A blunt sampling probe developed for an in situ leak test of HEPA filters in high-level biosafety laboratory

Abstract

High-efficiency air filtration is an important means of preventing harmful aerosol overflow in biosafety laboratories. For convenience in the in situ scanning leak test of a high-efficiency particulate air (HEPA) filter to ensure the filter's intactness, a cylindrical blunt sampling probe is developed. The sampling inlet is of the slot type and the inlet's length equal the width of the HEPA filter. Thus, the entire downstream face of the HEPA filter may be scanned. To evaluate the blunt sampling probe's ability to detect leaks, the scanning leak test performed on a HEPA filter unit was compared with a test using the thin-walled rectangular sampling probe that is recommended by relevant standards. Based on the comparison, the leak penetration determined using the blunt sampling probe was slightly lower than that determined using the reference sampling probe. Additionally, differences were observed according to the location that was tested. However, the blunt sampling probe could detect leaks through the comprehensive analysis of the local penetration of most-penetrating particle size (MPPS) and non-MPPS particles.