Certification

COC (Certificate of Conformation)
Contains information on the Purity of gas expressed in terms of percentage & Maximum concentration of specified impurities in terms of Parts per Million. Purity is classified in different grades and mentioned in numbers such as 4.5, where 4 before the point represents the number of nines and the 5 after point indicates the last decimal, so 4.5 = 99.995%. The actual concentration of impurities is usually lower than stated.

COA (Certificate of Analysis)
A written document that reports the analytical values obtained and certifies the concentration of the components found in a gas mixture or impurities in a pure gas and the traceability to the Reference Standard Material.

Purity Grades