sprinklernotes Sprinklers in Closed Circulating Loops
The following information was provided: I am reviewing an installation of an automatic sprinkler system with non–fire protection connections in accordance with NFPA 13, 2013 edition, section 7.7. There are closed-loop water-source heat pumps that are connected to the circulating sprinkler mains and cross-mains. There is condensation occurring at the above-ceiling sprinkler piping which by dripping, is damaging ceiling tiles. You asked the following question: Is it acceptable to insulate the mains and cross mains (just the circulating portions) of sprinkler piping with non-combustible flexible cellular insulation? In response to your question(s), we have reviewed NFPA 13, Standard for the Installation of Sprinkler Systems, 2013 edition. Our informal interpretation: This is an acceptable configuration provided that the system temperature does not exceed 120°F or go below 40°F. Although this section was removed in the 2016 edition of the standard, the committee statement still suggested that the requirements in the 2013 edition would be applicable for existing systems. Per NFPA 13: 7.7.1.3 Water Temperature. 7.7.1.3.1 Maximum. 7.7.1.3.1.1 In no case shall maximum water temperature flowing through the sprinkler portion of the system exceed 120°F (49°C). 7.7.1.3.1.2 Protective control devices listed for this purpose shall be installed to shut down heating or cooling systems when the temperature of water flowing through the sprinkler portion of the system exceeds 120°F (49°C). 7.7.1.3.1.3 Where the water temperature exceeds 100°F (37.8°C), intermediate or higher temperature–rated sprinklers shall be used. 7.7.1.3.2 Minimum. Precautions shall be taken to ensure that temperatures below 40°F (4°C) are not permitted. Similar to plumbing and mechanical piping, it is acceptable to insulate pipe to reduce condensation. Because sprinklers are attached to the closed circulating loop, it is important to keep the water temperature within a range that is acceptable based on the temperature rating of the sprinkler. Ordinary-temperature sprinklers have a maximum ambient temperature of 100°F, so if the insulated pipe is designed to not exceed 120°F, intermediate temperature-rated sprinklers need to be used.
