an air filter is a significant element of any mechanical ventilation system. however, the importance and performance evaluation of air filters have not been well publicized and related scientific reports are scarce. in this study, a transportable, off-line, air filter-testing unit (the unit) was designed and utilized to simulate the filter housing of a mechanical ventilation system. the unit wa...

Use of a portable HEPA filter cleaner in a room is believed to be capable of reducing the risk of transmission of infectious diseases through removing the particles or large droplets to which pathogens are attached. It is hoped that the portable HEPA filter(s) can increase the effective air change rate (for particle removal only) in a general ward to the ventilation standard of an isolation war...

A microbiological survey of the effectiveness of class II (laminar flow) 'safety' cabinets found in the UK in the last six years is recorded. Only two of the nine units tested approached the containment of aerosols achieved by a good class I (exhaust protective) cabinet. The others were potentially hazardous if used with pathogenic material. The National Sanitation Foundation and the British St...

The penetration result obtained on a filter test stand depends on several factors. Two of these are challenge aerosol size distribution and the particle detector used to measure the particle size and concentration. Some filter testers employ a monodisperse aerosol challenge while others use a polydisperse challenge. Some particle detectors are based on particle counting while others are based o...

Properly functioning HEPA air filtration systems depend on a variety of factors that start with the use of fully characterized challenge conditions for system design and then process control during operation. This paper addresses factors that should be considered during the design phase as well as operating parameters that can be monitored to ensure filter function and lifetime. HEPA filters us...

Field sampling has provided C. Elder, and Manuel Gonzales general criteria defining plutonium aerosol size characteristics and activity concentrations from typical plutonium operations. Two fabrication facilities have aerosols with activity median aerodynamic diameter’s (amad) ranging from 2 to 5 pm; the two research and development facilities indicate amad’s ranging from 1 to 4 ~; and a recove...