We received a comment on our first FM Approvals blog post and decided to dedicate another post to the answer. You can check out the original article and comment here. In a nutshell, the user commented that FM certification is only useful for brand new towers because scaling and buildup can be flammable.
Tower manufacturers run full-scale tests on new cooling towers to determine if the tower design is capable of preventing the fire from propagating to adjoining cells (for multi-cell FM designs). These tests provide owners with confidence that the tower design is able to limit the effects of a fire event. It is important to point out that we are speaking about a standard test that decides whether or not the cooling tower can be listed as FM approved for use without a sprinkler system. If this specific certification is not needed, then a sprinkler system can (and should) certainly be utilized as part of the tower’s risk management program.
A common misconception is that fouling will increase fire potential or negate the effectiveness of an FM tower design. In most cases, the accumulated materials are solids, minerals, muds and salts, and biologicals that are found within the circulating water. These are materials that may cause, or be the result, of what the industry terms “scaling” or “fouling” in a cooling tower. These materials would not typically be viewed as a source of increased fire potential. Usually the fill, piping, drift eliminators, or structure itself are the most flammable components of the cooling tower, and unless the buildup of material is of a flammable nature, then there should not be an increase of fuel to burn compared to when the tower was tested as new.
One instance where the materials might increase a tower’s fire potential would be in the case of a pulp or paper mill where there may be an accumulation of combustible fibers. If these organic fibers were to dry out and ignite from an outside source, then you could potentially see additional heat from this combustion as compared to an FM burn test of a new tower.
Every facility and process is unique, and not every application requires an FM approved cooling tower without the need for a sprinkler system. As a trusted manufacturer, it is our responsibility to try to educate and support owners the best way we know how based upon listening to their concerns and applying our knowledge. An FM approved tower is not necessarily beneficial to every operation, and for that reason, the FM certification requirement is not always needed. The determination is a risk assessment and loss prevention determination based on each owner’s unique requirements.