Designers of air conditioning and refrigeration equipment have fresh guidelines for noise limits. The Air-Conditioning and Refrigeration Institute (ARI), based in Arlington, VA, publishes the new performance standard, ARI Standard 260-2001. Its title is "Sound Rating of Ducted Air Moving and Conditioning Equipment." That standard, along with 20 others, is available for free download on ARI's website, www.ari.org. Standard 260-2001 establishes a method of rating sound in indoor portions of ducted air moving and conditioning equipment. It provides definitions and requirements for acquiring mapped sound data. Sound power level calculations and ratings also are included, as are minimum data needs for published sound ratings and conformance conditions. ARI standards set rating criteria and procedures for measuring and certifying product performance. The ratings help buyers choose the proper equipment for specific applications.