What is the minimum working pressure specified for sprinkler system piping?

What is the minimum working pressure specified for sprinkler system piping?

• A. 150 psi
• B. 175 psi
• C. 200 psi
• D. 125 psi

Answer: (B)

In sprinkler piping, the pipe must be able to handle a certain minimum service pressure—the rating tells you how much pressure the pipe can carry in use. For NFPA 13R low-rise residential systems, the minimum working pressure rating specified for sprinkler system piping is 175 psi. This provides a safety margin for pressure surges and dynamic events when water is flowing, closures occur, or transient pressures spike, even though the normal operating pressure from the water supply is typically much lower. The 200 psi figure is commonly the hydrostatic test pressure used to verify integrity, not the minimum working pressure rating. Values lower than 175 psi wouldn’t meet the standard’s required rating for this piping, and while higher ratings exist, 175 psi is the specified minimum.

In sprinkler piping, the pipe must be able to handle a certain minimum service pressure—the rating tells you how much pressure the pipe can carry in use. For NFPA 13R low-rise residential systems, the minimum working pressure rating specified for sprinkler system piping is 175 psi. This provides a safety margin for pressure surges and dynamic events when water is flowing, closures occur, or transient pressures spike, even though the normal operating pressure from the water supply is typically much lower. The 200 psi figure is commonly the hydrostatic test pressure used to verify integrity, not the minimum working pressure rating. Values lower than 175 psi wouldn’t meet the standard’s required rating for this piping, and while higher ratings exist, 175 psi is the specified minimum.