[Technical] EN 14683:2014 Planar mask pressure difference test

At the beginning of the year, when communicating with customers, we got information about the resistance test of medical masks.

The common test conditions in the industry are: 32L/min flow rate, 100cm2 test area. The 100cm2 test area is the standard test area for general-purpose instruments for testing filter efficiency and resistance. Therefore, only the flow rate needs to be adjusted, and the test is carried out using a common test instrument, whether it is a test filter or a test mask.

Consulted YY 0469-2011 medical surgical mask standard 5.7, on the resistance, that is, the pressure difference test area 4.9cm2, test flow 8L/min.

See also YY 0969-2014 Standard for disposable medical masks This is defined as ventilation resistance. The test conditions are also test flow 8L/min, test diameter 25mm, and calculated area 4.9cm2.

Look at the foreign standard again, EN14683:2014 is defined here as Delta P, the test flow is 8L/min, the test area is 4.9cm2.

It appears that the test conditions for the flat face mask test resistance at home and abroad are uniform. 8L/min flow rate, 4.9cm2 test area, and whether we are domestic manufacturers of mask materials, or mask detection, are generally used 32L/min, 100cm2 test conditions, where is the difference?

Different flow rates.

The flow rate was 1.63cm/min, 32L/min at 8L/min 4.9cm2, and 0.32cm/min at 100cm2.

The flow rate is a factor that directly affects the resistance, so the test results must be different under the above two conditions. The difference between 1.63/0.32 and 5.09 times is roughly considered.

Look again, the flat mask defines the resistance Delta P = M/A, which is the result of the differential pressure table test and area ratio. The unit is the pressure difference in the area per square centimeter, Pa/cm2.

Different from the resistance test units we commonly use, there are differences in calculation methods. The resistance tested under the condition of 8L/min 4.9cm2 is larger due to the increased flow rate, but it needs to be divided by the area of ​​4.9cm2, and the result is close to the result of the 32L/min, 100cm2 test.

But note that it's just close, or it will be different.

In theory, the results of the test according to the standard method will be larger than the results of the conventional method test. If the conventional method tests the card edge product, it is easy to exceed the standard when the standard method is used .

As an instrument manufacturer with experience in manufacturing filter media, please contact:

Since the meltblown product (the main source of flat mask resistance is the meltblown fabric) is inherently limited in uniformity, it is normal for the resistance to fluctuate, and the standard method test area is only 4.9cm2, which is very small. It is a very normal phenomenon that the test results are very different. A flat mask replacement test results will be different in different locations. A roll of meltblown fabric tests different positions and the test results will be more different. If the same manufacturer's different volumes of product test results may be more different.

Therefore, truly understanding the quality of products, based on the number and frequency of sampling, will bring different results.

Then, for manufacturers who do not have the means of detection, if they only judge the quality of their own products by submitting products, there are limitations.

Recently, the car was repeatedly received notice, and all kinds of violations were fined . As an old driver of 10 years of driving experience, the deductions for the past six months have exceeded the sum of the previous 10 years. Is it because the driving level has become lower?

No, just because of the development zone in which we live, the probes at each intersection are gradually put into use. This broke the confidence that I always thought I had a good level of driving. I couldn't afford to check it.

I think the same is true for mask companies. Originally thought that the quality of their products was good, and as the country continued to strictly control the quality of its products, the market sampling, the problems will gradually reveal.

This article is reprinted from the world dust purification , the content is deleted.