This Outline of Investigation covers requirements for the performance of antifreeze solutions for fire sprinkler systems. These solutions are intended for use in wet pipe sprinkler systems subject to freezing for installation in accordance with the manufacturer's design and installation instructions and the Standard for Installation of Automatic Sprinkler Systems@ NFPA 13; and inspected@ tested and maintained in accordance with the Standard for Inspection@ Testing and Maintenance of Water Based Fire Protection Systems@ NFPA 25.