What is the impact of the mask fixed way on the breathing resistance test?

Through a period of testing found that many masks on the market at present failed to test items mainly focused on filtration efficiency, breathing resistance, etc.. The paper mainly analyzes and researches the impact of wearing the mask front and back on its filtration efficiency and breathing resistance; starts from the mask breathing resistance testing, and proposes methods to solve the unstable test results brought by different fixing methods; according to the actual feedback from manufacturers, proposes how to solve the quality dilemma brought by the shortage of meltblown cloth to mask manufacturers and gives rationalization suggestions.

Generally speaking, the mask is a 3-layer structure, which is spunbond nonwoven(s) + meltblown nonwoven(M) + spunbond nonwoven(S), i.e. SMS structure. The outer layer is spunbond nonwoven with water-blocking effect, which can prevent droplets from entering the mask; the inner layer is nonwoven with softer material, which has moisture-absorbing effect and can discharge moisture from the mouth. The main part of the filtering effect is the middle layer of extremely fine and electrostatic meltblown nonwoven, the main material is high melt finger polypropylene, after electrostatic standing polarity treatment to achieve the standard required filtration efficiency.

The influence of the mask fixation method on the breathing resistance test

In GB/T 32610-2016 "technical specification of daily protective masks" in the inspiratory resistance, expiratory resistance test method, the mask in the test should be adjusted to wear position of the mask and headband tightness, to ensure that the mask and the test head mold of the tight fit. In the actual test found that the exhalation, suction resistance test value by the mask with the degree of tightness, the material of the nasal strip, head mold and mask fit, testers operating differences and other factors have a greater impact. Through the comparison study between different testing organizations, it was found that different fixation methods have a greater impact on the test results.

When worn naturally, although the mask and the head mold appear to fit together, there will still be a gap, as shown in Figure l. Since the air flow rate during the breathing resistance test was 85L/min, the airflow could easily flow out or seep in at the gap, resulting in low or unstable pressure values. The gap problem also exists in the way of fixing at the bridge of the nose and fixing at the bridge of the nose and face, so the test value is small. The effect of the gap on the test can be well eliminated when the fixation method is fixed by taping a loop around the mask. The test values are close to those of different testers using this fixation method, and the same sample has higher test stability and traceability.

Conclusion: The influence of the mask fixation method on the breathing resistance test, shared here, after reading this article you should have a basic understanding and understanding believe that we all understand it! Overall, I hope it will be helpful to you.