NSF 51 O-ring & Seal Materials:
The National Sanitation Foundation (NSF International), not to be confused with FDA or 3A, developments public health standards and certification programs that help protect the world’s food, water, consumer products and environment.The requirements are based on U.S. FDA regulations.
NSF 51 (also referred to as NSF/ANSI Standard 51) establishes minimum public health and sanitation requirements for materials used in the construction of commercial food equipment.