WEBQUALITY : Towards a Tool Supporting the Assessment of Web-Based Applications Quality.

A method for purifying crude argon containing argon, oxygen and nitrogen comprises the steps of reducing the amount of nitrogen in the crude argon to between a trace and 0.15% (by volume) and passing the remaining oxygen and argon, together with residual nitrogen, through 4A molecular sieve to separate the oxygen and argon. The 4A molecular sieve is particularly effective if steps are taken to ensure that all the remaining oxygen and nitrogen has to pass through a volume of 4A molecular sieve which is wholly at or below -250 DEG F.