Research on Design of Clean Environment Control System for Biological Laboratory
Biological laboratories have been widely used in many fields, such as microbial research, genetic engineering, biological experiments and related medical and pharmaceutical engineering is more and more widely used. Due to the rapid development of biological science and technology, the requirements for biological laboratories are gradually improved. Generally speaking, in a number of scientific research strength of strong pharmaceutical units widely biological laboratory for brain, heart, organ transplantation and other large surgery place, there are some medical research institutions and pharmaceutical factory also set up the relevant biological experiments Some of the related biological experiments were conducted.
一、Design of Related Technical Indexes for Biological Laboratory Clean Control
The specific technical indicators of biological laboratories in terms of relevant state departments have specific provisions for different laboratory levels have different classification, the main are the following several:
Cleanliness level parameter
Filter integrity Air flow rate Airflow organization Number of ventilation Differential pressure Relative humidity temperature
A Leak detection cycle24Month 0.25-0.50m/s
Detection cycle12Month Unidirectional flow
Detection cycle24Month The differential pressure across the zone remains constant10pa上
Once a week inspection 45-65％
Each test was tested 18-26％
Each test was tested
B 0.25-0.50m/s
Detection cycle12Month
Non - individual flow
Unidirectional flow
Detection cycle24Month
Non - individual flow Unidirectional flow
Non - individual flow
Detection cycle12Month
C - Non - individual flow Detection cycle12Month
D - Non - individual flow Detection cycle12Month
Figure 1: technical indicators of various types of laboratories
（一）Ventilation and air flow design
From the point of view of ensuring cleanliness, unidirectional flow is considered to be the safest in the associated airflow regime and is the ideal air supply for clean laboratories. On the other hand, due to the lack of bioreactors per hour ventilation20Time requirements, so the biological laboratory does not belong to the cycle of large air volume clean room. And in the biological control of the experimental system, it is not easy to control the wind speed0.1m/sOf the conditions, the humidity, temperature uniform distribution requirements should not be easy to achieve.
In some practice to prove: clean room of the return air is generally set from the ground height of 50-60 cm of the corner position, the air outlet is used diffuser air outlet, this design has a good airflow organization effect.
（二）The design of the differential pressure in the clean room
Reasonable control of the pressure difference in each experimental area can effectively prevent the air in the cleanliness of different laboratory areas between the flow, so that the various regions of the laboratory can meet the requirements of different cleanliness. Reasonable use of the different regional pressure, can effectively prevent the spread of laboratory pollution, the effective prevention of risk factors out of the room, the general negative pressure to be used to run, so not only to ensure biological safety but also to prevent From the outside[1]。
For the biological laboratory pressure differential design of this process is more complex, and also according to different situations to make different design methods, based on past experience, the laboratory pressure is generally maintained at10-30pa, The pressure difference should be controlled by setting the relevant pressure sensor in the area where the pressure difference is formed. The pressure difference between the experimental areas should be ensured by controlling the exhaust and the air supply in the lab.
（三）For the design of air conditioning purification
Generally in order to ensure the indoor air quality in the biological laboratory are generally set up related to the air conditioning and purification system through the role of air conditioning system can also be related to laboratory humidity, temperature and other requirements for adjustment, The air is relatively dry, you can put the appropriate air-conditioning system humidifier or other humidifier to adjust.
Air purification systems generally include three effects: high, medium, and low. The frame structure to be used for the filter is mainly metal, because it is more convenient for disinfection. For the biological laboratory, not only the filtering system should be selected according to the internal exhaust conditions, but also certain equipment should be selected to purify the exhausted air to ensure the safety of the exhausted gas.
二、Composition of control system
Laboratory air purification system consists of two parts, the main include temperature, humidity and pressure control system, air purification system in two parts. Temperature, humidity and pressure control systems include sensors, actuators, and extension units, as well as monolithic microprocessors for measuring data. Air purifying devices include high, medium, and low-pressure filters, and for laboratory discharge Of the gas but also for further treatment, such as ozone disinfection or ultraviolet disinfection, etc.
The monitoring of the entire laboratory system is mainly single-chip microprocessors, which include multi-channel data acquisition circuit、LED、CPUAs well as the related analog-digital conversion circuit and so on several parts. If there is a clogging of the filter device the system will alarm and prompt for replacement[2]。
三、The Principle of Clean Environment Control in Biological Laboratory
In the biology laboratory clean environment control system has set up the related pressure, the temperature sensor, this kind of sensor may be able to transform the collected signal, transforms the data signal into0-10VOf the analog signal. These signals may also be input to the multiplexer circuit for closure of the sensor signal input operation and the tube wall,ADThe conversion circuit inputs the signal to the microcontroller. Adjust the humidity, temperature, and pressure in accordance with the settings for the clean room. But also in accordance with certain requirements on the return air valve and air valve in accordance with a certain proportion of regulation, to maintain a clean room on the fixed30paOf the pressure difference, and can also adjust the temperature and humidity to keep it in the biological laboratory clean environment control system requirements within the scope of.
For the air conditioning unit is concerned, if there is less than the temperature of fresh air5℃Of the situation occurs, the system set up a new internal air temperature sensor can make the heating system to work, the relevant preheater valve open, through the preheater can be fresh air temperature increased to5℃-10℃, If the fresh air temperature is still below the temperature where all of the preheaters have been opened5℃，So that in order to prevent the preheater can be frozen or closed down or reduce the air conditioning unit fresh air valve, until the fresh air temperature preheat return to normal。
If in the summer or in some of the detection of fresh air temperature is higher than the set temperature occurs, the cooling system in this case began to work, the relevant cooling air valve can be mixed to cool the air to meet the biological laboratory process requirements Value.
Laboratory humidity sensor to detect the humidity of the room, in accordance with the requirements of the laboratory process to control the humidifier to maintain laboratory humidity, in the clean room between the relative humidity sensor is mainly used as a humidity monitoring system.
In order to reduce energy consumption as much as possible, for the air conditioning unit of the laboratory selection of the fan is mainly used for frequency units for air, automatic use of the laboratory and the non-probationary period of the use of air volume adjustment to ensure that the experiment room5pa-10paOf the micro-positive pressure, which can effectively reduce energy consumption[3]。
四、Control of biological infection laboratories
In the laboratory of biological infection is mainly harmful virus experimental sites, in such laboratory experiments not only to ensure that the outside air pollution of the laboratory but also to pay attention to laboratory toxic substances for the outside world, so for the entry The laboratory air should be subjected to two-stage filtration, including coarse-medium filtration. For the exclusion of laboratory air, two-stage filtration, including medium and high-efficiency filtration, should be carried out and air disinfection system Auxiliary, must ensure that the exclusion of air from the laboratory can not be infected.
Unlike other laboratories, the main use of the laboratory infection is the DC or new air system, the number of air changes per hour in the10The air flow into the laboratory should be carried out through the exchange of heating or cooling, and then through the two-stage filtration into the laboratory, the air is mainly discharged through the lower part of the exhaust outlet, after filtration and recovery of a certain Of the heat, cold energy after the discharge.
Conclusion：
For the biological clean laboratory control system, there are two forms of control that is clean in the laboratory should be maintained between the positive pressure; the other is the opposite of infection in the room should maintain a negative pressure state, For the laboratory temperature, humidity and pressure control can be controlled using the microcontroller, the use of air conditioning fan operation on the laboratory to adjust the air pressure to protect the laboratory environment is not contaminated, through practice, in the system In the indicators can achieve the relevant technical requirements, but also has many advantages, such as the ability of anti-interference is relatively strong, relatively stable running time, the degree of automation is relatively high for the biological laboratory clean environment control system design Is a very good design。
references：
[1]Feng Qingxiang,Bi and.Design of Clean Environment Control System for Biological Laboratory[J].Applied Energy Technology,2001,06:43-45.
[2]Luo Yaodong.Design of air conditioning system in biological clean laboratory[J].Bulletin of Science and Technology,2008,03:340-343.
[3]Wei Changchun,Chen Guoqiang.Cleaning laboratory and selection of air conditioning and ventilation system[J].Laboratory Science,2013,06:193-197.
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