1. Quality judgment of melt blown cloth

According to the company's product standards, the quality of the melt blown cloth is judged in terms of physical indicators and appearance quality.

2. Physical index

Physical indicators include square meter mass deviation rate, square meter mass coefficient of variation (CV value), transverse and longitudinal breaking strength, transverse and longitudinal breaking elongation, deviation of single value of square meter mass, single value of transverse and longitudinal breaking strength, and transverse and longitudinal breaking elongation Rate a single value of seven items.

When judging the quality of physical indicators, first randomly sample the fabrics produced, measure and calculate each value. If it meets the corporate standard, it is the first-class product, otherwise it is the out-of-class product, and another treatment is performed, and the production process is immediately carried out. Adjust until it is qualified.

3. Appearance quality index

The appearance quality indicators include such items as turning the screen, interface, hole, rotten edge, dripping, broken wire, color difference, roll length, and width. During production, when the above appearance quality problems are found, the cloth roll shall be marked immediately and judged to be a foreign product, which shall be dealt with separately.

4. Quality Control

The cloth that has been judged to be qualified shall adopt the specified packaging method and correctly affix the specified label, and then enter the next process.

For the unqualified cloth, the reason for the unqualified cloth shall be indicated on the label, and then cut and rewinded into another specification that meets the quality requirements, or directly used as a waste product for recycling.

Important indicators of melt blown cloth

The flow rate is respectively 32L/MIN and 85L/min] resistance, and 0.3um filtration efficiency, other meanings are of little significance.

Why is the filtration efficiency of 0.3um? Because 0.3um is the most difficult to be isolated.

Particles larger than 0.3um are easily blocked by the fiber, and particles smaller than 0.3um are more likely to be electrostatically adsorbed by the fiber.

That's why we found that in the isolation rate-particle size curve, all masks have the lowest isolation rate at 0.3um. In other words, it is not that the smaller the diameter, the more difficult it is to isolate.

The filtration efficiency of 5um and 10um is not good, both are 100% or close.

Can measuring BFE and PFE be the same device? This is impossible. That is just a reference value. The real bacterial filtration is very strict in the microbiology laboratory. Even the ordinary dust salt aerosol and the bacteria are completely different.

Why does medical surgery PFE only require 30%, which is lower than civilian masks? That's because medical staff wear it for a long time and need to consider breathability, otherwise who can stand it.

We civilians can take off the mask at any time to breathe. Angels in white clothes in the operating room are absolutely not allowed, but the bacterial filtration of medical surgery must be high.