Since pallet rack weight capacities vary with the types and sizes of uprights and load beams, the configuration of these components, the type of rack and other factors, it is necessary to contact the manufacturer of the particular pallet rack to find its weight capacity. Pallet racks may also have a weight limit plate posted somewhere visible, but this is not always the case.
Pallet rack manufacturers must provide buyers with the load capacity for each pallet rack type and configuration for pallet rack construction. Rack manufacturers use formulas for calculating the maximum loads for their pallet racks and strict standards for construction, which take into account every possible variant, including wind, earthquake, unbalanced loads and building attachment. In addition, manufacturers must include drawings of load applications, rack configurations and drawings of multiple configurations, if the racks have that option.
The owner of the rack is responsible for obtaining and attaching, in a visible area, the pallet rack's weight limit plates. These plates indicate load size, weight limits and configuration information for the rack.
The weight capacity for a pallet rack varies according to its configuration and components. Different sizes and types of vertical uprights and horizontal load beams have different load capacities. Combine this with the variety of available of configurations, and this makes for a large range of weight capacities. For instance, a pallet rack configured with more horizontal space between the uprights and more vertical space between the beams will hold less weight than one with less space between the uprights and beams. To ensure safety, follow the manufacturer's maximum weight limits for the configuration and components used for the pallet rack.
The maximum weight listed by a manufacturer for each pallet rack configuration and size is typically the capacity for the entire bay. This is crucial to understand in order to avoid overloading the pallet rack. The bay capacity refers to the total weight that will be tolerated in between the two uprights -- not the weight allowed per beam, per upright or per level. The bay capacity also includes the weight of the rack components. So in order to calculate how much weight each horizontal level will safely hold, first deduct the weight of the rack components and any accessories, then divide the remaining weight by the number of levels on the rack.
The weight capacity of the pallet rack will also vary depending on the type of rack. There are several different types: selective, pushback, gravity flow, seismic and drive-in, to name a few. The weight rating of a selective rack will be different from that of a gravity flow rack (a rack where pallets sit on inclined rollers so that inventory can advance to a pickup point). Consult the manufacturer with the type, configuration and component sizes to find the weight capacity of the particular pallet rack.
Weight capacities listed by manufacturers are based on evenly distributed loads and interior conditions. Loads that are not evenly distributed create the effect of being heavier. In addition, locations susceptible to seismic activity will have different weight capacities. Sometimes local building codes place more restrictions on pallet rack weight loads. All of these factors should be considered before purchasing and building the pallet racks.