Grades & Purities

Most of our gases come in industrial grade, high purity and graded purity.

Industrial is the most common grade and is normally 98% to 99.9% pure depending on the gas.

Our high purity gases are normally 99.5% pure or higher.

For still higher purities, we supply cylinders with grade numbers which refer to the actual minimum purity of the gas. The grade number consists of two digits; the first digit refers to the number of 9ís in the purity and second is the final number after the 9ís. So 4.8 grade is 99.998%, 5.5 grade would be 99.9995%, 6.0 would be 99.99990% and so on. In the graded purities the maximum quantity of certain impurities, usually moisture, nitrogen, oxygen or hydrocarbon is also normally given (in parts per million or parts per billion).

Purities and availability for our industrial and high purity gases are as follows:

Product Industrial High Purity 4.5 Grade 5.0 Grade 5.5 Grade Higher Grade
Acetylene 98.6% 99.5% N N N N
Argon 99.9% N Y S S S
Carbon Dioxide 99.9% N S N N N
Helium 99.5% 99.9% Y Y S S
Hydrogen 99.5% N Y S S S
Nitrogen 99.0% 99.9% Y S S S
Oxygen 98.8% N Y S S S

Y = available ex stock, S = special order, N = not normally available

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