Glossary Air Changes per Hour (ACH): A measurement of the number of volumetric air exchanges within a structure caused by natural or mechanical ventilation. International Fire Code (IFC): A guidance document commonly used with, or in lieu of, NFPA 30A that covers the design of vehicle maintenance facilities and protection systems. Authority Having Jurisdiction (AHJ): Person(s) or agency responsible for reviewing, approving, and permitting proposed modifications, and issuing construction and occupancy permits. For the purposes of this document an AHJ is an agency. International Mechanical Code (IMC):
A guidance document that establishes regulations for the design and operation of mechanical systems based on prescriptive and performance-based provisions commonly used with, or in lieu of, NFPA 30A. Class I, Division 1 Electrical Hazard Zone: A zone that is expected to contain hazardous concentrations of gas or vapor in the event of a spill or leak which, therefore, must be provided with ignition source protection. Lower Flammability Limit (LFL): The minimum concentra tion of a combustible gas that will support combustion; sometimes referred to as the lower explosive limit (LEL). This is generally accepted to be 5% natural gas in air by volume at atmospheric conditions.
Class I, Division 2 Electrical Hazard Zone: A zone which may contain hazardous concentrations of gas or vapor and, therefore, must be protected. For compressed natural gas vehicle maintenance facilities, Class I, Division 2 represents conditions in which methane releases could occur but are not expected. Major Repair Garage: A maintenance facility in which major repairs are performed, such as engine overhauls, vehicle chassis and body repairs, and similar work, that require emptying the vehicle’s fuel tank. Any work that involves service to a vehicle’s fuel system also falls into this category. Compressed Natural Gas (CNG):
Natural gas that consists primarily of methane and small amounts of ethane, propane, and heavier hydrocarbons and has been compressed and stored in high-pressure vessels at pressures up to 5,000 pounds per square inch (psi). Make-up Air: Fresh air that replaces air that is exhausted from a structure. Methane (CH 4 ): The primary component of natural gas. Creditable Release: A release of natural gas within a repair garage that results in a plume of sufficient concentration that it exceeds the lower flammability limit. Minor Repair Garage:
A maintenance facility in which minor repairs are performed, such as lubrication, engine tune-ups, replacement of parts and tires, fluid changes, and similar maintenance work, that does not require emptying a vehicle’s fuel tank. Any work that involves service to a vehicle’s fuel system is not permitted in a Minor Repair Garage. Design-Build (DB): A type of contract whereby the selected contractor is responsible for the complete design of the facility, securing permits, procurement, construction, commissioning, startup, and often maintenance activities. Design-Bid-Build (DBB):
A type of contract whereby one consultant is responsible for preparing the facility design and permitting documents while a building contractor is responsible for pulling permits, procuring equipment and materials, construction, commissioning, startup, and sometimes maintenance activities. National Fire Protection Association (NFPA): NFPA is a global, nonprofit organization devoted to eliminating death, injury, and property and economic loss due to fire, electrical hazards, and related threats.
NFPA’s codes and standards are designed to minimize the risk and effects of fire by estab lishing criteria for building, processing, design, service, and installation in the United States, as well as many other countries. NFPA 30A is the basic document used in conjunc tion with maintenance facilities. Portions of NFPA 88A may also apply. Hot Work: A type of maintenance work involving the use of oxyacetylene torches and/or electric arc welders. This could also include the use of grinders or other spark- producing tools. Ignition Source: A spark, flame, electricity, static electricity, or hot surface capable of igniting a fuel that is within its combustible range. Natural Gas:
Natural gas used as a vehicle fuel is composed of 90%–95% methane and other longer-chain simple hydrocarbons. When used in the gaseous state, natural gas SEPTEMBER 2017 III