Pallet Rack Flue Space: What It Is and What It Does

We are barely into 2018 and the list of fires has started. Warehouse fires in Moreau, New York, Sumter, North Carolina and Pittsfield Township, Michigan all provide reminders that no company is exempt from disaster. Some businesses may have greater susceptibility, but it’s everyone’s responsibility to do what it takes to prevent tragedy. Fire prevention often has many moving parts, so let’s focus on one seemingly small aspect relating to pallet rack today: the importance of pallet rack flue space.

How could something so small have such a huge impact? First, it is important to understand what flue space is and what it does. A flue space on a pallet rack does not prevent a fire from happening. When applied to pallets in racks, it will send heat and smoke upward and delay the spread of fire.

The National Fire Protection Association defines flue space as clear vertical lines of sight from the floor up to the ceiling within rack storage areas. There are two types of flue spaces – transverse flues and longitudinal flues. Transverse flue space is the space between rows parallel to the direction of loading. Longitudinal flue space is the space between rows of storage perpendicular to the direction of loading with a width not exceeding 24 inches between storage.

In the event of a fire, a flue space allows fires to vent upward instead of across multiple pallet racks. The theory is a fire venting upward contains the risk to a confined space, allowing sprinkler systems to extinguish the fire or keep it from spreading until firefighters arrive.

Guidelines for flue space

As mentioned, the NFPA sets guidelines for determining flue space for pallet racks. These guidelines are for minimum flue spaces. However, your local building codes may be slightly different so be sure to check. Pallet flue space is required for all racks having storage for single, double or multiple rows of pallets with a height of 25 feet or higher. The longitudinal flue space is not an NFPA requirement for racks less than 25 feet, but you should verify with your local fire department to double check local on any local variances.

NFPA’s minimum flue space requirements for longitudinal (vertical) flue are six inches from bottom to top. This is six inches of space between rows of pallet racks set back-to-back with no obstructions.

The same is true for horizontal or transverse flue space. This is space between each pallet on a rack (storage system). The transverse flue minimum requirement is three inches. Again, these spaces must have no obstructions.

Avoid temptation

The flipside of this discussion is productivity and profitability. Some businesspeople may feel the need to fudge on these requirements for the sake of gaining X more pallet space. This may be tempting but please, do not do this. Between fines, possible closure of your operation (until changes are made) or even a fire occurs, the risk far outweighs any potential reward.

Devices are available to help your team from encroaching upon flue space. Items including row spacers, straps, netting and even the addition of a beam all help prevent obstructions in flue space. Training is another method of ensuring no flue space violations. Help your operators understand the importance of keep this space open. Make sure drivers understand certain pallets will not fit in some racks. Make accommodations so your drivers know what to in those circumstances.

One fire is one too many, particularly when it is preventable.