Hay Fires

New Zealand Journal of Agriculture, Volume 97, Issue 6, 15 December 1958, Page 588

Hay Fires

By

G. R. MOSS,

Instructor in Agri-

culture, Department of Agriculture, Wanganui, and P. DUNNE, Fields Instructor, Department of Agriculture, Westport

EVERY year hay fires in stacks, sheds, and dumps are numerous and causes of many of these fires are unknown. Little damage may be done when the stack is in the open, but in some seasons replacement hay may be very expensive. Today most hay is baled and stacked in sheds, often in the same shed as the farm machinery, and a fire in these circumstances can cause a heavy loss, as the shed and equipment are often uninsured.

WHEN wet weather makes the harvesting of hay difficult it is sometimes harvested loose and stacked. Excessive moisture in hay is the main cause of burning; hay with less than 30 per cent of moisture will not catch fire.

A fire hazard is constituted more by small pockets of wet material than by an average moisture content which is greater than 30 per cent. Poor consolidation of a stack allows for more air, without which no material can burn, but it also permits heat to escape more readily. Probably the danger is greatest when air is trapped in a consolidated stack, such as when tangled bundles are not teased out when stacked.

A rise in temperature to 120 degrees F. is brought about by respiration in the green portions of hay. This is accentuated to ' about 158 degrees F. by bacterial fermentation, and the production of volatile combustible gases raises the temperature still further to about 500 degrees F. In localised pockets the formation of the gases causes charring and the caking of surrounding, hay. Eventually the pressure of accumulated gases forces a route through the hay, a contact with the open air is established, and the hay readily bursts into flames.

The main requirement is to stack hay only when it is in a fit condition. Should this be impracticable, some of the difficulty can be overcome when building by placing bundles of sticks at 8 ft. intervals across the stack and below the eave. The use of salt in building can be recommended if heating is probable. Salt should be sprinkled over each layer; about 20 to 25 lb. of salt should be used per ton of hay. Salt sprinkled through hay retards the activity of micro-organisms, thus reducing fermentation and heating. Salt also is beneficial to palatability, colour, and aroma.

Causes of Fire Stacking Damp Hay Stacking damp hay can cause spontaneous combustion. Once the hay is smouldering control is difficult, as, in most cases, a smouldering stack opened up to the air immediately catches fire. Cigarette Butts A cigarette butt thrown out of a moving truck carrying a load of hay can cause a serious fire. Matches and Lamps In the Wanganui district recently a truck and its load of hay were burnt when the hay was ignited by the warning lamps on the side of a bridge under repair. Smoking Boys slipping away to smoke near stacks have often been responsible for hay fires. Crackers Crackers have often been the cause of hay fires. Tractors or Trucks Backed up to a Stack Exhaust sparks from badly tuned engines, faulty wiring on petrol engines, or hot bearings have all been known to start fires;* Flying Sparks A badly sited hay shed or stack can be ignited in a dry season by sparks from a railway engine or from a grass fire caused by sparks. .With the changeover to diesel engines, there is less danger of this type of fire. Precautions Hay should be Dry Hay should be dry when harvested and stored in well ventilated conditions. Siting of Hay Sheds It is not advisable to build hay sheds close to other buildings. Hay Stored near Machinery When hay is to be stored in sheds near valuable equipment, extra care should be taken to ensure that the hay is in good condition. A fire extinguisher or hose should be placed handy. Vehicles near Stacks Tractors and trucks, if driven into hay sheds or near stacks, should be well maintained. The parking site should be inspected after the vehicle has moved away.