Manufacturers of rigid polyure-thane foam in the U.S. have a little more than four years to find new blowing agents to replace their current product of choice, hydrochlorofluoro-carbon (HCFC)-141b (CH_3CFCl_2). However, while the pressure to act is mounting, no clear replacement has emerged. Hydrofluorocarbon (HFC)-245fa (C_3H_3F_5), once poised as the leading candidate to replace HCFC-141b, seems like less of a sure thing today. Other products are being tested, but none offers all the benefits of 141b.
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