Nfpa 20 standard for the installation

Quality Management. SCC Standards Store. Popular Standards Bundles. Drawing and Drafting. Telecommunications Standards. AWS D1. Means, Inc. Active Only. NFPA 20 Edition, Complete Document. Includes all amendments and changes through Tentative Interim Amendment 2, December 8, Detail Summary View all details.

Price USD. In Stock. Need it fast? Ask for rush delivery. Most backordered items can be rushed in from the publisher in as little as 24 hours. Some rush fees may apply. Add to Cart. The scope of this document shall include liquid supplies; suction, discharge, and auxiliary equipment; power supplies, including power supply arrangements; electric drive and control; diesel engine drive and control; steam turbine drive and control; and acceptance tests and operation.

This standard does not cover system liquid supply capacity and pressure requirements, nor does it cover requirements for periodic inspection, testing, and maintenance of fire pump systems. This standard does not cover the requirements for installation wiring of fire pump units. The purpose of this standard is to provide a reasonable degree of protection for life and property from fire through installation requirements for stationary pumps for fire protection based upon sound engineering principles, test data, and field experience.

Complementary Documents and Links:. Active, Most Current Currently Viewing. In many high-rise buildings , this can be the automatic fire standpipe system demand which requires gallons per minute at pounds per square inch at the top of the most remote standpipe, plus gpm for each additional standpipe , up to a maximu m of 1, gpm for wet systems or 1, gpm for dry systems.

For non high-rise buildings, the most demanding area could be any number of different haz ards. Though the IBC requires buildings with a highest finished floor located more than 30 feet above the lowest fire department vehicle access to be equipped with Class III standpipes or Class I if the buildin g is fully sprinklered, NFPA 14 : Standard for the Installation of Standpipe and Hose Systems allows the standpipes to be manual type with the necessary pressure provided by the fire department pumper truck through the fire department connection NFPA 14, Section 5.

It is important to perform a hazard analysis of the building before attempti ng to size the fire pump. For example, a new sprinkler system might be installed in a five-story medical office building with a partial basement overall building height of 69 feet.

The building construction is non combustible, Type I I-B and e ach floor is approximately 18, square feet. The basement level contains electrical rooms, general storage rooms, a small oxygen storage room s quare feet enclosed by a two-hour fire rating and a covered exterior loading dock. Floors one through four are comprised of offices, exam rooms and outpatient procedure rooms.

The fifth floor is a larg e mechanical penthouse with a roof slope of 3: The center core area s on levels zero through four contain elevator lobbies , public corridor s and public restrooms. The building is equipped with a Class I wet manual standpipe system. The predominate hazard classification for the overall building is that of l ight h azard o ccupancy , h owever , the building contains spaces that warrant higher hazard designations. While the oxygen storage room requires the highest density 0.

The two-hour rated enclosure provides an effective barrier to prevent fire spread outside of the room. For this reason, the calculated area need only extend to the perimeter walls of the room NFPA 13 , Section The exterior loading dock require s the second highest density : 0. The estimated flow demand for this area is approx imately gp m 0. A preliminary hydraulic calculation for this area indicates a required system pressure of 6 5 psi.

The most hydraulically demanding area in this example is the l evel five mechanical room. Though the density for this remote area is only 0. The estimated flow demand for this area is approximately gpm 0. A preliminary hydraulic calculation indicates a required system pressure of 90 psi. Once a hazard analysis and preliminary hydraulic calculations have established the fire flow and pressure required to meet the standpipe or sprinkler system demand, a review of a recent water flow test can identify if a fire pump is necessary.

The water flow test used to size the fire pump is required to have been complet ed within the last 12 months NF PA 20 , Section 4. In the example scenario, t he water flow test indicate s pressures of 54 psi static, 48 psi residual, flowing at gpm. Typically, a minimum safety factor of 10 psi is required. Fire pumps are typically sized by pressure range, therefore a gpm pump with a revolutions per minute speed of 3 , can deliver a rated pressure from 40 to 56 psi without in creas ing the size of the pump.

Because there is no cost difference between the rated pressure of 51 and 56 psi, and high pressure is not a concern , the gpm pump rated at 56 psi is acceptable. Fire pump pressures will be explored in further detail later.

For exceptionally tall buildings , more than one fire pump may be nece ssary to deliver the pressure required to the higher floors. Fire pumps cannot opera te in parallel because the discharge check valve is forced closed when the pressure on the outlet side of the valve is higher th an that on the inlet side. Selecting a f ire p ump. Selection of the fire pump depends on the building infrastructure and available space. The most common choices for fire pump drivers are electric motors and diesel engines.

Electric motors requiring high horsepower are commonly run on volt or higher, three- phase power. Steam turbines are also an option , but are fairly uncommon. In buildings that are not equipped with enough power to supply an electric motor , a diesel fire pump may be utilized. A fuel storage tank with the capacity to hold 1 gallon of fuel per horsepower plus an additional volume to provide room for thermal expansion is required. A dike must be provided beneath the fuel storage tank to contain any potential fuel spills.

O ften, a pressure — relief valve is required on the discharge side of the pump to relieve excess pressure in the event the engine revs out of control or if a combination of suction pressure and pump pressure rise above a certain threshold.

The diesel motor exhaust must be routed through a muffler to the outside. A diesel fire pump must be located in a separate enclosure or in a room with direct access to the exterior. The enclosure size is substantially larger than normally required for an electric fire pump b ecause of the stored fuel and batteries necessary to provide a backup power source. Diesel fire pum ps are more expensive to install and maintain because of the large number of mechanical parts , which can be prone to failure.

In buildings where the electrical capacity is not a concern, an electric driver is the preferred choic e. Electric motors are more compact , require fewer mechanical parts and produce fewer negative environmental impacts. Though NFPA 20 provides guidelines for various types of pumps c entrifugal, v ertical s haft t urbine , p ositive d isplacement and m ultistage m ultiport , c entrifugal fire pumps are — including horizontal split case and vertical in-line — the most common among commercial buildings and thus highlighted in this example.

Vertical in — line pumps are generally more compact , with a smaller footprint. While horizontal split case pumps must be mounted on a concrete housekeeping pad, v ertical in-line pumps can instead be mounted on pipe stand supports. For these reasons, v ertical in — line pumps are often a preferred choic e for replacements or retrofits.

The impeller rotation in a vertical in-line pump is less susceptible to mechanical damage from water turbulence , a llow ing for more flexibility in the p iping arrangement on the suction side of the pump. H orizontal split case pumps are only permitted to have elbows and tees installed perpendicular to the pump when the fitting is located at least 10 pipe s ize diameters from the suction flange NFPA 20 , Section s 4.

Th ese requirement s are not applicable to vertical in-line styles. The impeller on a horizontal split-case pump is located in a separate casing in front of the motor , allow ing for easy access if maintenance is required. For this reason, i t is recommended that a hoist beam or another means of lifting is provided for vertical inline pumps greater than 30 horsepower. Fire p ump p ressures. The total head of a fire pump is the energy imparted to the liquid as it passes through the pump, usually expressed in psi.

For fire pumps such as horizontal split-case and vertical in-line centrifugal pumps that are required to operate under net positive suction head, the total head of a fire pump is calculated by adding the suction head city pressure to the discharge head. The discharge head of the pump varies along a performance curve that is determined by three limiting points: the shut-off , the rating and the overload.

The shut-off represents the maximum allowable total head pressure when the pump is operating at zero flow ; this is sometimes also referred to as the churn pressure. System flow demands that exceed the overload point can expose the pump to possible cavitation and damage.

Consider the previous example of a gpm pump rated at 56 psi. The available volume and pressure vary along the pump curve. Referring back to the medical building example, the loading dock required an estimated gpm at 65 psi. From the pump curve in Figure 3 , the pu mp will deliver approximately 47 psi when flowing gpm.

The churn pressure is combined with the static water pressure from the connecte d source, resulting in a combined static pressure for which all components must be rated.

If the static pressure exceeds psi the pressure rating for standard sprinkler components and maximum pressure allowed for fire hose valve connections , pressure — reducing valves may be required unless all components of the system are rated for high pressure.

It is important to include the pump churn rating in the factors to consider when weighing all of the options to make a proper pump selection. The cost of a fire pump is largely based on the horsepower rating of the pump and the type of controller. Vertical inline pumps are usually more cost effective when compared to horizontal split-case pumps in smaller sizes less than 1, to 1, gpm ratings. It is recommended to consult a local fire pump representative to compare the horsepower ratings between horizontal split-case and vertical in-line pumps , as the horsepower rating can drive up co sts related to controls and electrical connections.

Controllers NFPA 20 requires that a fire pump be supplied by a continually available power source, usually identified as an uninterrupted power source NFPA 20 , Section 9. In many cases, this requirement necessitates that a backup generator be provided as a secondary source in the event of a power failure , in which case the fire pump controller must be equipped with an automatic transfer switch.

An ATS is an option on a fire pump controller that must be specified ; a controller does not come normally equipped with an ATS. This is the default controller that will usually be supplied unless a different style has been specified. C onsult with the electrical engineer to discuss the pros and cons of the different controller styles.