We make recommendations of clearances to be used within a racking system in the interests of safety and efficiency. These recommendations offer the operator the best compromise between storage density and operational effectiveness. If you don’t give your forklift truck operators enough room you will cause yourself problems and compromise the safety of your warehouse.
When establishing the clearances within a racking system the first consideration is the type of pallet or stillage to be stored. In the main there are two types – two way and four-way entry and they will be either 1200 x 1000mm or 1200 x 800mm. How these pallets are placed within the rack will establish the first set of clearances ie. back to back clearances and the pallet overhang. The recommendations are detailed in table one (right).
The height and width of the load will establish the next set of clearances – the clearance between adjacent pallets or loads and the liftoff clearance; that is the distance between the top of the load and the underside of the beam above. These clearances vary with the height of the storage system. Basically the higher you go the bigger the clearance should be. See table two.
Having established the fit of the pallet or load within the rack then operating clearances must be applied to moving the load using handling equipment. The fork lift truck is the major influence on the aisle width and transfer aisle dimension. For the purposes of this question we will divide fork lift trucks into two categories: Those requiring 90 degrees turns in the aisle to load such as counter balance and reach trucks, and those that remain parallel to the aisle and have forks operating at 90 degrees to the direction of travel.
For free roaming trucks – those in our category one – there are no clearances we can recommend. Your truck supplier will be able to tell you the trucks minimum operating aisle width with a pallet positioned across and along the forks. These dimensions will be based on the trucks dimensions and turning radius.
We recommend that within narrow aisle schemes – those with trucks that do not turn in the aisle – the clearance between the widest part of the laden truck and the face of the racked load is 100mm for mechanically guided trucks. If you are using wire guided trucks, this dimension should be increased to 150mm. These clearances may have to be increased if your floor is not to standard or you are going more than 12 metres high.
These recommendations are based on the SEMA Code of Practice for the Design of Static racking. Call SEMA on 021 200 2100.
More information is available from us in our booklet Safety in Numbers. Call our sales office for your free copy. Alternatively our website has more information on this and other elements of the design of racking systems in the Rack It library section of the site.