How are The Protective Grades of The Anti Arc Clothing Classified?

The highest level of breathing, skin and eye protection is available.
Provide breathing gas (SCBA or gas pipeline); fully enclosed chemical protective clothing; inner and outer chemical protective gloves; chemical protective boots; hard caps.
The following must be worn:
It is possible to test (or possibly) have high concentration of steam, gas and dust environment; it is likely to accidentally splash, immerse or expose to steam, gas and dust, cause damage to the skin or can be absorbed through the skin; it may have a high degree of injury to the skin, and the surface cannot avoid contact to the skin at the same time; the operating environment is ventilated, A class a needs to be protected.

B level protection
The same level of respiratory protection, skin protection is the worse, and the lowest level of protection for dangerous goods.
Providing breathing gas (SCBA or gas pipe):
Chemical products, splash proof clothing; inner and outer chemical protective gloves; chemistry; hard cap.
The following must be worn:
IDLH environment (inhalation only) does not cause serious skin damage, or does not meet the condition of making filters; substances with known contact properties and concentrations require high respiratory protection, low skin protection, oxygen concentration less than 19.5%; the instrument can not fully detect steam or gas, but it is harmless to the skin or without skin absorption.

C level protection
Skin protection level is B class, low level respiratory protection:
Full air breathing respirator; chemical protective clothing; inner and outer chemical protective gloves; chemical protective boots; hard caps.
C protective clothing should be worn in the following cases:
The type and concentration of pollutants in the air are known. The filter can be effectively filtered; oxygen is not less than 19.5%; the gas environment below IDLH.

D level protection
No respiratory protection, minimum skin protection:
Conjoined suits; chemical protective gloves; chemical protective boots; safety glasses or eyeglasses; hard caps.
Wear the following cases:
There are no known harmful gases in the atmosphere; there is no possibility of liquid splashing, immersion in liquids or exposure to any harmful chemicals in the work.