Fire Hazard in Brewers Grains
A number of fires in feed mills of New York State, one of which resulted in loss of life and injuries, brought an investigation by the Bureau of Fire, Division of Safety of the State. As a result of its findings, the Bureau issued a Memorandum on Oct. 9, from which is quoted the following:
The fires in question all originated in storage bins of a grade of feed known as “Brewers Grains.” These are the residue of the grain used in the brewing of beer.
The spent grains are sold in bulk at the brewery. In this form, the product contains grains varying from coarse to very fine. It is usually very wet, and is often at a temperature as high as 180 deg. Farmers who buy the grains use them almost immediately. Feed dealers store dry, and distribute the grains. The length of Storage depends on market conditions, distance and method of distribution.
Brewers grains are subject to spontaneous heating if they are not properly dried before storage or shipment. This drying must be completed, within 24 hours after removal from the brewery, to a moisture content of between seven and twelve per cent. Drying to less than seven per cent results in an oxidation of vegetable oils remaining in the grains, and spontaneous heating to the ignition temperatures will follow. Grain with a higher moisture content will heat due to fermentation. During heating, it is reported that combustible gases are given off, and a serious explosion hazard may exist if sufficient oxygen is introduced.
The following procedures are recommended in case of fire or extreme heating involving a bin of brewers’ or distillers’ grains.
Do not permit anyone to enter the bin. (1) Stretch and charge hose lines with fog nozzles to all sections of the building, especially to the top of the bin and to the floor of the building immediately below the bin. (2) Wet down all dust with a spray or fog stream. (3) Ventilate the building. (4) Remove all grains from bins that are heating. This grain may be removed by the existing hoppers, or a section of the bin floor may be removed. All grain must be removed from the bottom of the bin. A spray or fog stream should be directed across the opening so that all grain is removed through the spray or fog pattern. Fog should also be directed into the top of the bin while grain is being removed. The most dangerous time of the operation is as the bin is nearly emptied. If air should enter the bottom opening in sufficient amounts to cause a draft, or to agitate the grain, an explosion might occur. As a preventive measure, the nozzle at the top of the bin should be placed in solid stream position and used to flush the balance of the grain out of the bin. High nozzle pressures should not be used for this operation. (5) Finally, do not permit firemen to enter the bin until all grain has been removed.