to learn more about warehouse fire safety practices, or have questions about local code compliance, get in touch with a pallet rack expert at Raymond West today.