Some Plant Fire Causes And How to Prevent Them
Industrial Fire Safety
Fire loss figures continue to grow with no decline in sight. Fire causes can be placed in many categories, as outlined in this column in November 1970. Some fire causes are simple, some complicated, as we will set forth in the hope that you will spot these causes and remove them.
One source of ignition to reckon with is friction. Friction can be created by two moving parts, or one moving and one stationary, such as a conveyer system. When friction occurs, the heat and sparks generated can ignite oils, greases or ordinary combustibles in the immediate area. Here, as in most fire causes, the real cause is man because the machinery was not adequately maintained and combustibles were allowed to accumulate. For loss records, however, the occurrence is listed under friction. The loss could have been prevented if the machinery was checked frequently, repaired and maintained as required. Also, good housekeeping would have removed the fuel.
Other fires caused by sparks or friction include the use of improper work tools in dust and flammable vapor atmospheres.
In the paper industry we must provide magnetic separators over incoming wood chips and supply conveyers as it is normal for logs, which are turned into chips, to contain an amazing amount of iron and other metals which must be removed to prevent fires from sparks in conveyers and during the manufacturing process.
Smoking problem: Smoking in plants is a definite fire cause. Recommendation number one is to prohibit all smoking, but it is almost impossible to do this except in very hazardous industries or process areas. Recommendation number two is to establish safe smoking areas with metal enclosures to the floor level. There should be butt buckets of metal, half-filled with sand or water, and good housekeeping. Smoking rules should be strictly enforced throughout the plant.
Some obvious fire causes gain little importance in the overall fire picture. They are known as hot surfaces, such as electric light bulbs, steam pipes, metal heater stacks, ducts and process ovens and dryers. Heat is transferred to combustibles by convection—with air as the circulating medium, conduction-direct contact with a hot surface, and radiation—produced by heat energy waves traveling through space.
Some fires are caused by metal stacks or ducts passing through combustible walls, floors and roofs with improper clearance. Dusts or oily residue on steam pipes, if proper conditions are present, smolder and eventually burst into flames, causing fires over wide areas—sometimes high above plant floors. To remove this fire cause, good housekeeping is a must. Bare light bulbs account for fires if they are in direct contact or close enough to paper, rags, combustible containers or flammable liquids. This fire cause could be removed by using bulb guards and fluorescent lamps and removing fuel close to lights. Process ovens or dryers installed directly on wood floors cause fires that can be prevented by installing them on concrete or masonry pads with air space between the pad and wood floor.
Faulty wiring: Probably improper wiring is the largest cause of electrical fires, which can originate in installations made by improperly trained plant electricians, inadequate wiring for the demand and lack of maintenance.
Electrical fires many times involve users of equipment at the failure spot, so we not only have a property loss situation but also possible injury or death. It should be noted that under the new federal fire regulations included in OSHA, the National Electrical Code must be followed in all installations, or plants will be subject to citations and/or fines.
Installations of new systems or changes in existing ones must be done by licensed electricians, well versed in industrial wiring and usage demands. Motor fires are common in industry because of the lack of maintenance. Also, low voltage can burn out a motor of considerable value faster than long usage or constant stop-start and overload situations. Therefore all wiring must be done in compliance with the code.
It is important to provide necessary grounds for electrical equipment and to replace frayed cables, wires, worn insulation, loose fittings, missing switch box covers and the like. All switch gear must be kept in closed boxes to prevent possible sparking and short circuiting, due to dirt or dust, that can cause fire.
Fuses or circuit breakers must be of adequate capacity to handle their loads. If frequent overloads and popouts occur, then corrections must be made to prevent such occurrences. We hope that no one bypasses fuses or circuit breakers, as this is a definite invitation for a fire.