Sprinkler concept developed for IKEA's Vertical Automated Storage Systems
The concept of VASS units
A VASS unit is an enclosed system of vertically arranged trays, an extraction platform and a series of computerized controls that delivers items to an ergonomically positioned workstation. The unit automatically locates and retrieves stored items with the push of a button or scan of a bar code. The trays handled by the system can be equipped with partitions and dividers, totes and containers, cases and cartons, etc. The benefits of this storage concept include maximum use of available space, increase productivity and improved worker safety.
The storage inside a unit is very compact. Technology is used to scan every tray’s height and the trays are automatically stored in the optimal space in the unit. A built in weight scale automatically checks a tray’s weight to protect against overloading of shelves.
It should be emphasised that the probability for a fire inside a VASS unit is low. The primary sources for fire ignition are related to computer control and the electrical motors associated with the extraction platform. Unauthorised personnel do not have access to the unit. Despite the high level of intrinsic safety, a built in fire protection system is often required.
The VASS unit used by IKEA
The VASS units used by IKEA are designed to fit their specific needs regarding the dimensions of the trays and the overall capacity. The trays are constructed out of steel, with solid side plates. The individual trays measure 4 m ├ù 0,8 m (W ├ù D). The rim height is 250 mm and, in the tests, two dividers were installed such that three compartments were formed per tray. The unit used in the fire tests had at total of 45trays, 25trays on the back wall and 20trays on the front wall.
In practice, the most common commodities stored in VASS units at IKEA are products, e.g. kitchen articles, doors, drawers and textiles, or similar items. Products from unexpanded plastics are not as common and products from expanded plastics are prohibited.
The unit used for the tests measured approximately 8m in height, 4,4m in length and 3 m in depth. The unit was supplied by Kardex, Bellheimer Metallwerk GmbH and installed inside the fire test hall at SP by personnel from Kardex Scandinavia AB. The installation of the unit is shown in figure1.