Prepared by:Douglas B Horne, P.E.Clean Vehicle Education Foundationwww.cleanvehicle.orgAugust 31, 2012
The growth of natural gas vehicle (NGV) fleets in recent years, especially for those vehicles in interstate commerce, has increased the need for additional gaseous fuel friendly maintenance facilities across the country. The NGV industry has largely focused its efforts on development of vehicles and fueling infrastructure, while leaving issues dealing with the design and operation of maintenance facilities to fleet owners. The fleet owners have used their internal staff and/or consultants to interpret the intent of the applicable codes to develop a facility design for liquefied natural gas (LNG) and/or compressed natural gas (CNG) applications that will be approved by the authority having jurisdiction (AHJ). This is sometimes a difficult process since the codes are “performance” documents (provide little design guidance) and use language such as, “areas subject to ignitable concentrations of gas”, which requires expert evaluation of expected hazardous conditions. Guidance that provides a better understanding of the intent of the code committee when the language was drafted is needed in order to apply those requirements to the diverse (ceiling height, layout, roof construction, heating, ventilation electrical etc.) design of maintenance facilities.
This document looks at the modifications necessary for existing liquid fuel maintenance facilities to service both CNG and LNG vehicles. The basic national codes are outlined and the rational and/or assumptions used to develop the codes are discussed. It is important to note that an individual existing maintenance facility must be evaluated to determine any necessary modifications since the building design and activities performed in the facility can have a significant impact on the modifications required.