What does PurityPlus Certification Mean?

PurityPlus® manufacturers are a group of independently-owned specialty gas producers in North America that are working through the Independent Welding Distributors Cooperative. Our regularly-performed Standard Operating and Quality Assurance Procedures are an essential aspect of the PurityPlus program. AsteRisk, LLC, a consulting organization in the gas industry, is the company that originally defined, evaluated, and carried out our extensive SOP/QA program. AsteRisk is further endorsed by PurityPlus for its third-party auditing, in addition to its operations and safety consulting. The fundamental aspects of the program are a set of levels or tiers that defines each participant’s performance capacity. These tiers lay out the analytical abilities and processes that are necessary to provide gases of stated purities by adhering to generally approved levels of maximum impurity and analytical tolerances. Additionally, calibration and verification is implemented through standards that are NIST-traceable and confirmed by annual testing.

What is traceability?

We use two definitions when attempting to define traceability. The first is the NIST definition, which says that traceability is described as an uninterrupted record of documentation (“documentation traceability”) or an uninterrupted chain of measurements and associated uncertainties (“metrological traceability”). When applied here, the word “traceability” always refers to “metrological traceability.” The ISO 17025 definition of traceability is “a property of a measurement result whereby the result can be related to a reference through a documented unbroken chain of calibrations, each contributing to the measurement uncertainty.” The specialty gas specification at PurityPlus can be traced back to NIST’s Standard Reference Materials where similar gas standards exist. If certain SRM’s are nonexistent, equally comparable standards are used, directly sourced from a national government agency outside of the United States, or by having a gas standard reviewed and certified by NIST or another designated entity.

What is the difference between a single-stage and a dual-stage regulator?

Single-stage regulators reduce pressure in merely one step to generate pressure within a specified range. Regulators created accordingly will display an insignificant variation in delivery pressure as the cylinder pressure decreases when in use. Because of this, single-stage regulators are most suitable for applications in which a constant outlet pressure is not vital, where an operator can monitor and readjust pressure, or where an inlet pressure is stable.

Dual-stage regulators perform the same function as single-stage regulators; however, delivery pressure holds constant as cylinder pressure declines. Heightened accuracy in pressure control is maintained because the reduction of pressure is achieved in two steps. Dual-staged regulators are recommended for applications that require a constant outlet pressure for the life of a gas cylinder.

Download our catalog for more information on gas regulators or locate a PurityPlus partner in your area.

What does having PurityPlus primary / certified standards mean?

PurityPlus® Specialty Gases offers several grades of calibration gas standards – Custom Mixtures, Certified Standards, and Primary Standards to meet the level of accuracy for your laboratory or production process. All PurityPlus Specialty Gases are custom-mixed and analyzed, and then properly labeled in one of our independently audited laboratory facilities. Each PurityPlus Production facility conforms to a strict set of quality-assurance measures and standard operating procedures. Each of these labs have been thoroughly inspected, certified and documented to be compliant with FDA, DOT, OSHA, and EPA requirements - among others - by AsteRisk, a globally known, reputable, independent certification company headquartered in the U.S. 

Exposure to hazardous chemicals results in steep fines, penalties, and a compromised workforce. PurityPlus Specialty Gases meets regulations and ensures compliance with all primary and certified standards.


Please contact us with general questions or call 877-81P-PLUS (877-817-7587) and a representative will respond to your request within one business day. For immediate assistance, locate your local partner.