What does PurityPlus Certification Mean?PurityPlus® producers are an organization of Independently Owned Specialty Gas producers in North America working through the Independent Welding Distributors Cooperative. A fundamental part of the PurityPlus program is it's consistent Standard Operating and Quality Assurance Procedures that all producers must pass. Our exhaustive SOP/QA program was originally designed, tested and coordinated by AsteRisk, LLC., a gas-industry consulting company administered by a long-term employee of Union Carbide/Praxair. PurityPlus® continues to endorse AsteRisk for its third-party auditing, as well as operations and safety consulting. http://www.asteriskllc.com/ Elemental to the program are an array of levels or tiers that define the proficiencies of each member. These tiers define the process and analytical capabilities necessary to supply gases of defined purities, aligning with generally accepted impurity maximums and analytical tolerances. For example, all certified PurityPlus® producers can package and certify nitrogen and argon to grade 5.0 (ultra high purity.) Moving up in the tiers usually involves the purchase of further analytical and gas-filling equipment to fill higher purity atmospheric gases. Calibration and verification is carried out through NIST-traceable standards, most typically SRM’s, and substantiated by annual round-robin testing.