Medical face mask is widely used as personal protective equipment to protect user from airborne particles as well as liquid contaminant. Numerous test methods have been developed to classify the performance of medical face mask, which includes of the material performance on bacterial filtration efficiency, water repellent/absorption capability, flammability, differential pressure etc.
Bacterial Filtration Efficiency
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. 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.
Test Method: ASTM F2101
Specification: ≥ 95%
The Flammability test procedure evaluates the flammability of medical textiles including face masks, surgical gowns, and drapes.The Flammability test determines the time of flame spread for the given material. All fabrics of natural or regenerated cellulose, as well as certain types of finished and unfinished fabrics made from other natural or synthetic fibers, are combustible. Some combustible fabrics are potentially dangerous to the wearer because of the speed and intensity of flame with which these fabrics burn and their ease of ignition.
Test Method: 16 CFR Part 1610
Specification: Class 1 (burn time is > 7s)
Differential Pressure (Breathability)
The Delta P test is performed to determine the breathability of masks by measuring the differential air pressure on either side of the test article using a manometer, at a constant flow rate of 8 L/min.
Test Method: MIL-M-36954C
Specification: < 5 mm H2O / cm2
The outer-most layer should be water-resistant (Hydrophobic) , and the middle layer, which is used to trap bacteria, should not be too porous. The innermost layer has to be able to absorb moisture such as saliva, mucus and sneeze droplets.
Test Method: Water dripping Test
Specification: Outer layer (Hydrophobic) Inner layer (Hydrophilic)