GETTING THE MOST FROM YOUR PUMPING APPARATUS
BY GENE P. CARLSON
Are you prepared for the following scenario? The local newspaper prints a photo of your new 2,000-gpm pumper working at a fire with a single booster line operating. The article includes the fact that this $250,000 vehicle is discharging 50 gpm. The Fire Board chairperson calls and asks why you spent so much money to do so little. In addition, the manager or mayor calls with threats of budget cuts next year if the department cannot operate more cost effectively.
The history of pumping apparatus in North America began in the 1600s when fire apparatus was brought to the New World from Europe. Pumping apparatus was needed to combat fires in wood-frame structures. As cities developed and more and larger buildings were constructed, the bucket brigade and crude pumpers no longer were sufficient. Small fires rapidly spread from one wooden structure to the adjacent exposure. Cisterns were built to retain rainwater for fighting fires; small wooden water mains followed. Pumping apparatus and water systems continued to improve. Most large cities and many small towns, however, experienced conflagrations and block fires into the early 1900s.
Insurance companies quickly saw the economic problems associated with these large fires and soon developed a fire defense evaluation system, a grading system that rated the level of fire protection.
Over the years, however, many fire chiefs subscribed to the concept that “bigger is better”–a notion enhanced by the fire service`s strong pride and fierce competition, manifested in the desire to outperform the neighboring fire company or department.
The 1991 edition of NFPA 1901, Pumping Fire Apparatus, specifies a minimum pump size of 750 gpm. Most fire departments purchase a pump between 1,000 and 2,000 gpm. The most common pump size purchased today is 1,250 gpm. It is also the most practical. For industrial complexes and unique situations, larger-capacity pumps are available up to one capable of delivering 6,000 gpm from draft and more than 10,000 gpm from a water system.
Improvement in the engines that power the pumps has been a major factor in the development of larger pumping apparatus. Larger engines with ever-increasing torque and horsepower, up to 550 hp, have made it possible for large-capacity pumps to be made mobile. Also available is a 10-inch (250-mm) hose to deliver the flows of these large pumps.
The pertinent question now is, How large an apparatus do we need? The immediate answer in many cases is “bigger than Billville`s.” More specifically, we must ask the following questions: What are the functions of the unit? What equipment must be carried to perform these functions? What size pump is needed to deliver the needed water?
Fire protection in North America has always been considered a local responsibility. Thus, the community`s fire suppression needs should be given first priority. This need, of course, must be tied to the ability and desire to provide defined levels of fire protection. Small cities can rarely afford the resources needed to protect one major industrial plant where the probability of a disastrous incident is low–that once-in-a-lifetime fire. Automatic or mutual aid will be called for such major incidents. Large cities, on the other hand, cannot overlook the need to provide for rapid delivery of a large quantity of water at significant target hazards. Consider also that fire units sit idly at many working fires while firefighters are busily engaged–the apparatus served merely as a taxi. Could some other unit be used to transport personnel?
Surprisingly, the lack of a water system–or even the presence of an inadequate one–does not indicate the need for a smaller-capacity pump. Usually, where water must be taken from a static source, pumped from larger mains or other sources for long distances through large-diameter hose, or hauled in mobile water supply apparatus, pumps are necessary for maintaining adequate flows to the fireground. Large-capacity water systems with fair hydrant spacing (1,000 feet or less between hydrants) do not necessarily indicate smaller pump size. Although large pumpers may be needed for industrial complexes, such as petrochemical plants, pumps that deliver adequate flows at higher pressures are necessary for high-rise structures and for supplying master streams for frame or noncombustible buildings with large open areas or high fire loadings, providing elevated master streams, and providing a stream sufficient for reaching large or inaccessible exposures that must be protected.
Most pump manufacturers have designed excess capacity into their pumps. Remember, the pump is rated at draft with a 10-foot lift that requires considerable work by the engine. The issue becomes a horsepower problem, not a pump capacity problem. A 1,250-gpm pump will deliver 625 gpm from draft at 250 pounds per square inch. If the unit is working from a hydrant or being supplied by another pumper, much less work is required; and the pump will exceed its ratings at all pressures. Adequate flows at sufficient pressures can be obtained with a 1,250-gpm pump 95 percent of the time.
Besides pump requirements, another major consideration when specifying a new pumper is versatility. Options include the location of the pump (midship, rear, front, intracab, under cab); the location of the controls (with the newer technology, pump controls can be placed anywhere on the apparatus); the size, placement, and piping of pump inlets to obtain capacity; the number and size of outlets (no outlet more than 212 inches can be placed at the pump operator`s panel); the number and size of preconnected hoselines for a speedy initial attack; and the manner in which the hosebed is divided for straight, reverse, split, or multiple lays or some combination of these features. If only two preconnects are planned, put one on the front bumper and one in the rear hosebed. In this way, they will not interfere with the pump operator. The rear one should be piped only to the front of the hosebed at the top of the pump. This eliminates elbows and piping and reduces cost.
Although easy to pipe, a conventional midship-placed pump needs considerable space that can be put to better use. Further, unless the pump panel is top-mounted, the operator can be exposed in heavy traffic areas. Moving the pump forward or to the rear often improves weight distribution, since the tank can be moved forward. Also, additional compartment space is gained, and the operator is placed in a safer position. Rear-mounted pumps provide easier access for making and breaking hose connections. Top-mounted pump panels improve visibility and, when enclosed, provide protection against the weather. Some feel that enclosed pump panels cause the operator to lose “touch” with the fireground.
WATER TANK SIZE
Carefully review the size of the water tank and the plumbing to the pump. The current standard stipulates a flow of 500 gpm. This flow is sufficient for a small master stream, two heavy attack lines, or three 134-inch lines. Analyze your combination of attack lines to determine if the standard flow and tank size are sufficient.
Before writing specifications, the fire department must study the community needs in relation to size and response distances and times, climatic conditions, physical makeup and terrain, types of building construction, occupancies and fire loadings, water supply, and fire flow requirements. These needs should be combined with information on the area`s fire history, the current types of responses, and the planned and future growth potential of the community. If all the land area has been developed, the department should seek innovative changes that will enable the new apparatus to do a better job. In such an area, new buildings may have built-in fire protection, which may allow for smaller apparatus pumps.
The fire history allows you to identify factors that may influence future purchases. Among these factors are the following: the number of times various quantities of water were pumped, the times when pump capacity was insufficient, the times special pumping operations were used or needed, the costs for maintaining apparatus, the number of rescue or medical calls (if high, compartmentalization and equipment requirements may be changed), and the projections for the community`s future growth (the construction of single-family dwellings vs. warehousing, for example, will make a considerable difference in your department`s needs). After this analysis has been completed, fire department officials will be better able to determine which size pump is needed.
Among the innovative concepts that address the questions of how to provide fire protection for a community in the most efficient manner are the following:
The mini/maxi concept involves the use of fast initial attack units supported by larger, conventional pumpers. The mini responds to small fires and medical emergencies as a single unit. On regular structural alarms, the mini is supported by a large pumper and ladder company.
The midi/quint concept, in which a 750-gpm pumper and two firefighters plus a quint and four firefighters respond together. They may be assisted by a regular engine company or another midi/quint team. The midi responds alone with three personnel for medical calls.
The modified quint (less than a full ground ladder complement) concept has each unit equipped with an elevated master stream or a shorter aerial ladder and additional equipment. The first unit on the scene acts as an engine company, the second as a ladder company, and the third as the second engine for water supply. The firefighters of each unit perform the duties of the arriving position (engine or ladder); they do not attempt to perform both functions.
Some departments` approach has been to equip ladder and rescue companies with a booster pump and small tank so that, when necessary, the first unit on the scene can initiate a fire attack.
Another concept being tried is the blending of ambulance, rescue, and initial knockdown into a single unit, achieved by placing limited rescue equipment and a pump on an ambulance or building pumpers with transport capability in medical emergencies.
A relatively new concept gaining acceptance is that of adding Class A foam (a water-additive surfactant that enhances extinguishment) capability to any initial structural attack vehicle.
Another relatively new concept also gaining acceptance is the rescue-pumper with structural firefighting capability that incorporates additional compartment space for rescue equipment, air compressors, electrical generation devices, and floodlighting.
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How large a pump does your department need? A 1,250-gpm pump probably would do all you need it to do. The answer to this question, however, should be determined only after your department has considered the points discussed above and those local conditions that have not been identified in this short article. Remember that few departments have the firefighters, hose, and nozzles to deliver the full capacity of most large pumpers. As an example, a 1,500-gpm unit could supply six 212-inch lines that require at least three firefighters each.
Determine the fire flow needs in your response area, review the water supplies available, and determine the pumping operations needed to move the water from the sources to the target hazards. Then, the delivery capabilities–volume at necessary pressures–will determine the proper pump size to meet your department`s needs.
By reorganizing your thinking at the time you`re preparing specifications for new apparatus, your vehicle`s layout can be organized so that functions can be added without having to increase the size of the apparatus. Your objective should be to achieve increased utilization and functionality–not to prove that bigger is better. n
GENE P. CARLSON, a fire education and training specialist, is director of international marketing of Oklahoma State University`s Fire Protection Publications, representing IFSTA nationally and internationally. Carlson is a member of various committees of the National Fire Protection Association and the International Association of Fire Chiefs. He served on the staff of the National Fire Academy, the University of Maryland Fire and Rescue Institute, and the University of Illinois Firemanship Training Program.