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Clean Room Design and Construction

Hospital medical industry is a very large and special industry, especially the hospital operating room has a high requirement for air cleanliness. Generally, qualified hospital operating room or medical clean room requires a minimum of 30% efficiency prefilter and 90% efficiency sub high efficiency filter to filter the hospital air. In general, high efficiency filter is not required, but in special cases, such as isolation room, specific testing and nursing area, high efficiency filter is required.


Clean operating room category and grade reference:


Hospital operating room name                       category               cleanliness


Special sterile clean operating room                      I                     class 100

Sterile operating room                                           Ⅱ                    class 1,000-10,000

General operating room                                        Ⅲ                    class 10,0000

Bacterial operating room                                       Ⅳ                    >= class 10,0000

Toxic operating room                                              V                    no requirements

Operation auxiliary area                                         Ⅲ                   class 100,000

Other rooms                                                                                   class 100,000-100,0000


The clean room of the hospital system was first applied in the operating room, which is what we now call the hospital operating clean room project. At first, it was only widely applied in orthopedic surgery, because orthopedic surgery took a long time and was easy to cause infection. The ideal control level is to use the air cleanliness near the operating table to reach level 100. It is generally recommended to use the top high efficiency air filtration system, which can cover an area of at least 3M × 3M, so as to include the operating table and people.


Other medical clean room application include delivery room, nursing room, burn room, heart patient care unit, etc. One of the latest developments is the clean room application in dental surgery, which reduces the risk of infection of medical staff during long-term operation.


As one of the important functional divisions of the hospital, the engineering quality of clean room directly affects the use of the hospital and the treatment of patients. To improve the engineering quality of hospital clean room, we must pay attention to the design, construction and maintenance at the same time.


The clean room application in the hospital is a modern operating room which uses air cleaning technology to replace the traditional ultraviolet ray and other means to control the pollution in the whole process. In a clean operating room, the infection rate of patients can be reduced by more than 10 times, so that antibiotics that will damage the immune system of patients can be used less or not. It is the characteristic of clean operating room to be dust-free and sterile.


Hospital clean room includes operating room, obstetrics, infant ward (NICU), ICU (intensive care unit), burn ward and dissection room, purification laboratory, artificial dialysis room, specimen room, etc. its engineering quality has a direct and important relationship with medical quality.


1、 Clean room design


Code for clean room design and construction and acceptance (hereinafter referred to as "code") emphasizes that fresh air must follow the principle of three-level filtration. This is because compared with the air conditioning system, the dust concentration load ratio of the fresh air of the purification system is more than 90%. Therefore, in order to operate quality, it is necessary to emphasize the three-stage filtration of the fresh air. Now the standards and specifications of hospital clean operation department have taken this as a regulation. In addition, the return air must have a filter, which can discharge the medium efficiency best. Only when the designer understands the requirements of "standard" accurately, can the clean room meet the functional requirements of the hospital to the greatest extent.


In order to ensure the quality of the clean room project, the designer must carefully investigate and inspect the construction site of the hospital clean room, otherwise, the quality of the designed clean room project will be greatly reduced. For example, when testing the dust concentration in the clean room of a hospital, it is suddenly found that the dust concentration generally rises sharply and exceeds the standard seriously. The first thing that engineers thought about was the leakage at the air outlet of the filter. After inspection, although it was found that there was leakage, it was not the same as the amount of dust concentration detected. According to experience, this is the improper design of the new air outlet. Because the new air outlet is located on the top of the 5-story building and downward, there is a garbage station just below it. The garbage station has the habit of burning garbage regularly. A large amount of dense dust is just the smoke from the bottom of the new air outlet. The location of such a new air outlet will inevitably result in the result of endangering the indoor cleanliness. Regardless of the later construction quality, the engineering quality of the clean room is also difficult to meet the requirements. In fact, this is in violation of the general requirements of the "code" that the new clean operating room should be far away from the pollution source.


Clean room design is the foundation of clean room quality, clean room design is the first guarantee of clean room engineering quality.


2、 Clean room construction


Clean room construction quality control can be divided into three stages: preparation stage, construction stage and acceptance stage.


  • Key points of quality control in preparation stage


1. Carefully conduct joint review of drawings and technical disclosure


Fully understand the design intent, do a good job in drawing review and technical disclosure is an important technical link to ensure the quality of the clean room construction, find and solve technical problems that are difficult to operate in the clean room construction, and lay a solid foundation for ensuring the clean room construction quality.


There will be various contradictions in the clean room construction, which requires the cooperation of the construction party, the design party and the construction party to make reasonable changes on the premise of ensuring the clean room construction quality.


If it is found in the inspection of a clean room reconstruction and expansion project that the size of the original designed air duct cannot be constructed in the ceiling layer of the main building where the floor height is limited, the construction company and the The coordination between the designer and the builder, on the premise of not affecting the quality of the project, changes the size of the air duct from square to flat, which not only meets the requirements of the air volume, but also ensures the requirements of the ceiling height.


2. Strictly control the quality of materials and equipment


The materials and equipment of clean room mainly include all kinds of decoration materials and air conditioning equipment materials. The decorative materials shall be inspected and verified in strict accordance with the requirements of relevant national engineering technical standards, construction quality acceptance specifications and design documents. The clean room shall be made of materials that are dust-free, corrosion-resistant, moisture-proof, easy to clean and have fire-proof function. Wood and gypsum board shall not be used as surface decoration materials.


The air conditioning insulation materials must also meet the requirements of corrosion resistance, no dust generation, no dust adhesion and fire protection in accordance with the relevant national regulations.


  • Key points of project quality control


1. Select professional trained construction team


Clean room construction involves decoration, HVAC, electrical, medical gas and other disciplines. Construction personnel must have a comprehensive understanding of clean room construction specifications, construction technology and construction quality, otherwise, construction quality is difficult to be guaranteed.


2. Key points of sealing control in clean room


The key content of the clean room sealing control is the sealing construction quality of the enclosure. For example, the sealant should be evenly applied between the plate and the plate to ensure that there is no air leakage; The socket, switch, smoke detector, lighting box, medical lamp belt and film viewing lamp installed between the wall mounted instrument cabinet and the wall in the clean room shall be sealed with sealant, and reliable and effective sealing measures shall be adopted between various pipes and boxes in the instrument cabinet.


3. Quality control of air supply and return pipes


The sealing of the air supply and return system pipeline is to prevent the unclean air from entering the air duct, prevent the polluted air in the air duct from permeating out, so as to meet the cleanliness of the clean room and extend the service time of the high efficiency filter. During the construction, the quality of pipeline processing, pipeline construction and equipment installation shall be mainly controlled.

The cleaning of air pipe equipment and sealing measures in the process of pipe processing shall be emphasized. The pipeline shall be made of high-quality galvanized steel plate to meet the requirements of flatness, smoothness, firmness and corrosion resistance; the silencing materials filled in the muffler shall be free of dust, slag (fiber), moisture absorption and pollution, and shall not be loose materials. The fiber materials shall be felt materials, and the outer covering shall be the packaging materials that can prevent fiber penetration. Foam plastics and centrifugal glass wool should not be used. Before the air duct is manufactured, the neutral detergent shall be used to remove the oil stain, and the scratch shall be prevented during the manufacturing process. At the end of manufacturing, the white silk cloth shall be used to wipe the inner surface without any oil stain and ash mark, which is qualified for cleaning. After the air duct section is processed and cleaned to be qualified, both ends of the air duct shall be protected with plastic film and then transported to the site for installation. All air duct accessories and equipment shall be wiped clean before installation, otherwise they cannot be installed.


In the process of pipeline connection and equipment installation, sealing measures shall be taken to avoid secondary pollution. Due to dust retention problems of hose and soft joint, soft joint can be used when connecting purification pipeline and mechanical equipment, but it is not suitable to be used on pipeline.


Secondly, it is more meaningful and easier to be ignored to control the secondary microbial pollution than the secondary pollution. The secondary microbial pollution is contained in the secondary dust pollution, mainly in the air conditioning treatment unit. During the shutdown period, the environment with high temperature and humidity and the nutrition provided by the dust provide the most favorable conditions for the propagation of microorganisms. The newly propagated microorganisms and the harmful odorous gases and a large number of harmful metabolites, corpses and fragments released by them - a large part of which cannot be blocked by high efficiency filters, thus constituting the secondary pollution of microorganisms.


Facts tell us that soft joint is also an important source of microbial secondary pollution. This is because soft joints are usually not insulated and condensation occurs here. For medical cleanrooms, even a small number of soft joints must be double-layer or insulation soft joints.


Finally, all joints of the combined air conditioning unit shall be sealed, and water seal shall be set on the condensate drain pipe of the surface cooler to ensure that the air conditioner is sealed without air leakage.


  • Key points of quality control in acceptance stage


The commissioning of the purification air conditioning system is an important work in the project acceptance stage. Through debugging, some defects in construction can be found in time and rectified and repaired in time. Debugging is also an important verification process for design drawings.


The air supply and return pipes of clean room and air conditioner shall meet the cleaning requirements before the installation of high efficiency filter. The purification air conditioning system must be continuously air blown for more than 12 hours. After air blowing, the air supply and return pipes and the interior of air conditioning unit shall be cleaned and scrubbed.


After the completion of the project, the construction unit shall organize the medical department, the corresponding departments using the clean room, the clean room design and construction unit to carry out the construction quality acceptance of the clean room in accordance with the engineering design documents, the technical code for construction of clean operating Department of hospital, the code for construction acceptance of ventilation and air conditioning engineering, the code for construction and acceptance of clean room, etc. The room shall be subject to strict quality acceptance, and a qualified third-party testing unit shall be entrusted to test the cleanliness of the clean room against the design documents and relevant standards and specifications.


3. Clean room maintenance


It also plays an important role in the process of ensuring the quality of hospital operating room purification engineering. According to the data, the staff in the clean room of a hospital suddenly fainted. On the one hand, the fresh air heater was not effectively filtered, and the relevant parts on the pipeline were seriously blocked. Due to the lack of maintenance, there was no fresh air intake. In addition, some fans in the air conditioning box were dropped, and the total air volume was small, which led to the relatively closed clean room. The weak people were in the room with long-term hypoxia fainting will occur within.


For example, a clean operating room in a hospital suddenly found a large increase in bacterial concentration at a certain point on a certain day, only to stop the operation for investigation. As a result, a visible hole was found in the filter above a certain point. Technicians believe that this loophole has existed before. The problem is that there is no inspection and leakage detection system for the filter at ordinary times. If the orifice plate is often opened for inspection, this problem is not hard to find.


Through the above discussion, we can see that clean room design, construction and maintenance are the three factors to ensure the quality of hospital clean room project. Only when we ensure the functional rationality of the clean room drawings in the design, strictly follow the drawings in the construction to ensure the quality process control of the clean room, and pay attention to regular inspection and maintenance of the clean room project at ordinary times, can we guarantee the project quality of the clean room from the Perspective of overall quality control.

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