EPA regulations (40 CFR Part 279) as well as certain state regulations, set limits for the level of total halogens in used oil to be recycled into new oil or burned as fuel. This is done to reduce the emissions of hazardous chlorinated solvents and their by-products, including hydrochloric acid. Although EPA and ASTM field methods developed specifically for measuring the total halogen content are available, for cost reasons, many oil recyclers use hand-held refrigerant leak detectors to screen the oil by measuring the headspace above the oil and using this measurement to estimate the oil phase concentration. Since the regulations do not require that testing be performed, only a certification of the quality of the oil, which may be based on process or other knowledge, any test method may also be used. The results of an evaluation of the effectiveness of leak detectors in screening used oil for total halogens are presented. In comparison with EPA laboratory and field methods, the leak detectors were unable to detect halogens in oils contaminated with low volatility halogenated species such as those found in cutting oils and PCBs, even at percent levels. The leak detectors also produced an excessive number of false negative responses for volatile halogenated species in testing at low temperatures (0-32F) and under windy conditions likely to be found in field situations. Many false positives were also found due to gasoline and oxygenated solvents fkequently found in used oil such as acetone and MEK. Because the leak detectors are an unreliable tool for screening used oil, the recyclers should use the EPA or ASTM methods. Recommendations are given for creating financial incentives to encourage recyclers to switch to the EPA methods.
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