IV. Introduction of clean laboratory airflow and purification system
1. Description of laboratory purification system:
Airflow → primary effect purification → air conditioning → medium effect purification → fan supply air → pipeline → high-efficiency purification air outlet → blowing into the room → take away particles such as dust and bacteria → return air shutters → initial effect purification.... (repeat the above process)
2. Airflow form of clean laboratory:
(1) One-way flow clean area (horizontal and vertical flow);
(2) Non-unidirectional flow clean area;
(3) Mixed flow clean area;
(4) Ring/isolation device.
Remarks: The mixed flow clean area is proposed by the ISO international standard, that is, the existing non-unidirectional flow clean room is set up with a local unidirectional flow clean bench/laminar flow hood to protectt he key parts in “point” or “line” to reduce the space of the one-way flow clean area.
V. Main control items of clean laboratory purification engineering projects
1. Remove dust particles floating in the air;
2. Prevent the generation of dust particles;
3. Control temperature and humidity;
4. Adjust the gas pressure;
5. Exclude harmful gases;
6. Ensure the air tightness of structures and compartments;
7. Prevent static electricity;
8. Prevent electromagnetic interference;
9. Safety factors;
10. Consider energy saving
VI. Three commonly used purification air conditioning systems in clean laboratories
1. Direct current purification air conditioning system
(1) The DC system does not require a return air circulation system, that is, a direct delivery and straight exhaust system, which consumes a lot of energy.
(2) This system is generally suitable for allergenic production processes (such as penicillin sub-packaging process), laboratory animal rooms, biosafety clean rooms and laboratories that may form cross-contamination production processes.(3) The recovery of waste heat should be fully considered when adopting this system.
2. Full cycle purification air conditioning system
(1) The full circulation system has neither fresh air supply nor exhaust air system.
(2) This system has no fresh air load and is very energy-saving, but the indoor air quality is poor and the pressure difference is difficult to control.
(3) Generally applicable to unmanned, on-duty clean rooms.
3. Partial circulation purification air conditioning system
(1) This is the most used system form. That is to say, a system in which part of the return air participates in the circulation.
(2) In this system, the fresh air and return air are mixed and sent to the dust-free clean room. Part of the return air is used for system circulation, and the other part is discharged.
(3) The pressure difference of the system is easy to control, and the indoor quality is good. The energy consumption is between the direct current system and the full circulation system.
(4) Applicable to the production process that allows the use of return air.
VII. Clean laboratory testing and acceptance criteria:
1. Test items:
The number of dust particles, settled bacteria, planktonic bacteria, pressure difference, ventilation times, wind speed, fresh air volume, illuminance, noise, temperature, relative humidity, etc. in the clean room.
2. Refer to the testing standard:
Code for Design of Clean Workshop GB 50073
Technical Specification for Biosafety Laboratory Building GB 50346
Clean room construction and acceptance specification GB 50591
Test method for suspended particles in clean room (area) of pharmaceutical industry GB/T 16292
Test method for planktonic bacteria in clean room (area) of pharmaceutical industry GB/T 16293
Test method for sedimentation bacteria in clean room (area) of pharmaceutical industry GB/T 16294
(Note: The above regulations are subject to the latest version.)
3. Design considerations:
(1) The number of suspended particles, planktonic bacteria or settled bacteria monitored in the clean room (area) under static conditions must meet the regulations.
(2) The clean room (area) with air cleanliness level 100 should count and sample multiple times of dust particles greater than or equal to 5 μm. When dust particles greater than or equal to 5 μm appear multiple times, the test value can be considered reliable.
(3) The temperature and humidity of the clean room (area) should meet the following requirements: when the production process has no special requirements for temperature and humidity, the temperature of the clean room (area) should be 18 to 26 ℃, and the relative humidity should be 45% to 65 %.
(4) The air static pressure difference between clean rooms (areas) with different air cleanliness levels and between clean rooms (areas) and non-clean rooms (areas) should not be less than 5Pa. The static pressure difference between clean room (area) and outdoor atmosphere should not be less than 10Pa.
(5) The clean room (area) should provide illumination according to the production requirements, and should meet the following requirements:
The illuminance value of the general lighting in the main studio should be 300LUX.
The illumination value of auxiliary studio, corridor, airlock room, personnel purification and material purification room should not be lower than 150LUX.
Local lighting can be set for production parts with special requirements for contrast.
(6) The noise level (empty state) of non-unidirectional flow clean rooms should not be greater than 60dB (A), and the noise level (empty state) of unidirectional flow and mixed flow clean rooms (areas) should not be greater than 65dB (A).