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Views: 9 Author: Site Editor Publish Time: 2023-03-21 Origin: Site
1. Background
At the beginning of 2020, COVID19 pandemic started from Wuhan . Filter material testing becomes very necessary and important.
It also called PFE (particle filtration efficiency) test. It means how many percentages of particles are blocked by filter material in a mask
We used to do some tests, the result as below
The PFE value for towel is about 20-25%
The PFE value for Normal fabric is also about 20-25%
This means only 20-25% particle, i.e. virus could be blocked by a mask with normal fabrics or towel.
If H11 melt-blown fabric, its PFE is about 95%
N95 mask, its PFE is about 95-97%
Why N95 mask can be such good performance of PFE, as in N95 mask, there are 1-2 layers melt-blown fabric in side, see below
So from the test above, you may understand melt-blown fabric is very important for N95 Mask.
2. About testing & tester
How to do a test for the filter material or the whole mask?
In EN 143 or EN 149 or GB2626 (Chinese standard) or ASTM D2100,
There are two types of tests
a) NaCl Aerosol test
b) Oil Aerosol test
In these two types of tests, need two different generators to produce NaCl Aerosol or Oil Aerosol, and make one of them to penetrate the test specimen, mask or filter material.
How to count how many particles penetrate through the mask or filter material? There are two methods,
One is laser particle counter, another one is photometer.
If a lab strictly follows EN143 EN 149, they should use the second method, i.e. they should use photometer to detect the particles concentration.
But most of other test methods do not specify which sensor the lab should use, either laser particle counter or photometer.
Before Jan-2020, in China, not more than five makers which produce PFE tester (filter material tester), but now, more than 20 companies produce this type testers
a) PFE tester (filter material tester) with particle counter sensor
Like our model AFT-100 Face Mask PFE tester
b) PFE tester (filter material tester) with photometer
Like our model AFT-140 mask particulate filtration efficiency tester
Another important spare parts in these testers, it is Generator for NaCl aerosol or oil aerosol.
In EN143, there is some requirement for these two types of aerosol. So Generator is very important component of this testing machine.
In brief, in these testers, photometer (Laser particle counter) and Generators are the two important components, as they are too much related to testing result and life-time of the machine.
For example, now some suppliers, the Generator of NaCl Aerosol is made by 304 stainless steel, we found it must get rusted after 2-3 weeks use.
Some photometer (or Laser particle counter ) in some machines with good designing or arrangement, it may be out of order after2-3 month use, buyer has to purchase a new photometer (or Laser particle counter)
TSI is really good brand from USA for such a tester. most of the biggest commercial lab use its tester for PFE.
1. How to select a right model between AFT-100 or AFT-140?
What is difference between AFT-100 Face Mask PFE tester or AFT-140 mask particulate filtration efficiency tester
ITEM | AFT-100 | AFT-140 |
Particle sensor | Particle counter*1 | Photometer*2 |
Oil aerosol Generator | Stainless steel | PTFE |
NaCl aerosol Generator | PTFE | PTFE |
Pressure sensor brand | China | France |
Control Panel | LCD screen | Computer |
Air source | Centrifugal Ring blower | Air compressor |
From our experience,
1. AFT-100 PFE tester is an economic model, it can be applicable for mask testing, for some mask producer, commercial lab with limited budget, university or research institute, etc.
2. AFT-140 Automatic filtration efficiency tester is a high end tester, as its testing result can be compliable with TSI machine, most of the buyer are from melt-blown fabric producer, famous commercial lab, big brand mask maker, etc.
You also can visit our website EN143 Automatic Automated Particulate Filter Efficiency PFE Tester AFT140 - Buy Particulate Filtration Efficiency Tester, PFE Tester, Test PFE Product on Abest Tester Group (abest-tester.com)
OR https://fyitester.com/for-sale/automated-filter-tester-aft-140/
