ASTM (American Society of Testing: and Materials) has developed a standard for both swimming pool and Spa Covers. This Standard, ASTM F 1346-91, establishes three separate cover classifications;
In order for a spa cover to meet the requirements for a "Manual Safety Spa Cover" it must meet certain requirements which include performance tests and labeling requirements. Covers must be able to pass tests such as Static Load Tests for weight support, Perimeter Deflection Tests for entry or entrapment between the cover and the side of the spa and Surface Drainage Tests to see if a dangerous amount of rain could collect on the covers surface. There are also requirements to include labeling in consumer information (such as the warranty), and on the cover itself. Labeling must contain the proper warnings, and identify the product as a safety cover.
Non-safety covers can meet ASTM standards if they comply with the labeling requirements for "other covers". If a covers labeling does not say "safety", then it only meets non-safety cover standards. In order to legitimately bear a safety label, a cover must be able to pass the tests that satisfy the performance standards of ASTM F 1346-91.