Risk of Spontaneous Combustion of Wet Hay
Information sourced from an article published by Steve Fransen and Ned Zaugg, Washington State University The recent flooding in Boulder County requires close monitoring of stored hay for signs of spontaneous combustion. Dry hay (stored at 15 percent moisture or less) is safe for long-term storage. However, if the hay has become wet the quality has been permanently changed and there is an increased potential of a fire hazard from spontaneous combustion. As microbial organisms grow in wet hay they produce heat while drying out the surrounding surfaces of the hay for energy. More drying surfaces produces more microbial growth and different types of microbes live and die as the internal bale temperature climbs. When the bale temperature reaches about 150 Fº the hay is on a one-way street and going the wrong direction! The larger the haystack and the more densely packed the hay is the longer it may take to show signs of internal bale burning. Internal bale temperature may take several weeks before reaching 150 Fº, but from this point on more heat resistant bacteria start a process of chemical change that rapidly increases temperatures to the point of spontaneous combustion.Chemical reactions and microbial growth in hay occur because of the change in availability of moisture, oxygen, and pressure to create heat to the point of ignition and fire. Early warning signs are: Steam rising from bale surfaces and condensing on the roof and eves of the barn. Often molds will start to grow on all these surfaces too. An acrid, hot, tobacco […]
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