VFE125 Increasing Difficulty Virus Filtration Efficiency (VFE)

The VFE125 incremental virus filtration efficiency (VFE) test follows the same procedure as the increased difficulty bacterial filtration efficiency (BFE) test, except that the challenge organism used is a bacteriophage.

Challenge controls are maintained in 3.0x0.3 plaque forming units with an average particle size of 1 plus/minus 106 µm. This allows filtering efficiencies to be reported up to 99,9999 percent. A minimum of 5 samples is recommended for these tests. Each sample should be at least 10 x 10 cm in size or a full enclosure filter.

The increasing difficulty bacterial filtration efficiency (BFE) test determines filtration efficiency by comparing bacterial control counts with test product effluent counts. The test is performed using staphylococcus aureus as the challenge organism. A liquid suspension of Staphylococcus aureus is aerosolized and introduced into the filtration medium at a constant flow rate of 30 liters per minute.

Aerosol droplets are collected in parallel on all glass measuring equipment. The challenge is given at one-minute intervals and sampling over two minutes to clean the aerosol chamber. The titer of the test liquid is determined using standard plate counting or membrane filtration techniques. The number of bacterial aerosol droplets that come into contact with the filter media is determined by performing threat checks without the filter media in the test system.

Viruses are even smaller than bacteria, with an average size of less than a millionth of a meter. Therefore, plaque-forming units are used as the standard measure of concentration in virology.

This test method offers many advantages over other filtration efficiency tests. It has been used for years with little or no modification and provides a standard reference for comparison of filtration materials. The augmented BFE procedure is very reproducible, easily performed, and presents a more serious challenge for most filtration devices than would be expected in normal use.

BFE testing is commonly performed in conjunction with differential pressure (delta P) testing.

The increased difficulty method is recommended for built-in filters. This procedure uses a higher concentration of difficulty to be delivered to each test material.

Among the numerous test, measurement, analysis and evaluation studies it provides for businesses in various sectors, our organization also provides VFE125 virus filtering efficiency (VFE) testing services of increasing difficulty, with its trained and expert staff and advanced technological equipment.