1.1.1 This guide applies to the design, location, installation, maintenance, and use of devices and systems that vent the combustion gases and pressures resulting from a deflagration within an enclosure so that structural and mechanical damage is minimized. A deflagration can result from the ignition of a flammable gas, mist, or combustible dust. 1.1.2 This guide should be used as a companion document to NFPA 69, Standard on Explosion Prevention Systems, which covers explosion prevention measures and can be used in place of, or in conjunction with, NFPA 68. The choice of the most effective and reliable means for explosion control should be based on an evaluation that includes the specific conditions of the hazard and the objectives of protection. Venting of deflagrations only minimizes the damage that results from combustion. 1.1.3 This guide does not apply to detonations, bulk autoignition of gases, or unconfined deflagrations, such as open-air or vapor cloud explosions. 1.1.4* This guide does not apply to devices that are designed to protect storage vessels against excess internal pressure due to external fire exposure or to exposure to other heat sources. 1.1.5 This guide does not apply to emergency vents for runaway exothermic reactions or self-decomposition reactions. 1.1.6 This guide does not apply to pressure relief devices on equipment such as oil-insulated transformers. It also does not apply to pressure relief valves on tanks, pressure vessels, or domestic (residential) appliances.