More warehouses are flipping the switch and turning out the lights. They’re going dark. A “Dark” warehouse is a term used for a storage facility that does not require the use of lighting for normal operation. Depending on the type and size of goods handled these warehouses are often fully automated, using such technologies as autonomous guided material handling equipment, warehouse execution systems, and automatic identification.
Dark warehouses are increasingly being used by online retailers and supermarkets. Cold storage or freezer warehouses, such as those used in the food and beverage or pharmaceutical sectors, are particularly suitable to ‘go dark,’ requiring less people to work in adverse conditions like sub-zero temperatures. An Australia-based dairy exporter, for example, recently consolidated its distribution network and six warehouses under one dark warehouse facility. The first of its kind in Australia, it is highly automated, using impressive state-of-the-art systems, robots to pick and pack orders, and “dark” cold storage. It is also one of the very few facilities in the world that is both ambient and temperature-controlled under one roof in a highly automated environment.
Piled High
These advances in technology have made it possible for better utilization of the warehouse space by increasing vertically their storage capacity. It is not uncommon to encounter warehouses storing commodities over 40 feet and even 100 feet high. The technology, such as storage retrieval systems for transferring palletized cased goods to and from the racks, adjusts to these heights. Stacker cranes are designed to work in narrow aisles nearly 100 feet off the ground and are fitted with optical equipment for controlling the drive and lifting position, detecting crossbeams on racks to allow for precise stacking of the pallets on a specific position within the rack.
From a business point of view, the benefits of highly automated, dark warehouses are very significant. They provide nearly 100% error-free operation, obtain optimum storage with nearly perfect alignment of goods within the racks, present low rejection rates of goods due to proper handling, and offer the ability to track goods from point of origin to shipping and real-time inventory control.
High density warehousing, however, using very tall rack storage in the dark, can be risky posing significant potential for high-value property damage and business interruption.
Pushing Fire Protection Challenges to New Heights
The National Fire Protection Association (NFPA) has long recognized that warehouses present special challenges for fire protection because their contents and layouts are often conducive to fire spread and present obstacles to fire suppression efforts. Warehouses – dark or otherwise – vary in size, types of materials stored, design, storage configurations, construction, technologies, ceiling heights and other factors that present special challenges for fire protection. (For some helpful fire prevention tips, see .)
The increase in the number of very large and tall warehouses has an unintended consequence; the increase of the potential fuel loads can have a significant impact on both fire loss experience and fire protection systems. Dark warehouses present additional challenges resulting from minimal lighting, narrow aisles, overload of storage racks, and mechanical failures of equipment. Overload of storage racks and mechanical failure of equipment associated with automated warehouses present a potential for property damage. Although the risk of accidents and damage to racks is negligible, the rack system itself is usually integrated into the building during construction. Often, racks support the building roof, presenting a potential for roof collapse under severe fire conditions.
Storage heights exceeding 45 feet, which are the currently recognized maximum heights for ceiling sprinklers by the NFPA 13 and FM Data Sheet 8-9, present major fire protection challenges, requiring the installation of in-rack sprinklers for effective fire control. (Download Luis’ full white paper on Dark Warehouses for an outline of proposed fire protection using both conventional and non-conventional methods and applications.)
In dark warehouses, total reliance must be placed upon sprinkler protection for initial control.
Risk Mitigation
Adequately designed, automatic sprinkler systems are essential for proper fire protection. In dark warehouses, total reliance must be placed upon sprinkler protection for initial control. According to the National Fire Protection Association, wet pipe sprinklers have been proven effective in 84% of the fires in which they were present. They also contributed to a 61% reduction in dollar loss in those fires. The design and installation should be based on the requirements of the NFPA 13 Standard for the Installation of Automatic Sprinkler Systems. A sprinkler design scheme should be selected from this standard and/or from the FM Data Sheet 8-9: Storage of Class 1, 2, 3, 4, and Plastic Commodities.
For early fire detection and depending on the commodities stored and the operating environment, consider the installation of a very early detection system or a linear heat detection system installed at all levels of the storage racks. All fire detection and protection systems should be arranged to transmit a local audio-visual alarm, and to transmit the alarm to a constantly attended location and Alarm Monitoring Central Station.
Appropriate building codes should be used in the design of very tall, dark warehouses. This should include the latest codes for building construction and reference to applicable fire protection standards. One of the first steps in building design is to determine potential exposure to natural catastrophe events such as earthquake, wind, flood, snow and lightning among others. This is particularly important in dark warehouses as they are often built near ports and bodies of water.
Loss prevention and control management programs can also offer guidance for safe operation of dark warehouses:
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Adequate protective devices for material handling equipment for safe operation.
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Preventive maintenance program for the electrical equipment and storage racks.
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Comprehensive pre-emergency and response plans for all conceivable emergency situations.
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An inspection program for the fixed and portable fire protection program.
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A work permits system for performing inspection and maintenance work.
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Proper surveillance and security systems.
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Proper lighting in the warehouse to facilitate egress, firefighting, and inspections and maintenance
Conclusions
Dark warehouses pose major fire protection challenges due to the high-density storage arrangement. A fire in this type of warehouse without appropriate fire protection is likely to result in major property damage and cause massive interruption of the supply chain.
The lack of lighting and potential for building or rack collapse present a challenge to firefighting which necessitates conducting a risk assessment, starting at the conceptual design stage of the facility for identifying the potential risk exposures and the required preventive and protective features. The installation of automatic sprinklers is essential for control of a fire situation. Although, in most cases, sprinklers do not extinguish the fires, properly designed sprinkler protection will control the fire to provide a degree of safety for access to firefighters. Pre-emergency planning and business continuity planning area also essential for proper loss control.
To learn more, download Luis’ Dark Warehouses: Loss Prevention, Fire Protection Challenges and Risk Mitigation Measures white paper, or contact luis.arango@xlcatlin.com. Visit the website
