If warehouses put money to sleep then cold stores are the worst offenders because not only are the initial building costs much higher than for ambient warehouses so, too, are the running costs, where energy alone can absorb up to 25% of total running costs. Even the dynamic part of the cold stores equipment, like specially treated forklifts, costs much more because these should either be fitted with temperature-controlled cabs or, if health guidelines are followed, the recommended break for personnel should be 15 minutes in every hour outside the store.
When establishing a new cold store warehouse whether automated or not it is critically important to get the design right first time. The exercise requires an enormous level of planning, and given the amount of cost in such a project one easy way out would be to use a third party logistics provider with wide cold store operational experience. They will have cut their teeth on the issue and so should be fully aware of all the pitfalls. It would also make sense to visit some cold store sites to see if anything can be learned by their experiences.
Given the necessity to maximise the use of the cold store cube, harmonized with the right level of storage accessibility, the choice of racking plays a key role. Heavily favoured is the mobile racking, which gives the densest storage advantage of all racking types consonant with FIFO, but about three times as costly as APR racking. Drive-in/drive through is sometimes used and offers high density levels but there is no instant, 100% accessibility and it is notorious for accidents. This leaves APR as the third main choice but it is the least space efficient. However, this problem can be partly addressed by using the most space-efficient forklift which means forget about conventional counterbalanced trucks where restricted lift heights are also a disadvantage. Reach trucks are commonly used in cold stores but they need at least 2.6 mt wide aisles. A better choice could be articulated forklifts, which need only 1.6-1.8 mt wide aisles. Both these and reach trucks can lift to 12 mt, against only 6-7 mt for counterbalance forklifts.
Cold stores carry extra risks to stored goods when compared with ambient stores, and part of that is poor management. It is vitally important to ensure no wide temperature and humidity fluctuations and that there is good air circulation. It has been known for temperatures to rise so much as to lead to stock losses running into millions of pounds. But the fire issue can also be just as potentially catastrophic. Even a small fire can cause a large financial loss owing to smoke contamination. The dry air inside cold stores increases the risk of fire and the low air humidity levels facilitates the outbreak of fires. The wooden pallets and packaging materials are highly inflammable in the dry air.
Increased automation carries additional fire risks. Cable breaks, overheating conveyor motors on pickers and belts and technical defects on refrigeration units are all risks.
Conventional fire-fighting systems like sprinklers reach their limits because extinguishing water must be mixed with anti-freeze. Freezing temperatures make the use of wet pipe sprinkler systems impractical so double inter-lock pre-action systems are often used but reliability concerns remain owing to formation of ice plugs in the piping.
Wagners’ OxyReduct active fire prevention system, on the other hand, offers cold stores reliable, preventative protection by feeding nitrogen into the protected area to minimise fire risk by creating a protective oxygen-reduced atmosphere, one in which the residual oxygen levels are kept below the ignition levels of protected goods.
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