BY DAVID R. BLOSSOM, ALCM, CFPS, CFI1
The adage “Necessity is the mother of invention” definitely can be applied to the fire pump. It is often taken for granted and is always out of sight, yet it is a critical part of the fixed fire protection for many buildings. A previous article established the fire hydrant as a critical link in the chain of fire protection; the fixed fire or booster pump is another critical component of the water supply system. Once usually found only in large manufacturing complexes or used for high-rise buildings, these types of pumps are now widely used for many applications. They serve only one purpose: to increase water supply pressure within a fixed fire protection system. They cannot create water-they can only boost the pressure of the fire protection water supply to provide sufficient fire flow for fixed fire sprinkler systems and standpipe/hose supply.
Because these pumps are often hidden in a service area or out-of-the-way places, they are often overlooked. However, you must recognize the importance of these fire protection workhorses in fire suppression operations and know how to operate them. Let’s take a closer look at these important devices.
HISTORY
When you look at the origin of the fire pump, it is easy to understand why it has been an important part of the fire protection water supply for so many years. Although it is difficult to determine exactly when the first fire pumps were put into service, it is well documented that they were used widely by the early 1900s. Early sales literature seems to correlate the explosive growth in the demand for fire pumps with the emergence of the high-rise building boom. This is logical, since the water supply systems for most major cities had been planned to meet water requirements for residential and low-rise occupancies. Thus, there was no demand for high-pressure systems capable of providing water supply at sufficient pressure to reach upper floors of tall buildings. As long as there was sufficient water supply in terms of gallons available, the simple solution was to provide a pump to boost the pressure to obtain the water supply needed for firefighting. Domestic water demands on upper floors could be satisfied using high-pressure, low-volume pumps or low-volume, high-pressure pumps to fill tanks on the upper floors, allowing gravity to supply pressure to the floors below the tank.
However, the demand for the sufficient volume and pressure needed for firefighting had to be achieved by supplying sufficient pressure and volume directly to upper floors. The solution was to install dedicated booster pumps with sufficient capacity and pressure to meet demands for fire sprinklers, standpipes, and combined sprinkler and standpipe systems. Before too long, the benefits of using fire pumps to improve fire protection water supplies led to their expanded use beyond high-rise applications and in large industrial complexes, hospitals, warehouses, and large facilities requiring augmented water supplies.
BASIC FIRE PUMP INSTALLATIONS
Essentially, fire pump installation has two basic parts: the pump and the driver. The pump serves the single purpose of providing the necessary flow and pressure to meet the demands and design of the fire protection system. Two basic types of pumps typically are found in most applications-the centrifugal split case and the vertical turbine. The centrifugal split case is usually used in applications where the water supply to the pump intake is under pressure. The vertical turbine is usually used in situations where the water supply is from a well, cistern, or body of water.
 (4) Electric motor (driver) and single-stage pump. The jockey pump for maintaining system pressure and very low flow is in the foreground. The relief valve is upper right. |
The driver refers to the method by which energy is provided to the pump. Simply put, a driver is the method by which energy is imparted to the pump and then into the water to supply the system. Originally, there were several “approved” drivers, which included steam, water, gasoline, diesel, and electric motors. Steam was typically used with a turbine as the driver mechanism at very large industrial complexes that used boilers and had excess steam that could be used to operate the pump. Gasoline engines were an offshoot of the automobile industry and seemed to be a natural choice. Water or hydraulic systems were associated with early energy sources and were used rarely.
Today, the two approved driver choices are diesel engine and electric motor. The driver also must have some type of controller device, the method by which the engine or motor is operated.
The electric motor controller provides the electric current to operate the motor driver and also provides monitoring of the pump operation, including the start and stop pressure monitoring. The diesel driver controller provides the method for starting the diesel engine and other features similar to those of the electric motor driver. However, whereas an electric motor may be shut down quickly after starting, the diesel motor should be allowed to reach operating temperature to reduce engine problems. Therefore, the diesel driver usually has a timer that will not permit shutting down the driver for a preselected time, usually 30 minutes. Electric motor-driven pumps must operate for a minimum of 10 minutes.
Other elements of a typical installation, such as jockey pump, relief valve, intake, discharge, test header, and control valves, are discussed below. Early controllers could only be manually operated; an employee had to be designated to manually start the pump if a fire alarm was received. The advent of the automatic controller changed this: The pump could be started automatically in response to a fire or potential fire. Typically, this is accomplished by a sensor’s monitoring the pressure within the system side of the pump; a drop in pressure caused by an open sprinkler head or a hose valve will cause the pump to start.
FIRE PUMP INSTALLATION COMPONENTS
In addition to the pump, driver, and controller, there are other important elements of the installation.
• Jockey pump. To prevent the main pump from being started and stopped unnecessarily, the jockey pump is designed to maintain the pressure in the system. This pump can produce high pressure but very low volume. Thus, the jockey pump maintains the pressure in the system when there is a minor loss of pressure from small leaks or because of changes in pressure within the system. However, because of the low volume produced by the jockey pump, the operation of a single sprinkler head is sufficient to lower the pressure beyond the jockey pump’s capability and activate the main fire pump.
• Hoses. Hose connections are provided for two functions. The typical siamese connection for augmenting the water supply is upstream of the pump intake. The test header, downstream of the pump discharge, can be used to test the performance of the fire pump by measuring the flow and pressure. In typical installations, there is one 21⁄2-inch discharge for every 250 gallons of the pump’s capacity-thus, a 1,000-gallon pump would have four hose connections. Many of the newer installations are equipped with a flowmeter that gives a direct reading of the pump’s output flow. These installations may not have a test header.
• Intake and discharge points. The pump intake and discharge points have specific design specifications. On the intake side, the pipe is usually flat or level across the top and usually conical on the discharge side. The flat pipe section reduces the potential for introducing air into the pump because of the hydraulic flow of water. The air could cause the pump to lose prime and cause serious damage. The water control valve on the intake side must be an OS & Y style, which allows the gate to be completely removed from the intake stream. Other portions of the system typically have butterfly valves. If a butterfly valve were used on the pump intake side, the valve’s rubber gasket could be torn loose and become lodged in the pump intake at the impeller.
• Control devices. Two main control devices are on the controller panel. The controller is usually found in the automatic mode, but the setting can be changed to manual. This enables the driver to start manually for test purposes or if the pump does not start in the automatic mode. There is also an emergency feature that makes it possible to start the pump driver in emergency situations, such as when the pump fails to start automatically during a fire.
• Driver protective features. There are some protective features for drivers, such as circuit breakers. However, they can usually be bypassed under fire conditions. The idea is that it may be better to keep the motor operating and take a chance on burning up the driver or damaging the pump instead of losing the building because of a mechanical problem. Only the basics of pump installation are covered here; the intricate elements are beyond the scope of this article. Properly investigate each installation you encounter prior to a fire.
WATER SUPPLIES FOR FIRE PUMPS
The two basic sources of water supply are the municipal water system and static supplies. A connection to the pump intake, separate from the domestic connection to the building, is the most common source. This connection’s size is based on flow tests of the municipal water supply (to determine the available supply). The pressure of the municipal water supply is added to that produced by the pump, which results in a combined, or discharge, pressure.
Static water supplies are usually in the form of a surface or an elevated tank, but they can also be a cistern or wet well built in a stream, a canal, or a body of water. Split-case horizontal fire pumps are most often employed with surface or elevated tank static supplies, where some pressure is provided to the intake side of the pump because of the elevated tank or pressure from the water elevation in a surface tank above the pump’s intake point. Although it is possible, by using a foot valve, to use a split-case horizontal pump with a surface water supply, the vertical turbine pump is most commonly used. This installation is similar to that of submersible pumps in that the pump bowls are submerged in the water supply and the driver is at the end of the shaft at the top of the installation. These pumps are most commonly used with wet wells; however, they can be used with installations that are taking suction from an aquifer ground water source.
When a tank is used, it is relatively easy to determine the water available for firefighting operations. If the tank holds 50,000 gallons and is connected to a pump capable of delivering 1,500 gallons per minute, the water supply can be counted on for a period of approximately 33 minutes. Obviously, if the actual flow is less than the maximum, the duration may be longer, say 100 minutes at 500 gallons per minute. However, if the pump is producing in excess of its rated capacity, the duration may be much shorter. As an example, a 1,500-gpm pump must be able to deliver 150 percent of its rated capacity, or 2,250 gpm maximum. In this situation, our 50,000-gallon static water supply would run out in approximately 22 minutes. More about pump capacities will follow.
The point is, when you have a finite water supply, there is some point at which the supply will be exhausted. If the fire is out before or at that point, there is no problem. If it is not, you must have another plan. Therefore, when preplanning properties with fixed water supplies, determine if a tanker shuttle system should be incorporated in the incident management plan. If you make this decision after the water supply has been exhausted, the fire probably would have considerably advanced before the supply could be replenished and you may never recover. Simply stated, you need to know the pumping capacity and the static water supply available in gallons as part of your prefire plan. In the situation with supply from natural water sources, you usually will not have to worry about running out of water. However, if your area experiences a prolonged drought, the surface water may be considerably lower than normal. A final reminder: Fire pumps cannot produce water; they can only provide the needed pressure at a required flow capacity.
TESTING AND MAINTENANCE
Because of the nature of fire pump installations, testing and maintenance are critical. Since the pump operates only if there is a fire, that is not the time to find out it is not working properly. After installation, an initial pump acceptance test is required. This is performed to determine if the pump will operate as designed. The pump must be able to meet the following points on the performance curve:
• The pump must show that it will not exceed 100 percent to 140 percent (for vertical turbine pumps) of the rated pressure at zero flow (in gallons).
• The next point is 100 percent of its rated flow at 100 percent of its rated pressure.
• At 150 percent of its rated flow, the pressure should not be less than 65 percent of its rated pressure.
Example: A pump is rated to provide 1,500 gallons per minute at 100 psi. The pump should produce no more than 100 percent (horizontal split case) to 140 percent (vertical turbine) of the rated pressure at zero flow-1,500 gpm at 100 psi and 2,250 gpm at 65 psi (minimum).
As part of the initial acceptance, these points should be plotted on a hydraulic graph paper and should prove the pump performance and serve as the basis for evaluating future flow tests. This test must be repeated annually at a minimum. Any significant deviation from the design capacity can indicate problems that should be investigated. A weekly churn test (operating the pump without flow) is required (Figure 1). You can program the timer on the pump controller to initiate this test automatically. However, someone should check the pump conditions and verify that the pump started. Electric motor-driven pumps should operate for five minutes and diesel motors for 30 minutes to reach operating temperature. These weekly tests are conducted with no flow, using the relief valve to keep the pressure within the system from becoming excessive. For other inspection and testing requirements, consult National Fire Protection Association (NFPA) 20, Standard for the Installation of Stationary Fire Pumps for Fire Protection, and NFPA 25, Inspection, Testing, and Maintenance of Water-Based Fire Protection Systems.
FIRE DEPARTMENT OPERATIONS
When planning for responses to properties that use fire pumps as part of the fixed fire protection system, you must be certain to address some specific issues, such as the following.
In your prefire plans, identify the location of the pump room. Document the pump’s location as well as some basic information such as the pump’s capacity, the water supply source, the type of driver, and accessibility.
One of the first-arriving units should be assigned to access the fire pump room, to determine if the pump is operating. If it is not, and there is a fire, the pump can be started manually using the control panel. The individual assigned to this position should have a radio and should remain at the pump room until the incident has been concluded or the individual is relieved by another firefighter. Firefighters stationed at this location may feel they are not contributing to the handling of the incident; however, this position is critical. The outcome of the combat operations depends on the water supply to the fire sprinklers-if the yard mains supplying fire department operations and the pump should fail, the fire could rapidly overwhelm the suppression activity.
During such a failure, the firefighter might be able to restart the pump; at the very least, he would be able to advise the incident commander that this vital element, the water supply system, has been lost. At this point, steps can be taken to replace the fixed fire pump with an engine company.
One final note: Shutting down the fire pump before the fire has been completely extinguished can have the same effect as closing a sprinkler valve too soon. The fire can rekindle, and a delay in placing the pump back in operation could be enough to allow the fire to exceed the capability of the fixed suppression system. At the conclusion of the fire, a licensed contractor should inspect the pump assembly to make certain that it is put back in the standby mode and that no damage has occurred.
DIESEL VS. ELECTRIC PUMPS
The steam- and gasoline-driven pump installations are no longer recognized by agencies that approve pump installations. Reliability is the key factor that caused the shift to diesel and electric pumps. The public utility supplying the building or complex also supplies the electric pumps. It is not required that there be a separate electric company feed to ensure the reliability of the electricity supply to the pump. Therefore, if there is a general loss of power to the area, such as during a storm, there will be no electricity supply for the fire pump. In some situations, diesel generator sets (gensets) might be installed to provide backup power for the fire pump. However, this is not required and is done only in situations where reliability is critical; in such situations, the insurer requires the installation because of the nature of the risk. Although generators are not required in all situations, property owners should be encouraged to provide backup electric service. In some instances where the property is in an area with access to two separate power grids, the pump installation may include an automatic transfer switch that will automatically change the power supply to the grid that has available power if power to the other is lost. This increases reliability; however, if both grids experience a power loss, the pump will not operate. The firefighter assigned to the pump room must be aware of the transfer switch and know how to operate it so he can verify that the switch is closed and is receiving power from the “hot” grid.
Diesel pumps are more reliable if they are properly maintained, particularly in rural areas where electric power supply is more likely to be interrupted. They have their own power supply in the form of the diesel engine driver and a fixed fuel supply. However, this reliability brings with it a greater demand for maintenance. Just like the water supply from a fixed tank or source with a finite water supply, the fuel tank has a limit based on its fuel capacity and the driver’s consumption rate. Check the tank regularly to ensure that it is properly filled. The firefighter responding to the pump room should verify the fuel level and be able to determine the pump’s approximate running time. If the fuel level is low, someone should be called to come fill the tank. For this reason, it is important to have phone contacts available so refueling can be called for whenever needed.
The diesel driver must also have an internal heating unit so that the block will be kept at the proper operating temperature during fall and winter months. If the engine block is too cold, it may not start. Batteries are another maintenance concern. If they are not maintained, the starter will not be able to automatically start the engine as designed. There should be ready access to an emergency power source that can supply power to the batteries/starting circuit to start the pump manually when the batteries cannot. Most of these situations will not occur if you have an adequate preventative maintenance program. Keep in the pump room records that show all of the required maintenance items. A lack of such records or incomplete records put the pump’s reliability in question, and this information should be communicated to the incident commander or the water supply officer.
WHY PUMPS FAIL
According to a Factory Mutual survey, the most common reasons for pump failure included the following:
• A manual pump was not activated in response to a fire (40%);
• An automatic pump was impaired prior to the fire’s beginning (30%);
• The electric power failed (13%);
• The water supply was impaired (13%); and
• The pump failed during loss (various reasons) (4%).
This information reinforces the importance of proper preventative maintenance and testing as well as the need to monitor the pump during operations. Many years ago, I was evaluating the fire protection system at a multimillion-dollar convention complex. As part of this process, the fire pump installation was examined. It was determined that the pump installation was never tested in the five years since it had been installed. It is of great concern that a pump installation could be ignored for such a long period.
During the witnessing of a pump test in Georgia, the pump’s aged electric motor was started and had been running for 10 minutes when the building owner asked if that was enough time and if it could be shut down. We answered, “Not yet.” After 20 minutes, the main pump panel shorted out, causing immediate pump failure. The building owner was angry that the pump was operated until it failed. It was explained that had this failure occurred during a time when that pump was needed to fight a fire, the outcome would have been disastrous. In the end, he agreed that it was better to find out about the pump conditions prior to an emergency.
When visiting a hospital complex undergoing renovation, it was discovered that the water supply on the intake side of a fire pump had been shut completely, yet the electric power to the pump controller was still in the “on” position. When it was pointed out that had the pump operated with the water supply shut there would have been an almost instantaneous catastrophic failure of the pump, there were some red faces-better a little embarrassment than damaging a $100,000 pump installation.
These are just a few examples of how pumps can be impaired. Unless you see detailed reports that reflect periodic pump operation and test results, assume that the pump can fail at any time. This is important to know if your fire combat operations are dependent on the sprinkler system or a pump-supported water supply. Not only can there be extensive property damage or even a loss of life because of the pump’s failure, but you would also have to alter your combat operations to reflect reliance on the fire department water supply only. Treat any deficiency in the pump operation as an impairment of the fire protection system.
PUMP ACCEPTANCE AND TESTING
When a pump assembly (pump, driver, and controller) is completed, the manufacturer will conduct a shop test if it is seeking approval from Underwriters Laboratories (UL) or FM. This will produce documents relative to the pump’s performance. The documents are delivered to the installing contractor and become part of the installation records. This information is then used as the benchmark for performing the acceptance test after installation and all future tests. It is important to have access to this information when conducting fire prevention inspections and managing a fire situation.
THE FUTURE: FIRE PUMPS AND FIREFIGHTING
It is highly likely that fire pumps will become more and more common. In significantly developed areas, achieving adequate water pressure in municipal mains can be challenging. As demand for pressure increases, particularly in high-rise buildings, fire pumps will continue to provide the solution. It would be highly advantageous to incorporate training on fixed fire pump operations as part of your combat training program. Most pump manufacturers are enthusiastic about assisting with such programs. You must feel comfortable with these installations. When you first look at them, they appear as a maze of pipes, valves, and controls. Once you understand the basic elements of these installations, you will be able to quickly determine the details of the systems you encounter. But remember, the time to become familiar with fire pumps and their operation is before they are needed to combat a fire. ■
Bibliography
Fire Protection Handbook, Eighteenth Edition, National Fire Protection Association, 1997.
Understanding the Hazard – Fire Pumps, FM Global, 2000.
■ DAVID R. BLOSSOM, ALCM, CFPS, CFI1, is a certified fire protection specialist, a certified fire inspector, and an associate in loss control management from the Insurance Institute of America. He has an extensive background in the insurance industry as a loss control specialist and consultant in fire protection. He is chairman of the Fire & Life Safety Code Board of Adjustments and Appeals for Orange County, Florida, and past vice chairman for the City of Orlando Fire & Building Code Appeals Board.
