Laboratory cleanroom planning, design and construction solutions

Introduction:

1. The clean room is a fully enclosed environment. Through the primary, middle and high-efficiency filters of the air-conditioning supply and return air systems, the indoor ambient air is continuously circulated and filtered to ensure that the suspended particles in the air are controlled to a certain concentration.The main parameters to be controlled in the clean room are the number of dust particles, the number of colonies, the number of air changes, pressure difference, temperature, humidity, illuminance and noise.

2. No matter how the external air conditions change, the clean room can maintain the characteristics of cleanliness, temperature, humidity and pressure that were originally set.

3. The main function of the clean laboratory is to control the cleanliness and temperature and humidity of the atmosphere that the products (such as silicon chips, etc.) come into contact with, so that the products can be tested and scientifically researched in a good environmental space. Therefore, clean laboratories are usually also called ultra-clean laboratories, clean laboratories, purification laboratories, etc.

The following are the main contents that need to be paid attention to when designing and constructing a clean laboratory :

I. Introduction of clean laboratory purification engineering plan:

1. Type: Laboratory purification projects mainly include: biosafety laboratory, P2 laboratory, P3 laboratory, HIV laboratory, PCR laboratory, animal laboratory, sterile laboratory, cell culture room, etc.

2. Usage: Laboratories mainly used for research in microbiology, biomedicine, biochemistry, animal experiments, genetic recombination and biological products are collectively referred to as clean laboratories (biosafety laboratories).

3. Composition: The clean laboratory consists of the main function laboratory, other laboratories and auxiliary function rooms.

4. Principle: It is necessary to ensure the safety of personnel , the environment, the safety of waste and the safety of samples, so that it can operate safely for a long time. At the same time, it is also necessary to provide a safe, comfortable and good working environment for laboratory staff.

5. Scheme: including building layout and decoration, water supply and drainage, electrical design, air conditioning, gas supply, centralized control, security, construction technology, testing, training and other aspects.

II. Guidelines for the layout and design principles of clean laboratory buildings

1. The architectural layout of the clean room is closely related to the purification air conditioning system. The purification air conditioning system must not only obey the overall layout of the building, but also conform to the principles of the purification air conditioning system, so as to give full play to the relevant functions.

2. The designer of the purification air conditioner should not only understand the building layout to consider the layout of the system, but also make suggestions for the building layout so that it conforms to the principle of clean room.

(1)The floor plan of the clean laboratory :

The clean room generally includes three parts: clean area, quasi-clean area and auxiliary area.

(2)The layout of the clean laboratory:

The veranda wrap-around type: The veranda can be windowed or windowless, which can be used for visiting and placing some equipment, and some windows are equipped with duty heating in the veranda, and the outer windows must be double-layer sealed windows.
Inner corridor type: The clean room is located on the periphery, and the corridor is located inside. The cleanliness level of this corridor is generally higher, even the same level as the clean room.
Two-end type: The clean area is set on one side, and the other side is set up as a clean and auxiliary room.
Core type: In order to save land and shorten pipelines, the clean area can be used as the core, surrounded by various auxiliary rooms and hidden pipeline spaces. This method avoids the impact of outdoor climate on the clean area and reduces cold and heat energy. consumption, which is conducive to energy saving.

(3)Personnel purification route

In order to minimize the pollution caused by human activities during operation, before entering the clean area, personnel must change clean clothes, shower, bathe and disinfect. These measures are called “ personnel purification” or “PP” for short.
In the clean room for people, the room where clean clothes are changed should be supplied with air, and positive pressure should be maintained for other rooms such as the entrance side. A little positive pressure should be maintained for toilets and showers, while toilets and showers should maintain negative pressure.

(4)Material purification route

All kinds of objects must be purified before they are sent to the clean area, which is referred to as object purification.
The material purification route and the human cleaning route should be separated. If the material and personnel can only enter the clean room at the same place, they must also enter the clean room from different doors, and the material should be subjected to rough purification treatment first.
For occasions where the production line is not strong, an intermediate warehouse can be set up in the middle of the material route.
If the production line is very strong, a straight-through material route is adopted, and sometimes multiple purification and transfer facilities need to be set up in the middle of the straight-through route.
In terms of system design, since many raw particles will be blown off in the rough purification and fine purification stages of the material purification room, the relative clean area should maintain negative pressure or zero pressure. If the pollution risk is high, the inlet direction should also maintain negative pressure design.

(5)Pipeline organization

Clean room piping is very complex, so these lines are organized in a concealed way. The specific covert organization methods are as follows.

Top technical interlayer: In this interlayer, the section of the supply and return air pipes is generally the largest, so it is the first consideration in the interlayer. It is generally arranged at the top of the interlayer, and the electrical pipeline is arranged under it. If the bottom plate of the interlayer can bear a certain weight, filters and exhaust equipment can be set on it.
Room technical interlayer: Only compared with the top interlayer, this method can reduce the wiring and height of the interlayer, and save the technical lane required for the return air duct to back to the upper interlayer. In the lower lane, the power distribution of the power equipment of the return fan can also be set up, and the upper lane of a certain layer of clean room can also be used as the lower lane of the upper layer.

(6)Technical lane (wall)

The horizontal pipelines in the upper and lower interlayers are generally turned into vertical pipelines, and the hidden space where the vertical pipelines are located is the technical lane.
The technical lane can also place some auxiliary equipment that is not suitable for configuration in the clean room, and can even be used as a general return air duct or static pressure box, and some can be installed with a light pipe radiator.
Since most of the technical lanes (walls) use lightweight partitions, they can be easily adjusted when the process is adjusted.

(7)technical shaft

Technical lanes (walls) tend not to go over layers. Technical shafts are used when they are needed, and are often permanent as part of the building structure.
Since the technical shaft connects all the layers, in order to prevent fire, after the internal pipeline installation is completed, it should be sealed with materials whose fire resistance limit is not lower than that of the floor slab, and the maintenance work should be carried out in layers. The access door must be equipped with fire doors.
Regardless of technical interlayer, technical lane or technical shaft, when it is directly used as an air duct, its inner surface must be treated according to the requirements of the inner surface of the clean room.

(8)Computer room location

It is best for the air-conditioning room to be close to the clean room that requires a large amount of air supply, and the line of the air duct should be the shortest.
However, in terms of preventing noise and vibration, it is required to separate the clean room from the computer room.
When designing, both should be taken into account at the same time, and strive to be the best.

(9)Safe evacuation

Since the clean room is a highly airtight building, its safe evacuation has become a very important and prominent issue, and it is also closely related to the setting of the purification air-conditioning system. Generally, the following points should be paid attention to:

Safety exits: There are at least two safety exits in the fireproof area or clean area in each production floor. Only one safety exit is allowed when the area is less than 50㎡ and the number of people is less than
Evacuation exits: People net entrances should not be used as evacuation exits. Because people’s net routes are often tortuous. Once the fireworks are obsessed, it is very difficult to ask people to run outside quickly.
Bypass door: The air shower room cannot be used as a general access channel. Since this kind of door is often two-leaf interlocking or automatic, once it fails, it will affect the evacuation greatly. Therefore, a bypass door is generally set in the air shower room, and this gate must be set up when there are more than 5 people. Usually, when the staff leaves the clean room, they should not walk through the shower room but through the bypass door.
Opening direction: Considering the need to maintain the indoor pressure condition, the doors of each clean room in the clean area should be opened in the direction of the room with high pressure as the door must be pressed tightly by pressure, which is obviously the opposite of the requirements for safe evacuation. In order to consider the two aspects of cleanliness and emergency evacuation, it is stipulated that the doors between clean areas and unclean areas, and the doors between clean areas and outdoor areas are treated as safety evacuation doors, and their opening directions are all towards the evacuation direction. Of course, the same is true of a single security door.

III. Clean laboratory design specifications:

(1) Design specification for clean workshop GB50073

(2) Clean room construction and acceptance specification JG71

(3) Design specifications for clean workshops in the electronics industry GB50472

(4) Design specifications for clean workshops in the pharmaceutical industry GB50457

(5) Technical Specification for Construction of Hospital Clean Operating Department GB50333

(6) Disinfection management measures
(Note: The above regulations are subject to the latest version)

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).