Potential replacement for ozone killer.

Potential replacement for ozone killer

An international treaty taking effect this July 1 will require the United States and 31 other ratifying countries to freeze their production and consumption of certain ozone-destroying chemicals at 1986 levels -- a first step in a process that will cut use of these chemical, called chlorofluorocarbons (CFCs), in half by the year 1999. Last week, the world's largest producer of CFCs, E.I. du Pont de Nemours & Company, announced its development of chemical blends that may easily replace the most widely used CFC.

Chemists at Du Pont have mixed together a newly developed compound called HCFC-124 along with two already available chemicals, HCFC-22 and HFC-152a. These mixtures are designed to replace CFC-12, a common coolant in air conditioners and refrigerators. Although these new blends pose some threat to ozone, Du Pont says, they are 97 percent less damaging to stratospheric ozone than CFC-12.

Du Pont and others have already developed alternate replacements for CFC-12, but the leading replacement candidate does not rival CFC-12 in energy efficiency (SN: 4/9/88, p.234). Based on laboratory work, Du Pont claims the new blends can perform as well as CFC-12, and that they might work in existing equipment with little change in design--a characteristic that would make the switchover less costly.

Other CFCs are used for blowing foam insulation and cushioning and for cleaning printed circuit boards.

It will take several years of testing by the industries using CFC-12 to tell whether the new blends can actually fill in for the older product. Moreover, the EPA must approve HCFC-124 for sale, a process that could take four years, says Tony McCain, alternatives development manager for Du Pont's Freon Products Division in Wilmington, Del.