Interpretation of key quality indicators of masks (1)-filtration efficiency
Interpretation of key quality indicators of masks (1)-filtration efficiencyI. Introduction
Respirator is a kind of sanitary product, generally refers to a device worn on the nose and mouth to filter the air entering the nose and mouth, so as to block harmful gases, odors, and droplets from entering and leaving the wearer's mouth and nose. An important indicator of protective performance in a mask is the filtration efficiency of particles and bacteria. Now, let ’s take a look at how filtration efficiency works in masks!
2. What are the indicators of filtration efficiency?
According to the current mask standards, we can divide the filtration efficiency index into particulate filtration efficiency (PFE) and bacterial filtration efficiency (BFE), and the particulate filtration efficiency can be divided into non-oily particulate filtration efficiency (also known as "salt media" "Filtration efficiency") and oily particulate filtration efficiency. For the prevention of new coronaviruses in the current situation, let's take a look at the more common non-oily particulate filtration efficiency and bacterial filtration efficiency.
What is the filtration efficiency of non-oily particulate matter?
The non-oily particulate filtering efficiency refers to the percentage of the mask material to filter non-oily particulates. Through the filter layer, the mask has the function of blocking the penetration of non-oily particles. Non-oily particulates mainly refer to dusts and other particulates of different sizes. In our lives, some smaller particles can enter the alveoli and have an impact on human health. Therefore, the filtration efficiency of non-oily particulate matter plays an important role in human body safety protection. In the detection method of this indicator (GB / T 32610-2016 and YY 0469-2011), sodium chloride aerosol with a certain particle size is tested as a simulated medium to reflect the filtration efficiency of non-oily particulate matter.
What is the efficiency of bacterial filtration?
Bacterial filtration efficiency refers to the percentage of the mask material filtering out bacteria-containing suspended particles. Through the filter layer, the mask has the function of blocking the penetration of bacteria. In the detection method of this indicator (YY 0469-2011), the prepared bacterial aerosol was tested as a simulated medium to reflect the bacterial filtration efficiency.
What is the role of filtering in the mask?
Generally speaking, the mask consists of three layers, and the filtering performance is mainly determined by the filter material in the middle layer. The filter material currently used is a melt-blown non-woven fabric made of polypropylene microfibers. , At the same time can filter particulate matter in the air. The filter material is not as thick as possible. The performance of the melt-blown non-woven fabrics produced by different manufacturers varies greatly (the specific performance needs to be measured by professional equipment). Therefore, the mask can only have good filtration efficiency after it contains a layer of qualified filter material. If it is just ordinary needle-punched non-woven fabric and spunlace non-woven fabric, but no melt-blown non-woven fabric, it is difficult to achieve Good filtering effect.
Third, the difference in the index of filtration efficiency of different masks
Now, let's take a look at the difference in filter efficiency indicators in different masks (see Table 1 for details). It can be seen from Table 1 that daily protective masks, self-priming filter-type anti-particulate respirator, and medical surgical masks have non-oily particulate filtering efficiency, and different levels and types of product index requirements are also different. Disposable medical masks do not have non-oily particulate filtering efficiency indicators, but the product has bacterial filtering efficiency indicators. Masks of different standards have different requirements on filtration efficiency due to different usage scenarios and uses. Although some studies have pointed out that the filtration efficiency of non-oily particulate matter has a certain correlation with the bacterial filtration efficiency, but the type of mask is not used, and the protective effect it plays will also be very different. Therefore, when selecting a mask, it is necessary to Need to choose the right mask.
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