Private Hydrant Systems For Factories and Yards
Industrial Fire Safety
Industrial plants with unsprinklered buildings and yards with combustible storage need private hydrant systems that will supply the required water flow for fire protection. These hydrant systems can be used as an auxiliary water supply for buildings with sprinkler systems as well as for feeding hose lines for fighting fires in and about the plant.
Before installing a hydrant system, you should first give thought to providing sufficient water volume and pressure in the system. First, your insurance carrier or company fire protection engineer must establish the required fire flow and determine how to provide it. Otherwise, private hydrants may not supply enough water for fire fighting and the money spent on their installation then can be classified only as a useless investment.
Underground mains and the lateral connections to hydrants should never be smaller than 6 inches and larger if necessary to provide the desired fire flow.
Hydrant spacing: The distance between hydrants will vary according to the requirements of your insurance underwriter, who should be consulted before an installation is made. NFPA Standard No. 24, “Outside Protection,” states, “There shall be sufficient hydrants to concentrate the required fire flow about any important building with no hose line exceeding 500 feet in length.” Public hydrants are considered in applying this requirement. The Factory Mutual Engineering “Handbook of Industrial Loss Prevention” states that hydrants can be 100 to 300 feet apart, according to the hazard. So first investigate and then plan system installation to meet your particular need.
Hydrants should be at least 50 feet from buildings—or protected by fireresistive half-walls or other shielding— to protect hydrants, apparatus and personnel from heat and falling walls.
Depending on the available water and the hazards protected, hydrants should have three 2 1/2-inch gated outlets for individual hose control or two 2 1/2-inch gated outlets and one pumper suction connection. All yard hydrant threads should be the same as those on the local municipal hydrants. Regretfully, we do not see too many gated outlets in today’s industrial plants. The cost is small and the returns are great in gaining proper water control.
Water supply: When the same water supply is used to feed both sprinkler systems and yard hydrants, it is important to have a large enough flow for all fire uses. Both the plant brigade and the municipal fire department should be kept fully informed of the water supply limitations, and through periodic joint drills, they should be trained in the proper distribution of the available water flow. The proper use of water can’t be stressed strongly enough because the losses in many sprinklered buildings are greater than they should be as a result of improper use of pumpers at hydrants and hose lines.
If hydrants are likely to be damaged by trucks and other vehicles, they should be protected by stanchions made of steel beams or pieces of railroad track, which can be connected by lateral pieces of steel. Make certain to leave sufficient room for connecting a pumper suction and hose lines.
Hydrants should be inspected and tested by flushing at least annually. Any indicated repairs must be made promptly to maintain fire protection.
Hose houses: Depending on the anticipated use and the availability of a municipal fire department, hose houses with equipment must be provided as necessary. The types of acceptable hose houses or equipment cabinets include: (1) the five-sided wooden or metal hose house that encloses the hydrant and provides equipment storage, (2) the lower profile, four-sided, metal hydrant enclosure with twin front doors and a liftoff top for easy access to all gear, (3) an all-metal, oblong hydrant enclosure with a nonremovable top, (4) a free-standing equipment cabinet or house, on legs or mounted on a building wall adjacent to the hydrant, (5) homemade configurations of wood, steel, brick or concrete—or any combination of these materials—to meet the special needs of a plant.
The five-sided, wooden hose house creates painting, maintenance, alignment and rodent problems. As a result of experience, we feel that the metal, free-standing or wall-fastened, equipment cabinets are the most practical and useful storage facilities commercially available.
Equipment required: In many cases, the desires of the insurance carrier govern the hose and hydrant equipment that should be stored in a hose house. However, the NFPA recommends that a hose house contain two underwriter playpipes, one fire ax, one crowbar, two hydrant wrenches—one in storage and one on the hydrant, four coupling spanner wrenches, two hose straps and two 2 1/2-inch hose gaskets. It is suggested that the hose be 2 1/2-inch, either single or double jacket according to the use anticipated, with neoprene liner and couplings to meet local requirements. The number of hose lengths must be adequate for the distances to be covered and can be determined only after surveying the location protected.
Besides the recommended equipment, you might consider including 1 1/2-inch hose and gated 2 1/4 X 1 1/2 X 1 1/2-inch wyes for reducing 2 1/2-inch lines to 1 1/2-inch. Adjustable stream nozzles with shutoffs are essential for stream selection and line control. Besides practical fire fighting with this equipment, you also can expect a safe operation.
Another form of storage building used in the larger industrial operation is a hose cart or reel house. These enclosures are much larger than the usual hose house as they are used to store hose and allied equipment on a large wheeled hose cart. These carts, placed strategically around the premises, are pulled by brigade members to the emergency location.
Whatever form of yard fire protection you chose must be adequate for the hazards, designed for use in connection with local fire department equipment and maintained on a scheduled basis.