NFPA13D - Residential Fire Pumps
Residential fire pumps generally fall under the National Fire Protection Association's 13D codes. NFPA-13D covers the construction and installation of fire sprinkler systems for one & two-family dwellings and mobile homes.
Sprinkler demand in a residential system is normally calculated by the water flow required to run two sprinkler heads simultaneously for 10 minutes. A common flow for sprinkler heads is 15 gallons per minute. This means that a normal home with a normal system would require a 30GPM supply in order to meet code. Since standard utility company meters can't keep up a homeowner/builder has the choice of having a larger meter installed (these cost a lot, to begin with, and come with a monthly charge whether their higher capacity is used or not) or buying a water storage tank to meet the 10 minute supply demand. Water tanks are cheap and cost nothing once installed.
Water flow is only one of the factors in sprinkler demand though. The other is pressure. In order for the sprinkler head to cover enough area to be effective, it must have the water delivered with enough force(PSI). Many homes will have enough pressure. However, pressure without flow won't put out a fire. This leads back to the choice of either having a larger meter installed, along with its monthly charge, or buying a 13D system and tank. 13D systems are often much cheaper than the larger meters and cost nothing once installed.
That's where we come in. Our Home Hydrant and LSF Compact Residential Fire Pump systems are backed by years of expertise and are fully tested before they leave our facility. We also include important safety features not offered on any other system in our price range because lives depend on it. With 10 models capable of anywhere from 25 to 170 GPM flow, system pressures of up to 95 PSI, and all small enough to disappear into a corner, TALCO has your residential fire protection needs covered.
NFPA13R - Residential/Commercial Fire Pumps
NFPA-13R is the code section concerning residential buildings up to 4 stories in height. Buildings falling under this heading would include apartment complexes, mixed occupancy business/residential buildings, assisted living centers, etc. 13R regulations refer back to NFPA 20 codes which apply to any stationary pump system. As such, it occupies a sort of grey area between residential and commercial requirements.
Since 13R systems are intended for buildings up to 4 stories the pressure portion of the design condition can be in the lower range of a pump's capabilities. One of the ways pressure is measured is in head feet, literally the amount of force required to drive water vertically a certain distance in feet (Head feet/2.31=PSI). Taller buildings require higher pressures from the pump in order to push water up against gravity and the way pumps create higher pressure is by higher horsepower. So, if a system is designed for a shorter building it will require less pressure which in turn means a lower horsepower motor can be used.
The main factor involved with lower horsepower motors is the voltage and amperage on which they can run. Most residential buildings are supplied with 230 volt power which is suitable for lower horsepower motors to run with a reasonable amp draw. If the motor is 30hp or less a relatively inexpensive limited service controller can be used. 30 horsepower will cover most design conditions up to 400GPM at over 90PSI. Applications requiring only 10hp (230 volt single-phase; standard house current) can utilize an even less expensive residential controller. In short, lower horsepower leads to less expense, which is the main difference between 13R compliant systems and their more demanding, higher-powered NFPA-20 counterparts.
Almost every component in the pump system must be listed by either Underwriters Laboratories (UL) or Factory Mutual (FM), though most will carry both listings. The pump and motor are selected to meet certain performance criteria as required by the system design conditions and are tested and certified by their manufacturers before leaving the factory. Various valves are required to isolate the pump from the water supply (suction side), the sprinkler system from the pump (discharge side), to allow for regular testing of the whole system, for temperature or pressure regulation, etc. All of the fittings and pipe sections are selected to withstand system pressure and sized to allow proper flow.
Several different piping configurations are commonly employed to provide for fail-safe pump operation and required system testing. City by-pass loops and FDCs act as back-ups in case of system failure for any number of reasons. For system testing, test headers and flow meters can be utilized either individually or together on the same system, each one serving to verify the results of the other. A pump system may be required to have any or all of these configurations depending on local authorities or codes, how the system is to be installed, or what kind of structure the system will be protecting.
Our turnkey ULR Packaged Systems are designed and built in complete compliance with NFPA-20. Standard package flow rates range from 50 to 750 GPM with system pressures of up to 160 PSI. Higher flow systems (up to 1500 GPM) are available as well, but not cataloged. We can also offer water storage tanks custom sized to your specific application. Our ULR packaged fire pump systems have been installed all over North America, coast to coast and sea to gulf, with an unmatched service record.
NFPA20 - Commercial Fire Pumps
NFPA-20 is the National Fire Protection Association's code section governing the construction and installation of stationary fire pump systems. Sections of this code cover everything from requirements for system component markings to temperature or altitude specific rating changes for diesel engines. For the novice, navigating these demanding regulations can be a daunting proposition and can seem needlessly complicated. The intense attention to detail in NFPA-20 is for good reason though, it ensures that systems are built correctly and will work as intended when they are needed. Every time.
Starting from a design condition, 2500GPM @ 80PSI for example, the first task in designing an NFPA-20 compliant system is to find a pump listed for 2500GPM @ 80PSI. Such a pump will have it's suction and discharge connections sized to maintain water velocities at realistic speeds, its pressure produced at zero water flow (churn pressure) to correspond to performance criteria at 100% and 150% rated flow, provisions (depending on how it's being driven) for temperature control, pressure regulation, air release, drainage, etc. A pump rated for 2500GPM will be usable at a wide range of pressures determined by the horsepower of the driver. So for the next step, a driver is selected.
Electric motors and diesel engines are the most common choices for fire pump drivers though NFPA-20 provides guidelines for the use of steam engine drives as well. From a horsepower perspective, there is no difference between electric motors and diesel, either will work as long as they make enough power to make the pump do its job. Selection of a driver will be dependent upon where it's being installed; the resources available and possibly other equipment already on site. High horsepower electric motors run almost invariably on 460 volts or higher, 3-phase power. Using higher voltage lessens the amp draw required to develop a certain horsepower. In order to drive our example 2500GPM pump and create 80PSI the motor will need to be in the 200hp range. A 200hp motor supplied with 460-volt power will draw 250 amps running normally - with the potential to draw over 1500 amps if something goes haywire. Not every location will have enough power available or it may be prohibitively expensive. The alternative is diesel drive.
While electric motors are generally more compact than diesel, less of an environmental headache, and require fewer accouterments, they are entirely dependent on infrastructure. A diesel drive will work anywhere as long as it has fuel. NFPA-20 contains even more regulations for diesel drives than electric as provisions must be made to handle the fuel system, cooling, exhaust, vibration, etc. To satisfy a design condition of 2500GPM @ 80PSI the diesel will also have to be in the 200hp range. Once the horsepower is known, a fuel tank can be selected. One gallon of fuel capacity is required per horsepower plus an additional volume to provide room for thermal expansion. Fittings on the tank are specified for venting of fumes, containment of leaks, determining fuel level without crawling inside… Cooling methods for the diesel engine may require different set-ups for cooling water supply, return, or drain piping. Using a diesel may require installing a pressure relief valve on the discharge side of the pump in case the engine revs out of control or, regardless of driver type, if a combination of suction pressure and pump pressure rise above a certain threshold. When roughing out an NFPA-20 compliant system the designer must know how each selected component will affect the selection of another or if the installation site can support the chosen equipment. As stated above this can be a daunting, yet necessary, proposition.
We at TALCO Fire Systems, however, consider this our bread and butter. When you purchase one of our turn-key NFPA-20 fire pump packages we take full responsibility for all design and integration issues. Your installation of the complete fire pump system is reduced to connecting the main supply and discharge pipes and supplying the system with electrical power. Our custom TALCO NFPA-20 systems are designed and built from the ground up to fit your specific design conditions and site layout. These CAD designed packages are frame-mounted, fully piped, fitted, and wired. All piping sections, as well as the frame members, are powder-coated to extend service life. With your choice of either electric or diesel driven systems in capacities as high as 5000GPM TALCO has you covered.