What does PurityPlus Certification Mean?PurityPlus® producers are a group 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 comprehensive SOP/QA program was originally designed, tested and implemented by AsteRisk, LLC., a gas-industry consulting company organized 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 an array of levels or tiers that define the proficiencies of each partner. These tiers define the process and analytical capabilities needed to supply gases of defined purities, aligning with generally accepted impurity maximums and analytical tolerances. For example, all qualified PurityPlus® producers can package and certify nitrogen and argon to grade 5.0 (ultra high purity.) Moving up in the tiers usually requires the purchase of additional analytical and gas-filling equipment to fill higher purity atmospheric gases. Calibration and verification is accomplished through NIST-traceable standards, most typically SRM’s, and authenticated by annual round-robin testing.