What does PurityPlus Certification Mean?PurityPlus® producers are a body 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 satisfy. Our thorough SOP/QA program was originally designed, tested and implemented by AsteRisk, LLC., a gas-industry consulting company overseen by a long-term employee of Union Carbide/Praxair. PurityPlus® continues to utilize AsteRisk for its third-party auditing, as well as operations and safety consulting. http://www.asteriskllc.com/ Essential to the program are an array of levels or tiers that define the capabilities of each participant. 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 designated 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.