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Bacterial Filtration Efficiency (BFE)

Bacterial Filtration Efficiency (BFE)

The Bacterial Filtration Efficiency (BFE) test is performed on filtration materials and devices that are designed to provide protection against biological aerosols, such as face masks, surgical gowns, caps and air filters.

This test is used for FDA 510(k) submissions for surgical masks, is required by ASTM F2100 and EN 14683, and complies with ASTM F2101 and EN14683. Nelson Laboratories staff assisted in the development of this test method, so we have more experience conducting this test than any other company. We can provide a one-stop shop for all ASTM F2100 and EN 14683 testing needs.

Applicable Standards

  • ASTM F2100
  • EN14683
  • ASTM F2101

Test Options

Ask an expert for a specific consultation on your product. If you are ready to submit your samples for testing, click here to fill out the Sample Submission Form.

Code Test Request Quote
BFE101 Bacterial Filtration Efficiency (BFE) only Add
BFE110 Bacterial Filtration Efficiency (BFE) w/ Diff. Pressure Add
BFE101 - Bacterial Filtration Efficiency (BFE) only
BFE110 - Bacterial Filtration Efficiency (BFE) w/ Diff. Pressure

Sample Specifications

BFE101: Minimum 5 recommended; each sample must be 4 x 4 inches (10 x 10 cm) flat sheet or full face mask
BFE110: Minimum 5 recommended; each sample must be 4 x 4 inches (10 x 10 cm) flat sheet or full face mask

Study Outline

The Bacterial Filtration Efficiency test determines the filtration efficiency by comparing the bacterial control counts to test article effluent counts. The test is conducted using Staphylococcus aureus as the challenge organism. After the filtration media is preconditioned for a minimum of 4 hours at 21 ± 5°C and 85 ± 5 % relative humidity, a liquid suspension of S. aureus is aerosolized using a nebulizer and delivered to the filtration media at a constant flow rate of 28.3 liters per minute (LPM) or 1 cubic foot per minute (CFM).

The aerosol droplets are drawn through a six-stage Andersen sampler for collection. The number of bacterial aerosol droplets contacting the filter media is determined by conducting challenge controls without filter medium in the test system. Challenge controls are maintained at 1700 – 2700 colony forming units (CFU) with a mean particle size of 3.0 ± 0.3 µm. This allows filtration efficiencies to be reported up to >99.9%.

The BFE test offers a number of advantages over other filtration efficiency tests. It has been used with little or no modification for years and provides a standard reference for comparison of filtration materials. The mean particle size (MPS) can be tightly controlled and is sized using a six-stage viable particle Andersen sampler, permitting stage-by-stage analysis. The BFE procedure is very reproducible, easily performed and provides a more severe challenge to most filtration devices than would be expected in normal use. Large numbers of material can be evaluated in a relatively short time.

The BFE test is commonly performed along with the Differential Pressure (Delta P) test.  
For housed filters we recommend the Increased Challenge method. This procedure uses a higher concentration of challenge to be delivered to each test material. Filtration efficiency measurements can be determined up to >99.9999%.

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