Purple-K Protects Brooklyn Oil-Gas Plant
WHAT SOME ENGINEERS regard as the last word in industrial fire protection is now guarding the Brooklyn Union Gas Company’s Greenpoint works in Brooklyn, N. Y., one of the nation’s largest oil-gas manufacturing plants.
Designed to suppress quickly any fire in a generator house criss-crossed with high-pressure oil lines, the new fire system consists of: a spherical tank containing 4,000 pounds of Purple-K, the highly effective potassium bicarbonate dry chemical fire-extinguishing agent; a series of 11 hose stations supplied with dry chemical, which is directed from the supply tank through selector valves which, in turn, direct the chemical to the hose stations on two upper floors where a fire might occur. Eight 400-cubic-foot cylinders of nitrogen, each with 2,640-psi pressure, are used to expel the extinguishing agent.
Potassium bicarbonate-base dry chemical, developed by the Navy for aircraft crash fires, has only recently become available to industry. It is rated by Underwriters’ Laboratories to be approximately twice as effective as sodium bicarbonate-base dry chemical.
A unique feature of the system at Greenpoint is that it may be activated by pulling a lever at any one of the remote stations without one having to go back to the tank area itself on the ground floor. Also, the remote hose lines may be operated singly, or in various combinations.
Emergency push buttons that immediately halt the pumping of oil in all fuel lines throughout the building are located near each remote station and at other locations in the building. In addition, a supplementary fire system, consisting of salt-water hose lines with fog nozzles, is available to cool down metal after extinguishment by the dry chemical, thus preventing possible re-ignition.
Quite compact in appearance, the heart of the new dry chemical system occupies a space only 17 feet in length, 10 feet wide and 6 feet high on the ground floor of the generator house.
Describing the Brooklyn Union system as unique in both concept and performance, engineers in the Fire Protection Products Division of The Ansul Company which designed the unit, said they believed that the 4,000pound capacity of the system gives that utility one of the greatest concentrations of fire-killing power ever to protect a single fire hazard in the industry.
Nature of the exposure
The generator house, in which the new fire system is located, was formerly used by Brooklyn Union Gas Company for the manufacture of carbureted water gas of approximately 537 Btu’s per cubic foot. When the company converted a few years ago to the sale of natural gas with 1,000 Btu’s per cubic foot, the generator house became a supplementary or stand-by plant, which went into action only during periods of extended cold weather, or when pipeline transmission of natural gas from Texas was restricted for one reason or another. In order to adapt the old generator house to the manufacture of 1,000Btu oil-gas, it became necessary, among other projects, to increase the plant’s fuel consumption drastically.
With a capacity of 102 million cubic feet of manufactured oil-gas per day, the Greenpoint works is one of the largest plants of its kind in the United States. When under full operation, its 11 oil-gas machines in the generator house consume 60,000 gallons of fuel feedstock per hour. To feed this amount of fuel into the machines, six pumps with a pumping capacity of 2,500 gpm at 250 psi are used. The fuel lines are of 6-inch diameter, with 2-inch-diameter branches running off to the generators and carburetors.
Features of the new system
The increase in oil-handling capacity prompted the company to decide on an improved fire protection system. After extensive consultations with engineers, a system was developed which permits an employee to start pouring the dry chemical onto a fire anywhere in the plant within a matter of seconds.
The 11 remote stations are all located near stairwells, so that in case fire breaks out on one floor, industrial fire fighters on other floors can quickly run hose up or down stairs and bring additional lines to bear.
At eight of the remote stations, the operators have 50 feet of 1-inch hose to work with, while the three other stations are each equipped with 100 feet of 1-inch hose.
The discharge range of the dry chemical from each nozzle is 40 to 45 feet. When operated singly, each has a flow rate of 11 pounds of dry chemical per second. This amounts to a total discharge time of 6 minutes before the extinguishing agent is exhausted if one nozzle is used. When four hose lines are operating in unison, the How rate for each line is 9 pounds of dry chemical per second, in which case the total discharge time becomes approximately 1 minute 50 seconds.
Instead of a maximum of 350 pounds of dry chemical available in a single wheeled unit, one operator now has up to 4,000 pounds of dry chemical to extinguish a fire.
The new system, with outlets strategically located, eliminates the time required to move wheeled or portable extinguishers to the scene of the fire. In fighting oil fires under pressure, the saving of these vital first few seconds often may be decisive in achieving extinguishment.