Classification of masks

The National Institute of Occupational Safety and Health (NOSH new dust protection standard 42CFR84 was published on June 8, 1995 (according to the filter material

classification)

N series: no time limit for protection of non-oily suspended particles

R series: The time limit for protecting non-oily floating particles and sweaty oily suspended particles is 8 hours

P series: protection of non-oily suspended particles and oily floating particles without time limit. Some particulate carriers are oily, and these substances are attached to static

The electrical non-woven fabric will reduce the electrical properties and allow fine dust to penetrate. Therefore, the filter material for preventing oil and gas sols must undergo special electrostatic treatment to achieve

The purpose of preventing fine dust. So each series is divided into 3 levels: 95%, 99%, 99.97% (referred to as 95,99,100), so

There are a total of 9 small categories of filter media.

2. European Union EN149 Standard

FFP1: minimum filtering effect "80%

FFP2: Minimum filtering effect "94%

FFP3: Minimum filter effect "97%

3. Australian AS1716 standard

P1: Minimum filtering effect "80%

P2: Minimum filtering effect "94%

P3: Minimum filtering effect "99%

3. Japan MOL verification standard

DS2: Minimum filtering effect "99%

Ds3: minimum filtering effect "999%

4. CNS Standards in Taiwan

5. Chinese National Standard GB6223-86UDc614.894: divided into four categories

The above inspection standards are all tested with a particle size of 0.3 microns. The EU standard detection flow rate is 95L / min, and the US standard is 85min. My country

The standard suspended particle size is less than 90% of 5 microns, more than 70% of less than 2 microns, and the flow rate is 42.5L / min. In the detection and certification of filter media, it is adopted

The idea of "worst case" is taken, that is, the conditions when doing the test in the laboratory are set as the worst conditions. Such as ammonia used in efficiency experiments

The aerodynamic calculated diameter of the sodium hydroxide salt or DOP oil mist with a dust particle size of 0.3 microns, which represents the very small particles that are most likely to penetrate the filter material

The size of the granules represents the breathing volume when engaged in strong physical labor. Before the experiment, the pretreatment of the pudding material at high temperature and high humidity is also required, which represents the harsh

Working environment, the purpose of all these is to test under such harsh conditions, if the filter material can reach the corresponding efficiency level through testing, then

In practical applications, it will definitely protect workers' health more effectively. Anti-virus filter materials generally use activated carbon or activated carbon after chemical treatment

It is a material that filters toxic gas or vapor by adsorption or chemical reaction without being inhaled by people. There are many micropores in the internal structure of activated carbon

With a huge specific surface area, these micropores can inhale toxic vapors and toxic gas molecules with different molecular sizes without escaping. Treatment of activated carbon and

The installation requirements are very high. If the improper treatment or the activated carbon particles are very thick, resulting in a gap between the particles, the poison gas will penetrate through the gap and enter the

Suction, without being absorbed anymore. Therefore, it is very unscientific to replace the activated carbon in bags. Activated carbon for good chemical filter cartridges

It should be packed densely, with a small particle size and a large specific surface area, so that the anti-virus time will be long. At the same time, it must also consider the small breathing resistance and comfortable wearing. Generally come

That is to say, different types of chemical filter boxes can prevent different types of chemical substances, such as organic, acid, comprehensive anti-virus, ammonia, etc.

Masked

select

The mouth is not suitable for the crowd

1 heart or breath

People with system difficulties (such as asthma and emphysema)

2 pregnancy

3 Dizziness, difficulty breathing and sensitive skin after wearing

2. What are the characteristics of several masks on the market?

Advantages of cotton masks: repeatable cleaning and use,

Disadvantages: Saliva will remain in the part of the mask that touches the mouth and nose. If you don't clean it frequently, it will easily breed bacteria, which does not meet the hygiene requirements. cotton

The fiber of the mask is generally very thick, which cannot effectively filter the smaller particles, and most of them have not passed the international safety certification, and the protection effect is not guaranteed.

Gauze masks are almost useless, and the air leakage on both sides of the nostrils is too large.

N95 mask: used to avoid infection of the person wearing it; it is impossible to prevent the patient from transmitting the virus to others.

Surgical mask: Although it is not as effective as N95 to avoid infection, it can prevent rabbit patients from transmitting the virus to others