Abstract
An assessment was made of the physical state of a high containment laboratory's current HEPA filter population that is approximately 13 years old. Quantitative analyses measured the tensile strength, strain, and organic content characteristics of the filter medium of representative filters. Qualitative analysis was performed on other HEPA filter components.
Both unused stored filters and filters with 13 years of continuous service have lost 40%–45% of their tensile strength with age. Average tensile strength characteristics still exceed the relevant military standard by a factor of 1.8. The strain characteristics of all filters tested exceed the minimum criterion specified in the relevant military standard. Loss of organic content was not identified as an issue, with only one filter exhibiting significant reduction in organic content. Apart from qualitative analysis confirming that neoprene filter face seals degrade with age, no other significant problems were identified.