2.2 The panel thickness is generally 100 mm, with plastic-coated color-steel sheet on both sides; the color-steel surface is formed with concealed grooves. The panels are lightweight, high-strength, and have good thermal insulation, corrosion resistance, and aging resistance; they are simple and quick to assemble, making them one of the best material choices for the insulated envelope of cold rooms.

　　2.3 The panel core is integrally foamed from lightweight polyurethane with excellent thermal insulation (consistent with the inner core material of freezers); its thermal insulation performance is particularly good.

　　2.4 The double-faced color-steel panels use advanced eccentric hooks and groove hooks; the eccentric connection achieves tight joints between panels, and the excellent sealing minimizes cold air leakage and enhances the thermal insulation effect. Cold rooms assembled from T-panels, wall panels, and corner panels can be erected in any space—simple, practical, energy-saving, and environmentally friendly.

3. Electrical Control Section

　　3.1 The electrical control box outside the cold room has an automatic dual-circuit switching function, usually referring to the normal power supply and the backup power supply.

　　3.2 It can control the automatic switchover between the main and auxiliary compressors, digitally displays the room temperature, and has automatic monitoring, regulation, display, and upper/lower temperature limit alarm functions. Temperature recording uses the most advanced temperature recorders.

4. Refrigeration Section

　　4.1 A backup refrigeration unit is provided: two 3P compressors are installed and used alternately.

　　4.2 Cold room refrigeration equipment—mainly the selection of the cold room compressor and evaporator. In general, small cold rooms mainly use fully hermetic fluorine refrigeration compressors. Because fully hermetic compressors have low power and are relatively inexpensive, and the equipment runs smoothly with low energy consumption and a low failure rate, they are currently the preferred units for cold rooms.

　　For the preservation of vaccines, pharmaceuticals, etc., suitable for hospitals, universities, and research institutions, these are dedicated constant-temperature devices for storing and displaying biological sample products, and can be used for scientific research and teaching demonstrations.

VI. Cold Room Selection and Purchase

1. Selection of the Evaporator Inside the Cold Room

　　There are two types: pipe coils and ceiling-mounted air coolers. In general, high-temperature (chiller) cold rooms use air coolers as evaporators, characterized by fast cooling but liable to cause moisture loss in refrigerated goods; medium- and low-temperature cold rooms mainly use evaporator coils made of seamless steel pipe, characterized by good temperature stability and the ability to store cold in a timely manner.

2. Selection of the Refrigeration Unit

　　A refrigeration compressor assembled with accessories such as a condenser is called a refrigeration unit; refrigeration units are water-cooled or air-cooled. Small cold rooms mainly use air-cooled units. The compressor of the refrigeration unit is the heart of the cold room; common compressors are of domestic or imported semi-hermetic and fully hermetic types.

Section 8 Medical Laboratory Disinfection and Sterilization System

　　Because the laboratory comes into contact with large numbers of specimens every day—including blood, urine, feces, sputum, pleural and peritoneal fluid,

puncture fluid, bile, etc.—in medical laboratory work, proper disinfection and personal protection, and handling specimens according to rational procedures, are the basic measures for effectively controlling nosocomial (hospital-acquired) infection.

I. Division of Medical Laboratory Zones and Disinfection Content

　　Zoning: by contamination status, the laboratory can be divided into clean zone, semi-contaminated zone, and contaminated zone.

　　Disinfection targets: e.g., disinfection of contaminated test requisition forms, air disinfection, disinfection of testing equipment, hand disinfection, disinfection of discarded specimens, and disinfection of general environmental surfaces indoors.

II. Disinfection Methods and Measures

　　1. Disinfection of contaminated test requisition forms: use a high-intensity UV sterilizer, moving it slowly at no more than 3.0 cm above the plane of the form, irradiating for 3–5 seconds on both sides. Formaldehyde sterilizer fumigation may also be used, with a fumigation time of more than 2 hours.

　　2. Air disinfection: air disinfection by ultraviolet lamp irradiation is generally used in all laboratory areas; ozone generator disinfection (ozone generators are now less commonly used by hospitals). Operations that generate infectious aerosols in the contaminated zone—especially operations involving diseases transmissible via the respiratory tract—shall be carried out in a biosafety cabinet, so that the air is discharged outdoors through a bacterial filter or a thermal sterilization channel; this minimizes contamination.

　　3. Disinfection of various surfaces in the contaminated zone. Disinfection of surfaces such as tables and chairs: wipe once with a wet cloth before starting work each day; mop the floor once with a wet mop; dry wiping and dry sweeping are prohibited. Cloths and mops shall be dedicated to each room and must not be mixed. Before leaving work, wipe once with 250–500 mg/L available chlorine or 0.1%–0.2% peracetic acid. Floor disinfection: mop with the above disinfectant at double concentration.

　　4. Single-use plastic products: e.g., disposable syringes shall be destroyed and disinfected after use. Film gloves shall be placed in medical waste bags after use for centralized harmless disposal. Careless disposal after use creates secondary contamination and fails to protect individuals.

　　5. Personnel disinfection: laboratory personnel required to go to wards to draw blood must dress neatly and wear masks and gloves. Blood collection must strictly follow "one person, one needle, one tourniquet." When personnel need to drink water, use the toilet, or do other things during work, and when leaving work, they must wash their hands strictly; when staff skin or clothing is contaminated with specimens or dirt, strict disinfection and washing must be carried out.

　　6. Instrument disinfection: all instruments used in testing operations that require disinfection must be disinfected by category in strict accordance with disinfection procedures, ensuring no cross-contamination during experiments, so as not to affect test results or cause cross-contamination among laboratory staff.

　　7. Discarded specimens: for discarded specimens such as urine, pleural fluid, ascitic fluid, cerebrospinal fluid, gastric fluid, and joint cavity fluid, add 5 g of bleaching powder per 100 ml, mix well, let act for 2–4 hours, then pour into the medical waste collection bin. Sputum, pus, blood, feces, and other solid specimens shall be incinerated or mixed with twice the amount of bleaching powder, allowed to act for 2–4 hours—for hepatitis and tuberculosis specimens, extend to 6 hours—then poured into the medical waste collection bin.

  1. Waste and wastewater treatment: all laboratory waste must be managed in accordance with the Regulations on the Management of Medical Waste and the Measures for the Management of Waste from Medical and Health Institutions, with detailed registration by a designated person. All laboratory waste liquid must be disinfected first and must be treated at the hospital's dedicated sewage treatment station before being discharged into the municipal network, to prevent pathogens from spreading through sewage and causing harm to society.

III. Sterilization Equipment

1. Ultraviolet Lamps

　　A UV lamp is an artificially made low-pressure mercury quartz lamp: mercury is sealed in a quartz glass tube, and when energized the mercury vaporizes and emits ultraviolet light. Sterilization and disinfection are carried out through the UV lamp tube. UV germicidal efficacy is closely related to wavelength: the strongest germicidal capacity is at 250–260 nm, and 250 nm is generally taken as the representative germicidal wavelength. Domestic UV tubes come in 15 W, 20 W, and 30 W versions, all with a wavelength of 250 nm. They are mostly used for disinfection of air and object surfaces.

1.1 Method of Use

　　1.1.1 Installation of UV lamps for sterilization: UV tubes irradiate via suspended or mobile lamp stands. When suspended indoor UV disinfection is used, the number of UV disinfection lamps installed indoors (30 W UV lamps, intensity > 70 μW/cm² at 1.0 m) shall average no less than 1.5 W per cubic meter, with an irradiation time of no less than 30 minutes.

　　1.1.2 When used for air disinfection, doors and windows shall be closed; each disinfection session shall be no less than 60 minutes, timed from 5–7 minutes after the lamp lights up; personnel are prohibited from entering the room during irradiation, and if entry is required for work, irradiation shall be stopped.

　　1.1.3 When disinfecting items, spread them out or hang them up to enlarge the irradiated surface; the effective distance is one meter, with irradiation of no less than 30 minutes.

　　1.1.4 The environment in which UV is used shall be kept clean, and the air should be free of dust and water mist; when the indoor temperature is below 20°C or the relative humidity exceeds 50%, the irradiation time shall be extended. Never perform UV disinfection immediately after mopping the floor; it is recommended to wait until the floor is dry before UV lamp disinfection. In water treatment rooms with high humidity, in addition to extending the irradiation time, staff should enter only half an hour after irradiation is complete, or use automatic UV irradiation at night.

　　1.1.5 The surface of UV tubes shall be kept clean and dust-free; wipe once a week with a 95% ethanol cotton ball and record it.

　　1.1.6 UV light causes certain damage to human skin and mucous membranes; take protective measures and never look directly at the UV light source with the eyes.

　　1.1.7 Each lamp tube shall have a usage time logbook, with one record per irradiation; the service life is 1,000 hours, or test once every six months with a UV intensity indicator card and paste the result in the logbook. Note

that UV intensity indicator cards have a relatively short validity period—buy few and buy often (note: new tubes must test no lower than 90 μW/cm², and tubes in use no lower than 70 μW/cm²). When a UV tube still tests no lower than 70 μW/cm² after 1,000 hours of use, it shall be tested every 30 hours; when the irradiation intensity falls below 70 μW/cm², it shall be replaced.

2. Autoclave (High-Pressure Steam Sterilizer)

　　The autoclave, also called a high-pressure steam sterilizer, can be divided into portable sterilizers and vertical autoclaves. It is a device that uses electric heating elements to heat water to produce steam and maintain a certain pressure.

　　It is suitable for the medical and health industry, especially hospital clinical laboratories, for disinfecting and sterilizing medical instruments, dressings, and glassware—it is ideal sterilization equipment.

　　As one of the indispensable devices in the laboratory, the autoclave plays an irreplaceable role in sterilizing culture media. In addition, in waste treatment, all waste containing pathogenic microorganisms must be sterilized before it can be treated as ordinary waste. In particular, splashes or leaks that may occur during operations must be efficiently disinfected, so as to kill pathogenic microorganisms and protect operating personnel. The high-pressure steam sterilizer is currently one of the most widely used and most effective sterilization devices.

　　The principle of high-pressure steam sterilization is that water boils at about 100°C at normal atmospheric pressure, and as steam pressure increases, the boiling temperature rises accordingly. Therefore, in a sealed autoclave, when the pressure gauge indicates that the steam pressure has increased to 15 psi (1.05 kg/cm²), the temperature is equivalent to 121.3°C; at this temperature, 20 minutes can completely kill bacterial vegetative forms and spores.

　　Medical laboratories mainly use autoclaves in microbiology, HIV laboratories, gene sequencing laboratories, washing and disinfection rooms, etc. Vertical autoclaves are commonly used in laboratories.

3. Ozone Disinfection

　　In medical environments, to effectively control microorganisms in aseptic production clean zones, appropriate disinfectants and sterilants must be selected to kill bacteria in the air of the clean environment and floating on the surfaces of machinery, molds, containers, and building structures, so as to maintain the cleanliness environment required for the production of "sterile pharmaceuticals."

　　If the requirements for disinfection effectiveness are not strict, a wall-mounted or mobile ozone sterilizer is recommended; if a central air-conditioning system is present, an air-conditioning-type ozone sterilizer is recommended first, but preferably one that can be installed externally; if there is no central air conditioning or it is inconvenient to use, a duct-type ozone sterilizer is recommended—in addition to guaranteeing the disinfection effect, if central air-conditioning disinfection is needed later, there is no need to purchase another ozone sterilizer.

3.1 Advantages of Ozone Disinfection and Sterilization

3.1.1 No dead corners—ozone permeates everywhere. Ultraviolet light only has a germicidal effect when it reaches the surface of an object at a certain irradiation intensity; UV irradiation intensity is far from sufficient, especially at a distance, and irradiation produces large dead corners. Ozone is a gas with strong permeability, good diffusivity, and uniform concentration, with no dead corners.