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2. Interrelation between environmental conditions for document storage and fire safety
2.1 Norms for environmental storage conditions for documents produced on different media
The physical environment in records and book storerooms must be evaluated by a variety of factors, the most important of which are the characteristics of the microclimate, i.e., the air temperature (t degrees Celsius) in the room and the relative air humidity (H. per cent). Considered together with the dustiness of the room air, these factors have a significant impact on fire safety in each storeroom, as well as in the library or archives building as a whole.
The standards for temperature, humidity, and other physical environmental conditions in the storeroom should be established by determining the optimum long-range storage conditions for the records being stored there. The requirements will vary according to the media upon which the information is recorded.
An optimum storage regime is assigned to each kind of information medium, based on its physical and chemical properties. Consequently, the norms for physical environmental conditions in storerooms are very similar in one country or another.
Commonly accepted norms for storage of information recorded on different media are displayed in Table 3.
Table 3. Basic norms for storage conditions for documents produced on different media
|Storage media||Conditioned Environment temperature/Celsius||% relative humidity|
|1. Paper base1||20 ± 1||45 ± 5|
|2. Magnetic tape||18 ± 1||40 ± 5|
|3. Glass plate photos||15 ± 1||35 ± 5|
|4. Black & white film1 2||15 ± 1||30 + 5³|
|5. Colour film1 2||-1 ± 1||30 ± 5³|
(1) Phonograph prints are classified as: paper base. Cine film and microfilm are classified under black and white or colour film.
(2) Storage requirements for cellulose nitrate and acetate film are the same. However, nitrate film should be copied as quickly as possible and disposed of. It should not be stored in an archives or library.
(3) Some conservators believe that the relative humidity should be set al 35 ± 5
2.2 The significance of climatic characteristics on fire safety
The climatic characteristics of a region have primary effect on the preservation of records in archives and libraries. There is a relationship between a region's climate and some specific fire hazards for archives or libraries.
The ignition and spread of fire through a building can occur anywhere, but hot climates can contribute to these fire hazards. Since chemical processes run at faster rates in hotter environments, these climates present a bigger danger for those archives and libraries which still have cellulose nitrate film in their collections, particularly if they are kept in non-conditioned storage areas. The same film in non-conditioned storage conditions in a more moderate climate could remain stable for a longer period of time.
Hot climates tend to have larger and more diverse populations of rodents and insects which can infest libraries and archives. Rodents can be particularly destructive to electrical wiring, damaging the insulation thus causing an electrical fire hazard. Termites or other insects which undermine the structural elements of a building may so weaken the interior supports that if a fire were to start it could spread quickly causing parts of the building to collapse thereby allowing the fire to spread throughout the structure.
2.3 Ways of maintaining the environment (climatic) conditions in library and archives buildings. Evaluating their effect on fire safety.
The heating and ventilation systems used in library and archives buildings provide storage conditions which can be categorized in one of the following three groups:
(a) completely conditioned storage environment; this can be provided by air-conditioning systems and air filtration (cleaning) systems;
(b) partially conditioned storage environment; this can be provided by warm-air heating, so that the storage environment conditions can be adjusted only by heating the air supplied to the storerooms. The air can also be cleaned by means of special filters. Both the completely conditioned and partially conditioned environmental systems can operate using greater or smaller amounts of outside air, thus limiting the volume of air that must be filtered to remove dust and harmful gases.
(c) non-conditioned storage environment; this is the case when central heating is used in the building and exhaust ventilation is used in the storerooms.
The level of environmental conditions established for libraries and archives may depend on the importance of the collections, the quantity, and the climatic conditions of the area. The former Soviet Union established norms for the construction of libraries and archives using an evaluation of the significance of the materials to be stored in a specific library or archive to determine the level of storage to be provided. The location of a new building in a moderate or hot climate will also be a factor in the decision process.
Fire safety in buildings has much to do with the choice of systems used to condition storage areas and their ability to maintain proper storage conditions in those buildings. Failure to provide proper storage conditions is potentially more dangerous in terms of fire hazards in hot climates than in cold or moderate climates. Therefore, when evaluating the extent of fire hazard in libraries and archives as they are influenced by climate, one must consider the effect of the external environment and whether or not the internal storage environment has been conditioned to mitigate the potential effect of the external environment on the holdings of archives and libraries.
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