HEPA Filter Testing

HEPA EXHAUST FILTER IV HEPA SUPPLY FILTER I / All

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...

Factors Influencing HEPA Filter Performance – 9060

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...

HEPA Filters and Filter Testing A Comparison of Factory Tests and In-Service Tests

HEPA filters, once known as absolute filters, were originally developed as the particulate stage of a chemical, biological, radiological (CBR) filtration/adsorber unit for use by the U.S. Armed Services. In the late 1940s the U.S. Atomic Energy Commission adopted them for use for the containment of airborne radioactive particulates in the exhaust ventilation systems of experimental reactors as ...

Hepa Filter Material Load Detection Using a Microwave Cavity Sensor

This paper presents a novel microwave cavity sensor application for the detection of HEPA filter particulate loading. The sensor resonates at 3.435GHz and 8.570GHz when empty, where the TM010 and TM020 modes dominate respectively. Experimental results show that the resonant frequency of the sensor shifts significantly when filters of different particulate loadings are presented to it. This is a...

Filter Paper: Solution to High Self-Attenuation Corrections in HEPA Filter Measurements