In this paper, we review shelf-life studies on several ESGs and discuss the fundamental issues of chemistry and physics related to the purity of ESGs as a function of both time and usage of the cylinder. We show that, in almost all cases, the shelf life of an ultrahigh purity ESG packaged in a well-prepared and passivated cylinder is at least 2 to 3 yr. The performance of cylinder valves is also a key concern regarding the shelf life of the cylinder package. The purity, integrity, and functionality of the cylinder valve must be maintained over the shelf life of the product. The results of lifetime testing of the functionality and particle cleanliness of cylinder valves are shown. The tests show that the purity and functionality of the cylinder valves in corrosive gas service can be maintained for at least 2 to 3 yr if proper gas-handling procedures are used. These procedures are the single most important factor in determining the lifetime of a cylinder valve in corrosive gas service.

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