The sterilization of clean rooms in biopharmaceutical cleanrooms and other cleanliness industries has the disadvantages of long time, poor verifiability, and destructiveness. Through the combination of VHP space sterilization technology and air conditioning systems in biopharmaceutical cleanrooms, and through typical engineering examples analysis, the VHP is explained how to use the air conditioning system for system dehumidification, material selection, air conditioning system cooperation, envelope structure and safety. Space sterilizing applications. This sterilization method can be used to refer to similar clean room sterilization fields.
The common sterilization methods in clean rooms are difficult to standardize, labor-intensive, difficult to verify, and potentially dangerous to operators and the environment. The VHP sterilization technology combined with the air conditioning system, in addition to being able to overcome the shortcomings of the traditional sterilization technology, also has the following advantages: excellent material compatibility, broad-spectrum bactericidal efficacy, reproducible, higher level of sterility assurance. Therefore, research on how the VHP is combined with the air conditioning system for space sterilization has important practical significance for large-scale, standardized space sterilization of biopharmaceutical clean rooms in the future.
1VHP sterilization
VHP (Vaporized Hydrogen Peroxide) is vaporized hydrogen peroxide. In recent years, studies on the sterilization effect of gaseous hydrogen peroxide have been reported. Its main principle is to generate free hydroxyl groups for attacking cellular components, including lipids. , Protein and DNA, and has been widely used in the sterilization of the biopharmaceutical industry [1-2].
The comparison between VHP sterilization and traditional sterilization methods has been studied [3-4]. From various comparisons, the VHP sterilization method has no effect from sterilization, residue after sterilization, sterilization time, and applicable occasions. And in the actual sterilization process to the operators of the harm, compared to the traditional sterilization method has its obvious advantages.
2VHP Space Sterilization Project Implementation
In 2015, the Turkish V project undertaken by our company invested in the establishment of an animal vaccine manufacturing workshop in Ankara. The raw material used in the production process was highly resistant to animal vaccines. In clean rooms such as animal hatchery, medicine filling workshops and animal laboratories in the production area, raw materials and intermediates enter and leave the production area during the production process. This requires efficient and reliable sterilization methods for the surface and The space is sterilized while the material transfer needs to be completed with the minimum operating time. For the characteristics of this project, it is necessary to find suitable sterilization methods in various sterilization processes.
In the process of considering various comprehensive solutions, several requirements are put forward for the user. First, the sterilization frequency is high, which requires the shortest operating cycle; second, the dry sterilization method should be adopted to reduce the sterilization cycle. Impact on the overall controlled environment of the cleanroom.
Based on past domestic project experience and understanding of the EU GMP, and considering the actual operation of the project and the remote technical communication and remote equipment materials transportation, the project finally selected a fixed VHP generator for the clean space system. The method of sterilization is more suitable for the requirements of this project.
Application of VHP for System Space Sterilization
(1) The Turkish V project uses a fixed VHP combined with an air conditioning system to sterilize the room. As shown in Figure 1, Figure 2.
(2) VHP sterilization process
Dehumidification - Reduce the relative humidity in the space to the desired humidity level for the desired VHP sterilization.
Keep the valve of the VHP generator device connected to the air duct system closed, the system is operated by the air conditioning unit, and the humidity is minimized through the dehumidification function of the runner so that the air in the air conditioning system and the room can reach the cleanliness level and temperature and humidity required by the clean system. You can. That is, VHP sterilizes best when sterilized at low humidity (humidity < 40%).
Adjustments—Increase the injection rate, reduce the cycle time, and rapidly increase the H2O2 concentration.
Close the new air valve and exhaust valve of the air-conditioning system, close the cold and heat source valves of the air-conditioning system, open the dry air control valve to the room to the fully open position, and open the VHP pipe and the valve connected to the air-conditioning system to the fully open position. The VHP generator is turned on, and the hydrogen peroxide adding device supplies liquid hydrogen peroxide to the VHP generating device, and the hydrogen peroxide gas generating device converts liquid hydrogen peroxide into gaseous state, and then passes through the air supply branch pipe (see FIG. 3) and the air supply port. Transfer to the clean room that needs to be sterilized, and sterilize rooms, materials, products and equipment. While the VHP and the dry air enter the closed clean room, the exhaust valve is adjusted by the automatic control system according to the amount of gas passed. The relative humidity of the entire air-conditioning system during this adjustment is approximately 50%.
Biological decontamination - maintain a certain concentration of H2O2, with a constant "sterilization" capability.
The air-conditioning system maintains a certain VHP concentration in the air ducts, rooms, and equipment to achieve sterilization. This project sets the concentration of 607mg/m3.
Ventilation - Contains circulation, rapidly reducing the concentration of H2O2 for health and safety purposes.
After the sterilization is completed, close the valve on the VHP pipe connected to the air-conditioning system, and turn on the fresh air and exhaust valve of the air-conditioning system, close the valve that enters the room's dry air, and decompose the excess hydrogen peroxide gas through the catalytic cracker. After the emission standards are removed by the exhaust system.
Application of Fixed VHP Space Sterilization in Practical Projects
(1) The problem of humidity during sterilization
Since mobile VHP generators are generally equipped with a dehumidification device, it is possible to ensure that the humidity in the space during sterilization can be controlled at 40%, and the VHP sterilization effect is best at this humidity. However, in the Turkish V project, a fixed VHP sterilization system was used. This project minimizes system humidity by using a combination of an air conditioning unit with dehumidification and a separate dry air system.
In order to ensure the best sterilization of the room in this project, the sterilization space has reached the following conditions before sterilization:
1 Room temperature ≥25°C, humidity ≤40%.
2 The number of air changes in the room is ≥10.
3 The hot and cold water valve is controlled automatically by BMS, and the exhaust fan is controlled by frequency conversion.
4 Ensure that all doors and openings in the sterilization space are closed.
5 The humidity control before sterilization is achieved by changing the frequency of the blower and exhaust fan and the dehumidifier on the runner.
(2) HEPA filter problems during sterilization
Generally speaking, biopharmaceuticals have high efficiency filters at the end of each clean room. If the VHP needs to pass through a high efficiency filter, the speed of killing microorganisms will be slowed down due to the absorption of the filter medium, and the final stage of ventilation time will be reduced. The increase leads to an extension of the entire sterilization cycle. The high efficiency filter in the project system is set in the air conditioning unit, so this problem does not exist. However, in practical applications, it is unavoidable to place a high-efficiency filter at the end of the air duct. It is advisable to bypass the high-efficiency filter to speed up the sterilization of the work area. Of course, VHP is also compatible with high-efficiency filters. High-efficiency filters made of aluminum frames and glass fiber media can be used to ensure that silicone is used for sealing.
(3) The application of airtight enclosure in VHP sterilization system
The VHP sterilized clean room containment structure in the Turkish V project uses a 50mm thick sandwich metal partition series color steel plate. The problem of clean room sealing during VHP sterilization is also one of the key difficulties in construction control. The construction sequence of the envelope structure of this project shall be carried out in the order of top plate and then wall plate, which is more conducive to the seal between the top plate and the wall plate. All the gaps are sealed with porcelain white neutral gel and double-sided sealant. Can not be double-sided sealant seams, such as relying on the construction of the wallboard, wrapping column wallboard, sandwich channel wall plate, etc. according to the principle of positive pressure seal, the installation should be in the plate joints before the injection of sealant, using four points in the tank The use of glue or diagonal glue to fill gaps between the connection fittings and the plates ensures that no leakage occurs.
(4) Application of Inflatable Sealing Door in VHP Sterilization System
Inflatable airtight doors are mainly used in the inlet and outlet buffers of VHP sterilization space. In the clean room, the room maintained by the color steel plate is usually considered to be closed. Only the gates for entering and exiting personnel and materials need to use sealed and reliable airtight sealed doors as the dedicated gate for the airlock to ensure the sterilization process. In the sterilization environment, it is completely isolated from the external environment.
Inflatable sealing door mainly has three major functional modules: one is the inflatable sealing structure of the door, the second is the interlocking control system, and the third is the clean compressed air charging and discharging pipeline system. The inflatable airtight door is mainly composed of a door frame, a door panel, an inflatable sealant, a charge-and-discharge control system, and a logic control system with related components. The inflatable seal is embedded in the groove of the door panel skeleton. The four corners of the door frame and the door panel are arc angles of R>150 mm, the door panel is a sandwich structure, and the middle is a heat-insulating and heat-insulating material, and both side panels are firmly combined with the skeleton through the press-bonded system board technology. The door frame and door are made of 304 stainless steel. As shown in Figure 4.
The working principle of the inflatable airtight door is: when the door is opened, the inflation expansion sealing strip is deflated and contracted in the groove; when the door is closed, the inflation sealing strip is inflated so as to form a tight seal between the door and the door frame, and the door is closed. Electromagnetic lock locked. The key verification points for inflatable seal doors are airtight reliability and the safety of control logic. This was fully verified during the implementation of the Turkey V project. Before leaving the factory, each customer leaves the factory to carry out FAT, and to ensure that one by one through the leak test can be shipped. VHP sterilization technology and inflatable sealing door technology are inseparable in the application of VHP.
(5) Material application of VHP sterilization integrated air conditioning system
1 piping system
• VHP pipe: CPVC material recommended
• Wind system piping: The duct is made of galvanized steel. Acceptable is the duct. The duct of Turkish V project is made of galvanized steel with a galvanized layer thickness of 180 g. It is not used in later commissioning verification. There is a problem; the humidity probe in the pipeline is not in the form of a copper coil.
2 Enclosure structure
Fluorocarbon-coated colored steel plates were used in VHP-sterilized rooms, and conventional PE-coated color plates were used in non-VHP-sterilized areas. Doors for clean rooms that require VHP for sterilization are recommended to use melamine resin doors, and each independent sterilizing space uses airtight doors for doors connected to other systems. Regardless of the construction material used, the room must be well sealed during sterilization to prevent work exposure to adjacent work areas.
Conclusion
Through the above VHP's application of the space sterilization technology in the project, it can be seen that the VHP sterilization technology can be used in combination with the air conditioning system like the ozone disinfection method, but it needs to pay special attention to the system humidity and airtightness in the process, and pay attention to relevant The choice of material. The entire process of VHP sterilization is verifiable, reproducible, and compatible with conventional biopharmaceutical cleanrooms, production process equipment, and electronics for record monitoring. This sterilization process is rapid [5 ]. Therefore, the VHP technology proposed in this paper can be used to sterilize the air conditioning system and can be used as a reference to the similar clean room sterilization field.
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