House Fire Prevention by Edward R. Nickerson The first automatic fire sprinklers were commercially marketed in the US in 1874. There have been minor advances in the basic technology since that time, despite the ever increasingly complex governing codes and standards that result from evolving occupancies, fires, new research and ever increasing public awareness. Properly designed automatic sprinkler systems control fire, reduce property damage, business interruption and save lives. However, this requires routine inspection, maintenance and testing as well as continual reassessment to assure success. Concerns relating to the major components are discussed below. Consult NFPA 25 “Inspection, Testing and Maintenance of Water- Based Fire Protection Systems” or other appropriate codes/standards for detailed requirements. Sprinkler Heads Automatic sprinklers discharge water through an orifice when the heat from a fire fuses a thermal element. Once fused, the water impacts a deflector and is dispersed in circular pattern. Automatic sprinkler systems are designed to operate many heads simultaneously. In order to control or suppress a fire the heads must operate without delay. Look for damaged deflectors, painted thermal elements, leakage, corrosion, physical obstruction, or older (obsolete) sprinklers. Test or replace heads if their reliability is questionable. Control Valves Sprinkler control valves are provided for the purpose of shutting off water to the sprinkler system in the event of accidental leak or for system maintenance. Valves that are inadvertently left closed can impair a sprinkler system. Inoperable valves can cause significant water damage if they cannot be quickly closed. Periodically inspect sprinkler control valves to insure that they are in the open position. Functionally test them to ensure that they will operate. Consider locking or sealing valves in the open position to deter against unauthorized tampering, particularly if they are accessible to the general public. Develop an impairment management program to ensure that any valve closures are monitored, that the number of impaired systems is minimized, that protection is restored promptly and that proper precautions are taken to prevent against fire when systems are impaired. Dry pipe, preaction and deluge valves are designed to introduce water into the piping network after being tripped. Dry pipe valves are designed to operate when an automatic sprinkler head fuses and the system’s air pressure drops. Deluge valves are used with open heads and operate when signaled by a detection system. Preaction valves, and related designs, employ both methods of activation. Periodically test all detection systems, and devices such as accelerators and exhausters that effect riser control valve actuation. Routinely trip test and maintain all dry pipe, deluge, and preaction valves to ensure their proper operation. Piping Obstructed piping results in an impaired sprinkler system. Obstructions occur in cast-iron pipe as a result of tuburculation. Dry systems have the worst track record with corrosion, and galvanized piping is commonly installed to compensate. Obstruction can occur when from foreign materials, or living organisms, are introduced via the water supply (e.g. rocks, sediment, clams, microbiological induced corrosion (MIC), etc.). Sudden failure can result in deteriorated pipe when systems are exposed to high flow and pressure during fire conditions. Galvanized pipe corrodes quickly at elevated temperature. Flow 2 in. drains and inspectors test connections to ensure that system piping remains unobstructed. Dry pipe systems that use cast-iron pipe should have flushing investigations performed routinely. Periodically inspect freezer systems for ice plugs. Treat and inspect systems that are prone to obstruction/deterioration from MIC, Asian clams or zebra mussels. Thoroughly investigate any obstructions promptly and determine the cause. This will likely require disassembly and/or flushing of all piping. Flush the system by flowing water through the largest pipes first so as to not introduce large amounts of obstructing material into the smaller pipes. Adequate velocity is essential. In winter it is critical to maintain adequate building heat to prevent freezing. Check dry systems for proper piping pitch and drain drum drips routinely. Inspect dry pipe valve riser houses to ensure adequate heating. For older and suspect systems that have leaked or failed, conduct a hydrostatic pressure test to determine suitability for continued use. If testing cannot be performed, replace the system. Water Supply The water supply consists of a source and a means of delivering adequate flow and pressure to the automatic sprinkler system. Sources include tanks, wells, lakes, ponds or rivers. Flow and pressure is supplied by gravity, pumps and in some cases pressure tanks. Large public water systems utilize a redundant combination of gravity and pumping and are generally reliable. However, uncontrollable changes may impact system adequacy. Sources, pumps, underground piping and valves are subject to impairments that could render an automatic sprinkler system ineffective. Perform flow testing in the vicinity of the automatic sprinkler system to assure that the design remains adequate. Inspect and maintain control valves as outlined above. Flow test isolated underground main legs to ensure that there are no obstructions. Test start fire pumps frequently to ensure that they will start automatically. Flow test fire pumps to assure their continued performance. In winter, routinely check heating systems in tanks and fire pump rooms to prevent against freezing. Treat raw water sources for clams, mussels and excess vegetation, and routinely clean suction intakes Reevaluation Continually reevaluate sprinkler system adequacy to ensure the systems remain capable of protecting property, reducing business interruption and saving lives. Reevaluate changes in occupancy, combustible load, storage configuration, products and processes. Apply the most modern codes and standards, and reassess the water supply for comparison to each sprinkler system’s calculated demand. Edward R. Nickerson, PE is the President of Reckon It, Inc., supplier of 185Graph, the only 1.85 graph based sprinkler calculation software for hydraulic analysis and elementary sprinkler design. 185Graph is relatively inexpensive and perfect for performing quick and accurate “what-if” calculations on most installed automatic sprinkler systems. Please visit our website at http://www.reckonit.com today.

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