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Knowledge of clean bench contamination sources

       1. Dust generation

　　The amount of dust inside the clean bench, from the equipment can be considered through the local exhaust exclusion, does not flow into the room; products, materials, etc. in the delivery process of dust and human dust compared to the amount of general very small, can be ignored; due to the application of the metal half-wall (colored steel sandwich panels) from the surface of the building of the dust is also very small, generally accounted for less than 10% of the dust is mainly from people, accounting for 90% or so. In the amount of dust from people, due to the improvement of clothing materials and styles, the absolute amount of dust is also decreasing.

　　A, material: cotton dust is the largest, the following order of cotton, indeed good, de-static pure polyester, nylon.

　　B, style: large hanging type of the largest amount of dust, the upper and lower split-type followed by the least full-cover type.

　　C. Activity: the amount of dust in the action generally reaches 3-7 times the rest time.

　　D. Cleaning: the amount of dust generated by washing with solvents is reduced to one-fifth of that of washing with general water.

　　Indoor maintenance structure of the surface dust, subject to the ground, about the corresponding 8 square meters of the surface of the ground when the amount of dust and a stationary human dust equivalent.

　　2. Bacteria

　　Staff generated pollution:

　　(1) skin: human beings usually every four days to complete a complete skin removal, and human beings every minute to shed about 1000 pieces of skin (average size of 30 * 60 * 3 microns)

　　2) Hair: human hair (diameter of about 50 to 100 microns) is shed all the time.

　　3) Saliva: including sodium, enzymes, salt, potassium, chloride and food particles.

　　4) Everyday clothing: particles, fibers, silica, cellulose, various chemicals and bacteria.

　　5) Humans will produce 10,000 particles larger than 0.3 microns per minute at rest and sitting and standing.

　　(6) Humans will generate 1,000,000 particles larger than 0.3 microns per minute when they move their heads and torsos.

　　(7) Humans walking at a speed of 0.9m/s will produce 5000000 particles per minute greater than 0.3 microns.

Clean bench

　　Analysis of foreign test data can be considered:

　　(1) Clean the bench when the staff wears aseptic clothing:

　　The amount of bacteria at rest is generally 10-300 / min.

　　General activity of the body of the bacteriological output of 150-1000 / min.

　　900-2500 organisms/min. a person when walking at a fast pace.

　　(2) Coughing: 70-700 organisms/min. per person.

　　Sneeze: 4000-62000/ min. per person.

　　(3) When wearing normal clothes, the amount of bacteria is 3300~62000/ min. person

　　(4) The number of bacteria without mask: the number of bacteria with mask 1:7~1:14

　　(5) The amount of germs: the amount of dust 1:500~1:1000 According to domestic examples:

　　(6) The amount of germs generated by the personnel during the operation is 878 per minute.

　　Therefore, it can be seen that the static bacterial emission of the personnel in the clean bench in sterile clothing is generally not more than 300 / min. person, the dynamic bacterial emission is generally not more than 1000 / min/person, as a basis for calculation is feasible.