Pass the NFPA Water-Based Systems Professional CWBSP Questions and answers with ExamsMirror

Standard weight pattern malleable iron fittings that are 6 inches in size and smaller typically have a maximum pressure rating of 300 psi (21 bar). This rating ensures that the fittings can withstand the pressure demands of most fire sprinkler systems without failure.

References: Fitting manufacturers provide specifications for malleable iron fittings, including their pressure ratings, which must comply with standards such as those set forth by ASTM and ANSI.

Areas containing diesel engine drive fire pumps and day tanks represent a higher fire risk due to the presence of flammable liquids and operational equipment, typically necessitating at least an Extra Hazard Group I classification to ensure adequate fire protection.

References: NFPA 13's approach to hazard classification, which considers the nature and combustibility of materials present, as well as the specific risks associated with operational equipment.

The equivalent length of a 45° elbow for 6 in Schedule 10 pipe is often considered to be around 11.8 ft, accounting for friction loss and the impact on water flow. This equivalent length helps in hydraulic calculations to ensure the sprinkler system meets the required design criteria for pressure and flow.

References: NFPA 13 and hydraulic calculation principles used in the design and installation of sprinkler systems, including considerations for pipe fittings like elbows.

In a building with an ordinary hazard occupancy and a roof slope as described, calculating the number of sprinklers on a branch line typically involves considering the spacing and the slope's impact on coverage. For 11.5 ft on-center spacing, calculating six sprinklers on a branch line would provide adequate coverage without exceeding maximum spacing requirements.

References: NFPA 13 guidelines on sprinkler spacing and placement, particularly in buildings with sloped roofs, to ensure effective coverage and distribution of water in the event of a fire.

You can see in the above equation that if Q is raised to the power of 1.85 in the above equation, this has the effect if the flow is doubled and all other factors remain constant, the friction loss would increase by almost four times. If the flow were to triple, the friction loss would almost be nine times greater. You can also see that the pipe diameter D is raised to the power of 4.87 and is in the denominator on the right-hand side of the equation. Therefore any increase in the pipe size will reduce the friction loss if all other factors remain the same. If the diameters double, the friction loss will be reduced by almost a factor of 1/32 likewise, if the pipe diameter is tripled, The friction loss would be reduced to about 1/243 of its original value.

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Group A plastics, even when stored on racks, present a high challenge to sprinkler systems due to their high heat release rates. The given design criteria, especially the density of 0.495 gpm/ft² over an area of 2000 ft², might be suitable for controlling fires in Group A plastic commodities stored to the specified height, considering the use of high-temperature rated sprinklers (286 degrees) which are typically used in high-challenge fire scenarios.

The jockey pump stop point is typically set slightly above the fire pump start point to prevent unnecessary cycling of the fire pump. If the jockey pump start point is at 165 psi, the stop point should be higher to maintain system pressure and prevent overlap with the fire pump activation threshold, making 175 psi a suitable stop point.

References: NFPA 20 and CWBSP materials, which cover the installation and testing of fire pumps, including jockey pumps, recommend setting the jockey pump's stop pressure above its start pressure to ensure seamless system pressure maintenance.

Post Indicator Valves

6.3.1

Where post indicator valves are used, they shall be set so that the top of each post is 32 in. to 40 in. (800 mm to 1.0 m) above the final grade.

For a dry sprinkler in a freezer with an internal temperature of -20°F and an external ambient temperature of 40°F, a minimum exposed barrel length of 18 in. is typically recommended. This length helps prevent freezing within the barrel while accommodating temperature differentials.

References: Installation guidelines for dry sprinklers in environments with significant temperature variations, ensuring system functionality and freeze protection.