These requirements cover pressure relief valves intended for use in sprinkler systems for fire protection service. Pressure relief valves are intended for installation in wet pipe automatic sprinkler systems when it is anticipated that a significant increase in ambient temperature of the sprinkler piping results in the maximum service pressure of the sprinkler system exceeding the intended design pressure. Requirements for installation of these valves are included in the Standard of National Fire Protection Association for Sprinkler Systems@ NFPA 13. A product that contains features@ characteristics@ components@ materials@ or systems new or different from those covered by the requirements in this Outline of Investigation@ and that involves a risk of fire@ electric shock@ or injury to persons shall be evaluated using the appropriate additional component and end-product requirements as required to maintain the level of safety as originally anticipated by the intent of this Outline of Investigation. A product whose features@ characteristics@ components@ materials@ or systems conflict with specific requirements or provisions of this Outline of Investigation is not judged to comply with this Outline of Investigation. Where appropriate@ revision of requirements are proposed and adopted in conformance with the methods employed for development@ revision@ and implementation of this Outline of Investigation.