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 primary part of the PurityPlus program is it's consistent Standard Operating and Quality Assurance Procedures that all producers must satisfy. Our comprehensive SOP/QA program was originally defined, tested and implemented 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/ Integral to the program are a sequence of levels or tiers that define the qualifications of each participant. These tiers define the process and analytical capabilities required 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 more 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 verified by annual round-robin testing.