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The correct answer is:

A. 3 in.(75 mm)

This information can be found in several NFPA standards related to sprinkler systems, including:

•NFPA 13, Standard for the Installation of Sprinkler Systems, 2022 edition (Section 9.2.3.4)

•NFPA 13D, Standard for the Installation of Sprinkler Systems in One- and Two-Family Dwellings and Manufactured Homes, 2022 edition (Section 8.2.3.4)

•NFPA 13R, Standard for the Installation of Sprinkler Systems in Low-Rise Residential Occupancies, 2022 edition (Section 9.2.3.4)

These standards all mandate a minimum clearance of 3 inches (75 mm) between the hanger and the centerline of an upright sprinkler to ensure the sprinkler's unimpeded operation and discharge pattern in case of a fire.

It's important to note that other standards with different requirements might exist, so it's always best to consult the specific NFPA standard relevant to your situation for accurate information. Additionally, always adhere to local codes and regulations when working with fire protection systems.

Antifreeze systems equipped with a backflow preventer must include an expansion chamber to accommodate the expansion of the antifreeze solution due to temperature changes. This prevents excessive pressure buildup that could damage the system or cause unintended discharge.

References: NFPA 13 and NFPA 25 requirements for antifreeze systems in sprinkler installations, emphasizing safety features to accommodate the physical properties of antifreeze solutions.

The minimum temperature rating for ceiling sprinklers in roll paper storage areas that are 15 ft or less in height is typically 150°F (66°C). This rating is selected to provide a buffer between the ambient temperature conditions and the activation temperature of the sprinklers, preventing accidental activation.

References: NFPA 13 outlines temperature rating requirements for sprinklers based on the occupancy and storage configurations to ensure appropriate activation in the event of a fire.

The minimum flow rate for the forward flow test of a backflow prevention assembly should be the system demand plus hose stream allowance, where applicable, to ensure the assembly can handle the maximum expected flow during a fire event.

References: NFPA standards related to backflow prevention and system testing requirements, ensuring that fire protection systems can provide adequate flow under demand conditions.

For dry sprinklers, the exposed barrel length must be sufficient to prevent freezing. In extreme temperature differentials, such as from 50°F to -30°F, a longer barrel length, such as 18 inches, may be required to ensure the sprinkler remains functional.

References: NFPA 13 guidelines for the installation of dry sprinklers, considering the insulation and barrel length requirements to prevent freezing in cold environments.

According to NFPA 13, a supply of at least six spare sprinklers shall be maintained on the premises for facilities having under 300 sprinklers. Since the sprinkler system has been installed with 100sprinklers, the minimum number of spare sprinklers to be provided is six.

References: NFPA 13, 2019 edition, section 16.2.7.5(1)1; NFPA 13 Handbook, 2019 edition, section 16.2.7.5(1)2

1: https://www.nfpa.org/codes-and-standards/all-codes-and-standards/list-of-codes-and-standards/detail?code=13 2: https://www.nfpa.org/product/nfpa-13-handbook/p0013hb

When backflow prevention devices are added to a system, their associated friction losses can affect the residual pressure available for the sprinkler system operation. Therefore, it's important to account for these losses to ensure the system maintains the required pressure during operation.

References: NFPA 13 includes considerations for the installation of backflow preventers and their impact on system design, emphasizing the need to account for device-related friction losses to maintain adequate residual pressure in the sprinkler system.

The pressure at a sprinkler can be calculated using the formula P=Q²/K², where P is the pressure in psi, Q is the flow rate in gpm, and K is the K-factor of the sprinkler. Substituting the given values (Q=33 gpm, K=5.6) yields a pressure of approximately 22.3 psi.

References: Basic hydraulic principles applied in the design and analysis of sprinkler systems as outlined in NFPA 13.

A kitchen area of over 700 ft² in a restaurant typically does not meet the definition of a "small room" in fire protection terminology, as it exceeds common size thresholds for such a classification, which often consider both the area and the specific use or hazard of the space.

References: NFPA standards and fire protection guidelines often define "small rooms" based on specific criteria related to size, use, and construction features, which vary across different applications and standards.

For a high-rise building sprinklered throughout with four stairwells each having a Class I standpipe system, the maximum flow rate required to be calculated is typically 1,000 gpm (3,785 L/min). This accounts for the demand of both the standpipe system and the sprinkler system in a combined scenario.

References: NFPA 14 sets the standard for the installation of standpipe and hose systems, and it specifies the minimum flow rates required based on the number of standpipes and the type of building occupancy.