OXYGEN MEASUREMENT TO MEET MARINE HYDROCARBON VAPOR CONTROL SYSTEM REQUIREMENTS

摘要

Loading and unloading of crude oil, gasoline, benzene and other hydrocarbon products to/from tankersrnon navigable waterways is regulated by the EPA (Environmental Protection Agency) and Coast Guardrnauthorities. One major concern is the prevention of fire and detonation of flammable vapors handled byrnthe marine vapor control systems as outlined in 33 CFR 154 [1] and NVIC 1-96 [2]. Controlling thernoxygen concentration below hazardous levels, typically 8%, is critical since the hydrocarbon vaporrnconcentration can exceed lower explosive limits in air. The use of common oxygen detectors thatrnoperate at elevated temperatures (i.e. zirconia oxide or thermomagnetic sensors) are prohibited underrnthese conditions [1].rnPolarographic oxygen sensors are ideal for this application and offer several advantages over extractivernsystems:rn1. Gas-permeable membrane design eliminates the need for sample conditioning and associatedrnmaintenance.rn2. In-situ measurement assures measurement of a representative sample.rn3.Rapid response time is three times faster than recommendation.rnROI.