Vaporizers control systems

Detonation arresters are typically used in conjunction with other measures to decrease the risk of flame propagation. For example, in vapor control systems, the vapor is often enriched, diluted, or inerted, with appropriate instrumentation and control (see Effluent Disposal Systems, 1993). In cases where ignition sources are present or pre-dic table (such as most vapor destruct systems), the detonation arrester is used as a last-resort method anticipating possible failure of vapor composition control. Where vent collec tion systems have several vapor/oxidant sources, stream compositions can be highly variable and... 

The key components in the fuel vapor control system include the fuel tank, vapor vent valves, vapor control valve, vapor tubing, the activated carbon canister, and the engine vapor management valve (VMV) [25,26], During normal vehicle operation, fuel tank vapor pressure is relieved through the use of vapor vent valves installed in the vapor dome of the fuel tank. The vent valves are designed to allow for the flow of fuel vapor from the tank, and to assure that liquid fuel does not pass through the valve. 

A key parameter in the design of the fuel vapor control system is the volume of activated carbon required to meet the emission standards for the various regulatory tests. In the case of the three-day diurnal test sequence, the emission limits are 0.05 grams of HC per mile during the run loss portion of the test (maximum emission -0.85 grams), and a maximum release of 2.0 grams for the sum of the hot soak period and any one of the three 24-hour periods making up the diurnal test sequence. 

A vehicle fuel vapor control system must be designed to meet both driving and refueling emission level requirements. Due to the nature of hydrocarbon adsorption, this emission control is a continuous operation. 

CER Part 154, Subpart E-Vapor Control Systems. 1990. U.S. Department of Transportation, U.S. Coast Guard. 

White, R. E. and Oswald, C. J. 1992. Mitigation of Explosion Hazards of Marine Vapor Control Systems. Southwest Research Institute, Final Report, SWRl Project No. 06-4116 for the American Petroleum Institute, Washington, DC (October 1992). 

Seebold, J. G. 1992. Detonation Arresters for Marine Vapor Control Systems Status of Research and Uncertainties—Where from Here Paper presented at a Colloquium on Vapor Control Systems Detonation Arrester Research and Testing, July 23, 1992, Health and Safety Executive, Buxton, Derbyshire, England. 

A special study [74] was commissioned by the American Petroleum Institute (API) entitled Mitigation of Explosion Hazards of Marine Vapor Control Systems. The report examines the effects of deflagradons and detonations in pipes in the region of detonation flame arrestors. The primary objective was to resolve potential... 

The design of the vapor control system was inadequate, including the lack of flame arrestors. 

FIG. 26-25 Possible positions at which flame arresters may he placed (vapor control system). 

Detonation Arrester Testing Requirements are described by various agencies in the aforementioned documents (UL 525, etc.). For installations governed by the USCG in Appendix A of 33 CFR, Part 154 (Marine Vapor Control Systems), the USCG test procedures must be followed. These are similar but not identical to those of other agencies listed (for a discussion of differences, see Deflagration and Detonation Flame Arresters, 1993). 

The CTG document recommends a single volatile organic compound (VOC) emission limit for loading of gasoline tank trucks at terminals. To comply with the limit, an active vapor control system must be installed to condense, absorb, adsorb, or incinerate the VOC vapors. Control equipment to fulfill this requirement is presently commercially available. However, a good maintenance and inspection program must minimize leakage from the vapor control system and tank trucks. 

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