Multiple Diurnal Evaporative Emissions Determinations with a Naturally Controlled Variable Volume Enclosure

The successful operation of a naturally controlled variable volume enclosure is dependent upon the ability to adjust volume in response to controlled cyclical temperature changes, as well as asynchronous ambient pressure changes. The ability to naturally adjust internal volume is affected by the physical and operational design of the enclosure. Natural control of volume adjustment is done without the use of any physical control systems and relies solely on the effects of internal enclosure temperature and pressure to operate. The purpose of this paper is to explain the design, construction, and verification issues used not only in constructing such a variable volume enclosure but also in proving the hydrocarbon mass retention integrity of such an enclosure.