With the development of science and technology, especially military industry, aerospace industry, electronics industry and biomedicine industry, the development of air dust-free room and dust-free workshop technology is constantly developing. Modern industrial products and scientific experiment activities require miniaturization, precision, high purity, high quality and high reliability. In order to produce these products, it is necessary to achieve the corresponding level of air cleanliness in the controlled production environment and the corresponding ultra-pure water, ultra-pure gas and ultra-pure reagents with high purity in direct contact with the products. Next, we will briefly introduce the pollution sources of dust-free rooms and workshops, which mainly refer to the following two categories: micro-dust and bacteria.
1. [External Pollution Sources]
Concentration of atmospheric dust
Atmospheric dust is the object to be treated directly in the dust-free chamber. In the dust-free technology, the counting concentration is usually based on the number of particles (> 0.5 um). In the clean stratosphere (10 km from the surface), such particles have about 20 particles/L, and there are about 2600 particles/L above the clean sea surface. There are great differences in the counting concentration on land and in different time in the same area. The atmospheric counting concentration in China can be roughly divided into "industrial city", "suburban city", "non-industrial area" or "rural area". The particle concentration (>0.5 micron) is 1*106 grain/L, 2*105 grain/L and 3*105 grain/L, respectively.
Concentration of atmospheric bacteria
The pollution of air dust belongs to the pollution of inanimate particles, while the pollution of air bacteria belongs to the pollution of living particles. Microorganisms include viruses, rickettsia, bacteria, fungi and protozoa. But bacteria and fungi are the main ones related to clean rooms. But bacteria can not survive alone, and generally adhere to the dust particles, so the meaningful size is its equivalent diameter. When a group of bacterial particles pass through the filter, the efficiency of bacterial filtration is the same as that of a certain particle size, then the particle size is the equivalent diameter of the group of bacterial particles.
2. [Internal Pollution]
Dust emission
The amount of dust emitted from the clean room can be removed by local exhaust from the equipment and not flowed into the clean room. Compared with the amount of dust emitted from human body, the amount of dust emitted from products and materials in the process of handling is generally smaller and negligible. At present, the cleaner interior decoration uses better metal wallboard, and the amount of dust from the surface of buildings is also very small, generally accounting for less than 10%, and the dust mainly comes from people, accounting for about 90%.
Bacterial quantity
(1) When workers wear sterile clothes in clean rooms:
At rest, the bacterial quantity is generally 10-300 per minute.
The amount of bacteria produced during general activities is generally 150-1000 per minute.
When walking fast, the amount of bacteria is generally 900-2500/min.
(2) A cough is usually 70-700 per minute.
A sneeze is usually 4,000 to 60,000 per minute.
(3) When wearing ordinary clothes, the bacterial count ranges from 3300 to 62000 per minute.
(4) Mask-free bacteria: Mask-free bacteria 1:7-1:14
(5) Bacterial quantity: dust quantity is 1:500-1:1000
(6) The number of bacteria in operation personnel: 878/min.
Therefore, it can be seen that the static bacterial quantity of people wearing sterile clothes in clean rooms is generally more than 300 per minute, while the dynamic bacterial quantity is generally less than 1000 per minute.
Ed Purification has developed in the field of dust-free workshop for many years. A series of dust-free workshop purification projects have been implemented. For some difficult projects, the construction team of dust-free workshop purification project has been perfectly completed through excellent technical strength and well-trained.