PERC

Tetrachloroethylene [127-18-4] perchloroethylene, CCl2=CCl2, is commonly referred to as "perc" and sold under a variety of trade names. It is the most stable of the chloriaated ethylenes and ethanes, having no flash poiat and requiring only minor amounts of stabilizers. These two properties combiaed with its excellent solvent properties account for its dominant use ia the dry-cleaning iadustry as well as its appHcation ia metal cleaning and vapor degreasiag. 

Butyryl choline iodide [(2-butyryloxyethyl)trimethyl ammonium iodide] [2494-56-6] M 301.7, m 85-89", 87", 93-94". Recrystd from isoPrOH or Et20. [Tammelin Acta Chem Scand 10 145 1956.] The perc/i/orate has m 72° (from isoPrOH). [Aldridge Biochem J 53 62 / 953.]... 

T. Main, Inc., Healtli Risk Assessment for Air Emission of Metals and Organic Components for tlie Perc Municipal Waste Energy Facilities , PERC, Boston, MA, 1985. 

Smith, D., Tong, J. and Leigh, G., Combined effects of caffeine and tobacco on the components of choice reaction time, heart rate and hand steadiness. Perc and Motor Skills 45(2), 635-639, 1977. 

Precip. Perc. Precip. Perc. Precip. Perc. Precip. Perc. Precip. Perc. Precip. Perc. 

The ALCD has collected data on percolation using lysimeters and soil moisture to monitor cover performance. Total precipitation (precip.) and percolation (perc.) volumes based on 5 years of data are provided in Table 25.6. The ET covers generally have less percolation than the Subtitle D cover for each year shown. More information on the ALCD cover performance can be found in Dwyer.39... 

Perc A process for making a heavy fuel oil by reacting a slurry of biomass in aqueous sodium carbonate solution with carbon monoxide. Under development in the United States in 1980. 

The aqueous-phase pyrolysis can also be assisted by catalysts and reactive gases. For instance, the PERC process [3, 33] produces a pyrolysis oil upon dissolving wood chips in a recycle pyrolysis oil, mixing the slurry with a water-Na2C03 solution and treating the resulting mixture at 370 °C and 275 bar under synthesis gas atmosphere. 

PERC (Tetrachloroethylene) Industrial Solvent Prolonged Exposure above 1500 mg/ M3 Surface of vegetables 10-30 days... 

Perchlorate Strain perc lace Herman and Erankenberger (1999)... 

The solvent perchloroethylene (PERC) is used by approximately 90% of all EU dry cleaners today. ... 

It is likely that greater uptake of alternative technologies to dry-cleaning with PERC has been hindered by a combination of factors including -... 

Improving efficiency of PERC dry cleaning machinery Equipment manufacturers are able to offer advanced machinery complying with the stricter emission control standards, to the extent that the consumption of PERC has reduced by more than 50% since 1980, and in some countries 90% - misguided efforts that could have been better directed towards removing this toxic substance totally. 

The fact that regulations required users of PERC to meet emission limits, ratherthan substitute PERC by investing in alternative technology, meant that few dry cleaners were bold enough to convert to new methods. A variety of safer substitutes have existed for over a decade that the Canadian and US governments have independently monitored. Both studies confirmed the economic and environmental benefits and technical feasibility of these alternatives. 

A recent EU-funded study examined the operation of 2 full-scale liquid carbon dioxide (LCO ) pilot units in Denmark and the Netherlands, based on 38 different textile materials and 9 different garment types. The study identified several advantages of LCO textile cleaning compared to perc dry cleaning ... 

Less damage to coatings or laminates that swell with perc ... 

However, the majority of dry cleaners continue to use perchloroethylene because there is little awareness and no legislative imperative to choose safer substitutes." With both wet cleaning and CO now available in Europe and commercially competitive, there can be no Justification for the continued use of PERC to clean clothes. 

Pentyl ethanoate, see sec-Amyl acetate sec-Pentyl ethanoate, see Amyl acetate Penwar, see Pentachlorophenol Peratox, see Pentachlorophenol Perawin, see Tetrachloroethylene PERC, see Tetrachloroethylene Perchlor, see Tetrachloroethylene Perchlorethylene, see Tetrachloroethylene Perchlorobenzene, see Hexachlorobenzene Perchlorobntadiene, see Hexachlorobutadiene Perchlorocyclopentadiene, see Hexachlorocyclopentadiene Perchloro-l,3-cyclopentadiene, see... 

Statfjord atmospheric resid (1). Atmospheric resid (2). SRC II (3). Prahoe shale oil (4). Directly liquefied oil from wood chips using the PERC process (5). Molar ratio adjusted assuming that ammonia, water and hydrogen sulfide are formed by the heteroatoms. 

The oil derived from biomass was liquefied with the PERC process, extracted with decalin, hydroprocessed at 370 0, and the fraction boiling above 350 C (BMO) was separated by distillation (16). A hydroprocessed mixture of North sea and Arabian light vaccum gas oil (HVGO) was used as a "base line", i.e. a typical FCC feed stock. 

At one time, the dry cleaning industry relied on petroleum products for their cleaning agents. Currently, the single most popular solvent used by dry cleaners is a compound called perchloroethylene, widely known by the nickname of perc. About 30,000 dry cleaners in the United States alone use perc for their cleaning operations, accounting for about 80 percent of all such cleaning done in the country. 

Patrick principle The principle that the quality of a body of water and the changes caused by human activities on that water can be determined by the type and number of organisms found there. The principle is named after microbiologist Ruth Patrick, perc An abbreviation for a commonly used dry cleaning fluid, perchloroethylene. 

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