Why do hay bales spontaneously combust

Keeping Hay Fires from Spontaneous Combustion. Johnson Every farmer has heard stories of someone affected by a hay fire. Check fresh hay daily. If there is a distinct musty smell or a slight caramel odor, there is the likelihood that the hay is heating — keep monitoring the temperature.

Prior to entering a barn place long planks on top of the hay. Since even dew and fog can increase the moisture content of hay, most recommendations for preventing hay fires relate to careful monitoring — particularly of the internal temperature of the bale or stack. External warning signs of a high internal temperate are often created by evaporation particularly when hay is stored indoors. More than just observing steam rising from a bale although if you do — take action immediately , condensation on the roof and eaves of the barn also indicate the presence of steam and heat and too much moisture.

Molds often start to grow in these conditions and produce a telltale acrid, tobacco type odor which is a clear warning sign, as well.

Even without these signs, experts recommend internal temperatures be taken regularly, and even without a proper thermometer, this is easier than it sounds. Simply insert an iron bar into the stack as deep as you safely can, getting it as close as possible to the middle.

Leave it for two hours. When you retrieve it, if you have difficulty holding it due to heat, the temperature is in excess of Fahrenheit and action must be taken.

If it is too hot to hold, the haystack has already reached F — nearing the temperature at which spontaneous combustion of the hay will occur. If uncertain whether heat has damaged hay too much for feeding have a sample tested.

For additional information or assistance, contact your county Extension office. References Bledsoe, B. Bruhn, H. Hoard's Dairyman, June 10, ; p Murphy, Dennis and Arble, William. Smith, Gary L. Publication date: October Timothy G. Organization s : University of Tennessee Extension. More Like This.

Table 2. Recheck in a few hours. Move the hay to provide air circulation and cooling. Monitor temperature often. Call the fire department.

Continue probing and monitoring the temperature. Inject water to cool hotspots before moving hay. Have a charged hose ready to control blazing when moving hay. The smell or sight of smoke means a fire is definitely present. In any of these cases, call the fire department immediately. The proper procedure for controlling a hay fire is as follows: Knock down any visible flames.

A straight tip nozzle will result in deeper penetration. Probe for hot spots and inject water through the probe to cool the material and raise it to a moisture content that will prevent burning. Measure temperature every four hours and inspect mow.

Wet hay down and remove from the barn. Flames will likely develop when heating hay comes in contact with the air. Temperature rise is rapid above this point. Hay will almost certainly ignite. Caution: Before entering the mow, place long planks on top of the hay. Do not attempt to walk on the hay mass itself.

Pockets may have already burned out under the hay surface. Always tie a rope around your waist and have a second person on the other end in a safe location to pull you out should the surface of the hay collapse into a fire pocket. Extreme caution should be taken when fighting a hay fire if hay has been treated with chemical preservatives.