What is the maximum allowable water delivery time for a dry pipe system protecting an Ordinary Hazard Group II occupancy?

According to NFPA 13, Standard for the Installation of Sprinkler Systems, the maximum allowable time for water delivery to the system test connection in a dry pipe system is determined by the hazard classification of the protected occupancy. For Ordinary Hazard occupancies, which includes both Group I and Group II, the standard mandates that water must be delivered in not more than 50 seconds. This time limit is critical to ensure rapid fire suppression and to mitigate the inherent delay in water delivery associated with dry pipe systems, preventing excessive fire growth before the sprinklers can discharge water.

A. 40 seconds: This is not a specified time limit for any standard hazard classification for water delivery in NFPA 13.

B. 45 seconds: This is the maximum allowable water delivery time for an Extra Hazard occupancy, which has a higher fire risk.

D. 60 seconds: This is the maximum allowable water delivery time for a Light Hazard occupancy, which has a lower fire risk.

1. National Fire Protection Association (NFPA). (2022). NFPA 13: Standard for the Installation of Sprinkler Systems. Section 8.2.3.2.2. Quincy, MA: NFPA.

Quote: "For Ordinary Hazard occupancies, the sprinkler system shall deliver water to the system test connection in not more than 50 seconds."

2. National Fire Protection Association (NFPA). (2019). NFPA 13: Standard for the Installation of Sprinkler Systems. Section 8.2.3.2.2. Quincy, MA: NFPA.

Quote: "For Ordinary Hazard occupancies, the sprinkler system shall deliver water to the system test connection in not more than 50 seconds."

3. Mowrer, F. W. (2005). ENFP 429: Fire Protection Systems - Sprinkler Systems Lecture Notes. Department of Fire Protection Engineering, University of Maryland.

Content Reference: Course materials covering dry pipe system design requirements directly reference and explain the water delivery time criteria from NFPA 13, Section 8.2.3, specifying the 50-second limit for Ordinary Hazard occupancies.