English
Spanish
French
German
Arabic
Hindi
Korean
Russian
Dutch
When laboratory workers deal with pathogenic microorganisms, experimental materials containing pathogenic microorganisms, or parasites, in order to ensure that the experimental objects do not cause biological hazards to humans, animals and plants, and that the surrounding environment is not polluted by them, the design of laboratories and animal laboratories and construction have special requirements. According to the degree of hazard of the experimental objects, biosafety laboratories are generally divided into four levels, of which the first level has the lowest requirements for biosafety isolation, and the fourth level is the highest. Among them, Level 3 and Level 4 belong to high-level biosafety laboratories, sometimes also called biosafety clean rooms, which are often referred to as P3 and P4 laboratories.
In recent years, many scientific research units, colleges and universities, hospitals, commodity inspection and health and epidemic prevention departments have built or are about to build biosafety laboratories. Due to the strong professionalism of the biosafety laboratory, coupled with the imperfection of corresponding norms and standards in my country, and the lack of relevant experience of the builder, there are inevitably some problems in the construction. Here are some precautions for the reference of owners, design units and construction units of biosafety laboratories.
Biosecurity
1 Economic Aspects
(1) For high-level biosafety laboratories, due to their high cost, it is not appropriate to blindly compare construction to avoid waste. Before setting up a project to build a biosafety laboratory, one should first have a thorough understanding of the main purpose of the laboratory, the basic performance indicators, and the purpose of building the laboratory. The level of biosafety laboratories should be determined according to the hazards of the test objects, and high levels cannot be blindly pursued, because the higher the level, the higher the construction and operation costs.
(2) To balance the relationship between initial investment and operating costs, we should not only pursue a very low initial investment, choose cheap equipment or simple system forms, and ignore operating costs, so as to avoid problems that can be built but not used. embarrassing situation. The life cycle costing analysis method should be carried out during the design, and a reasonable and economical design scheme should be selected after technical and economic analysis.
2 Encountered The Strongest Rainfall On Record
(1) Due to the increasing number of units that want to build biosafety laboratories, some companies that have little knowledge of biosafety laboratories also want to squeeze into the construction market of biosafety laboratories. However, due to the particularity of biosafety laboratories, especially a series of special requirements in terms of technology and biosafety, it is difficult to build a biosafety laboratory without building a high-level biosafety laboratory or knowing little about biosafety laboratories. Qualified biosafety laboratories are produced, resulting in a waste of manpower and material resources.
Although some informal units take advantage of low-price competition to seize the market and have achieved some engineering performance, performance does not mean professionalism, and low price does not mean high quality. Their so-called engineering performance can only be negative pressure laboratories at best, and safety It is a far cry from a highly sensitive biosafety laboratory.
(2) At present, there are not many domestic enterprises capable of undertaking the design and construction tasks of high-level biosafety laboratories, so users should be particularly cautious when choosing contractors. Enterprises that have designed or built high-level biosafety laboratories and have relevant qualifications should be selected, which is responsible for themselves and the society. In particular, it should be emphasized that the air purification and negative pressure control system of the biosafety laboratory is much more important than the general heating ventilation and air conditioning system, and detailed design calculations must be carried out.
(3) In recent years, some foreign companies have also built some three-level biosafety laboratories in China, some of which are successful, but some of them have certain defects, mainly because of their understanding of the technical points of biosafety laboratories Not very clear. Therefore, although they used many high-grade and expensive building materials, they still did not meet the requirements. There are also some small companies that use the brands of foreign companies, and the design drawings they provide are essentially ordinary negative pressure laboratories, which cannot meet the requirements of biosafety laboratories at all.
3 Plane Layout
An overly cumbersome layout can only increase the inconvenience in use, but cannot really play much practical role; copying the simple layout of foreign laboratories does not conform to China’s environmental characteristics and management level. Due to the unreasonable layout of some actual projects, the initial investment and management difficulties have been increased, and some have affected the air cleanliness in the laboratory. Therefore, a perfect and reasonable layout is very important, which requires the owner and the designer to have a full understanding of biological safety and full communication with each other.
4 Air Conditioning And Ventilation Systems
(1) Some designers are not clear about the concept of biosafety, resulting in unreasonable air flow organization and excessive dead angle in the biosafety laboratory. The biosafety laboratory requires that the air flow must flow from the clean area to the polluted area. The position of the indoor air supply and exhaust outlets should minimize the stagnant space of the air flow, and the indoor air exhaust should be set in the most dangerous area, arranged on one side, and must not There are obstacles. In some projects, the air supply port blows towards the biological safety cabinet, and the air supply airflow and the protective airflow of the working window of the biological safety cabinet interfere with each other, which aggravates the leakage of pathogenic factors.
(2) The sealing performance is poor, including the sealing of the laboratory enclosure and the sealing of the air-conditioning ventilation duct. The poor sealing of the enclosure structure is mainly in the doors and windows, and the joints of some partition walls are also poor in sealing; the production process of air-conditioning and ventilation ducts does not meet the requirements, and the sealing materials are unqualified. These are contrary to the basic principles of high biosafety laboratories requiring good airtightness.
(3) The filter installation position of the exhaust system is unreasonable. Installing the high-efficiency filter on the positive pressure end of the exhaust fan cannot meet the negative pressure requirement of the polluted exhaust section.
(3) The exhaust system does not add high-efficiency filters, but uses high-altitude exhaust, which is also not allowed. Some design or construction units also have problems with the understanding of high-speed discharge. They think that high-speed discharge means that the wind speed in the exhaust pipe must exceed 13 m/s. Negative pressure required. Or the pressure head of the exhaust fan is increased, and the noise and power consumption are also increased at the same time. Some projects have caused conflicts with surrounding residents due to excessive exhaust noise.
(4) Replacement and leak detection of high-efficiency filters, especially exhaust high-efficiency filters. Exhaust air high-efficiency filters must be disinfected and sterilized before replacement. The design and installation must consider disinfection issues and facilitate replacement. In order to ensure environmental safety, the exhaust HEPA filter should also consider the possibility of leak detection, or take other measures to ensure no leakage. Many P3 laboratories in our country have not done this.
(6) Install split air conditioners or vertical cabinet air conditioners indoors, which is not allowed in biological clean rooms, because the heat exchanger in the air conditioner is actually a microbial breeding device, which seriously pollutes the laboratory environment. Although some construction units do not install split air conditioners or vertical cabinet air conditioners in the laboratory, they install them in adjacent rooms and use air ducts for air supply. However, because high-level biosafety laboratories must use DC air, and the heat exchanger of ordinary air conditioners is designed according to indoor circulating air, which cannot meet the large enthalpy difference required by DC air. In addition, in order to reduce the cost, the equipment capacity is not rich. The required room temperature cannot be reached at all. Experiments in high-level biosafety laboratories need to wear special protective clothing, sometimes in multiple layers. If the temperature does not meet the requirements, the experimenter’s feelings will be imagined.
In addition, there are even more ironic examples, such as building a three-level biosafety laboratory into a positive pressure laboratory, not installing fire dampers in accordance with regulations, using clean workbenches instead of biological safety cabinets, and using the exhaust of safety cabinets to Instead of room exhaust, etc., these are serious mistakes. Ordinary purification workbenches are completely different from biological safety cabinets in terms of working principle and purpose, and cannot protect the human body from microbial infection at all, which is very dangerous.
The above are just some examples, from which we can see the chaos in the domestic biosafety laboratory construction market. In order to prevent these phenomena from happening, in addition to formulating relevant normative standards so that design and construction units have “laws” to follow, corresponding management, testing, and certification institutions should also be established to ensure the construction quality of biosafety laboratories.
5 Equipment Backup Problems
(1) There is no backup power supply. For example, the three-level biosafety laboratory requires dual independent power supply, or uses a backup generator set, while the fourth-level biosafety laboratory requires a third backup power supply. If the conditions are not met, another uninterruptible power supply is required, and the power supply capacity of the uninterruptible power supply is required to be no less than 45 minutes. Some three-level biosafety laboratories only use ordinary municipal power supply without any backup measures, which obviously do not meet the requirements.
(2) Backup of the exhaust fan. In order to ensure that the laboratory maintains a negative pressure under any circumstances, the exhaust system of the third and fourth biosafety laboratories requires a spare exhaust fan, but many projects do not have it. What’s more, the exhaust system does not have a backup fan, but the air supply has a backup fan.
6 System Adjustment And Control Functions
System regulation and control functions. In order to strictly ensure the pressure difference and pressure gradient in each area of the laboratory, the necessary air volume adjustment device should be installed on the air supply and exhaust system, instead of ordinary regulating valves. The exhaust air of some engineering biological safety cabinets and rooms has not been strictly designed and calculated, and the pressure gradient required by the design cannot be met during system commissioning, or the pressure gradient is unstable.
The absence of a complete automatic control system and the lack of ability to deal with emergencies are also major problems in the completed laboratories. Although the pressure gradient of each area can be adjusted to meet the requirements during the completion acceptance, in the actual operation process, due to the change of high-efficiency filter resistance and the lack of professional operation and management personnel, laboratories without automatic control systems cannot ensure the pressure gradient. Therefore, we must pay attention to the automatic control system of the biosafety laboratory.
7 Should Pay Attention To Engineering Testing
After the completion of the entire laboratory, it should first be tested by a testing agency authorized by the state, which is a very important link. The content of the test should include the tightness of the laboratory, the negative pressure value between each room, the air flow direction, the leak detection of the high-efficiency filter, the cleanliness level, and the automatic control system.
8 Other Notes
It is strictly forbidden to build a biosafety laboratory into a positive pressure laboratory. Fire dampers should be installed according to regulations. It is strictly forbidden to use clean benches instead of biosafety cabinets, and it is strictly forbidden to use the exhaust air of safety cabinets instead of room exhaust. Ordinary purification workbenches are completely different from biological safety cabinets in terms of working principle and purpose, and cannot protect the human body from microbial infection at all, which is very dangerous.