Keeping your warehouse safe means having adequate flue spaces to allow water from an overhead sprinkler system to reach the lower levels of your rack. Pallet rack systems that incorporate the appropriate flue space specifications are more effective at reducing fire risk than solid rack systems. When designing Pallet rack applications, there are two types of flue spaces that need to be considered:

Transverse flue space = the space to either side of a pallet in a storage system.  Typically, this space should measure a minimum of 3 inches.  In the picture below, the transverse flue space is measured at 5 and 6 inches.

Keeping Your Warehouse Safe with Adequate Flue Spaces

Longitudinal flue space = the space between rows of back-to-back racking.  Typically, the longitudinal flue space is a minimum of 6 inches between the loads.  This distance between the racks should be even greater because it will include the minimum of 6 inches between the loads as well as the load overhang which is typically 3 inches for each back-to-back bay as shown in the picture below.

If you have any questions regarding flue spaces, tell us about your next project we will be happy to help! 

Source: http://www.wikimheda.org/wiki/Transverse_flue_space, http://www.wikimheda.org/wiki/Longitudinal_flue_space