1.1* Scope. This standard applies to fire protection for field erected and factory-assembled water-cooling towers of combustible construction or those in which the fill is of combustible material. A.1.1 This standard does not apply any more or less strictly to factory-assembled units than did earlier revisions. Because these units have typically been steel frame/structure with PVC fill, the protection requirements should be evaluated in accordance with Section 4.2, with item (2) being specifically noted. In all cases, Section 4.2 should be reviewed for making the determination with regard to the installation of fire suppression systems. In some cases, no fire suppression is required. The fire record of water-cooling towers indicates a failure to recognize the extent or seriousness of the potential fire hazard of these structures either while in operation or when temporarily shut down. Water-cooling towers of combustible construction, especially those of the induced-draft type, present a potential fire hazard even when in full operation because of the existence of relatively dry areas within the towers. A significant percentage of fires in water-cooling towers of combustible construction are caused by ignition from outside sources such as incinerators, smokestacks, or exposure fires. Fires in water-cooling towers can create an exposure hazard to adjacent buildings and processing units. Therefore, distance separation from buildings and sources of ignition or the use of noncombustible construction are primary considerations in preventing these fires. Ignition within these structures can be caused by welding or cutting operations, smoking, overheated bearings, electrical failures, and other heat- or spark-producing sources. Fires have also occurred during the construction of water cooling towers. Measures should be taken during construction to prevent the accumulation of combustible waste materials such as wood borings, shavings, scrap lumber, or other easily ignited materials. “No Smoking” regulations and strict control of welding and other heat- or spark-producing operations should be enforced. Wetting down combustible portions of the tower during idle periods of construction is a good fire prevention practice. Where cooling water is supplied to heat exchangers that are used for cooling flammable gases or liquids or combustible liquids, and where the cooling water pressure is less than that of the material being cooled, an unusual hazard to the cooling tower can be created by the return of the flammables or combustibles to the cooling tower water distribution system.