Precautions for Using High-Voltage Equipment

I. Preliminary Treatment of Disinfectant Items: All instruments, bed linens, clothing, and other items that have come into contact with pathogenic microorganisms shall first be disinfected with chemical disinfectants. Subsequently, perform routine cleaning. In particular, all items used in isolation wards must be rigorously managed: they should be thoroughly disinfected first, followed by washing and further disinfection. During routine cleaning, soak and scrub the items in a detergent solution to remove grease, blood stains, and other contaminants, then rinse thoroughly with running water. Instruments and other items with joints, gear slots, crevices, or similar features should be opened as much as possible or disassembled to allow for thorough brushing and scrubbing. After washing, items should be dried and packaged according to their specific clinical requirements to prevent recontamination. Containers and transport equipment used for contaminated items before and after decontamination must be strictly segregated and clearly labeled to prevent cross-contamination.

II. The packaging and containers for disinfected items must be appropriate; double-layer white cotton cloth should be used for packaging. New cloth should be washed to remove sizing before use. Items should be securely tied with string or twine. The packaging should be snug but not overly tight, to prevent loosening or unraveling. The volume of the package should not exceed that of the sterilization chamber. When using containers for packaging, select those that both effectively block the ingress of external microorganisms and allow good steam penetration, such as specially designed syringe boxes or dressing storage trays. Ordinary household aluminum boxes, however, are unsuitable because steam has difficulty penetrating them and the air inside is hard to vent, often resulting in inadequate sterilization under standard procedures. Comparative tests have shown that their contamination rate is significantly higher than that of medical-grade aluminum boxes; therefore, household aluminum boxes should never be used to package syringes or surgical instruments.

3. Proper loading of disinfection items is essential; overloading or improper placement can both compromise the effectiveness of the process. Items in the sterilization chamber must not be packed too tightly. Do not exceed the pot’s capacity. Whenever possible, place similar items in the same pot. If different types of items are placed together, prioritize the temperature and time required by the item that is most difficult to bring to the desired conditions. When loading items, arrange them in a staggered pattern—alternating top and bottom, left and right—to create gaps that allow steam to penetrate easily. Large sterilization packs should be placed upright on the upper rack, while smaller packs go on the lower rack. Large enamel boxes and storage tanks should also be positioned vertically. When sterilizing cloth and metal items simultaneously, place the metal items on the lower rack so that both receive roughly the same heat exposure, and to prevent condensation from the metal items from wetting the wrapping cloth.

IV. When using a high-pressure steam sterilizer, ensure that all air is completely expelled. The key is to completely remove the air from the autoclave. If air remains in the chamber, the pressure indicated by the pressure gauge will not correspond to the saturation vapor pressure. At a given pressure, steam containing air will have a lower temperature than saturated steam. As shown in the table, the relationship between pressure and temperature varies depending on the degree of air removal: when all air is removed, the temperature is °C; when some air remains, the temperature is lower—equivalent to boiling. However, this temperature is insufficient to kill spores or hepatitis viruses within a short period, thereby compromising sterilization efficacy. Therefore, thorough venting is essential, and the venting time should be approximately minutes.

V. Rational Calculation of Time Time includes: ① penetration time, which is the duration from the moment the temperature inside the vessel begins to rise until even the most difficult-to-heat areas within the vessel reach that temperature; ② holding time, which is the time required to inactivate microorganisms. It is generally expressed in terms of the time required to kill the spores of Geobacillus stearothermophilus; during sterilization, these spores are killed within a certain number of minutes. The “safety margin” refers to the additional time that must be added to ensure absolute certainty of sterility. This safety margin is typically half the thermal death time and its duration depends on the nature of the items being sterilized. For metal instruments that conduct heat readily, no safety margin is required. During the sterilization cycle, it is essential to monitor the pressure gauge and adjust the steam inlet flow rate to maintain the specified pressure throughout the entire cycle. If, during the process, either the pressure or temperature drops, the chamber must be reheated and repressurized, and the timer reset to resume the cycle.

VI. It is required that disinfected items be allowed to dry, Once the indicator has reached the required level, the sterilization process may be terminated. When handling sterile items, strict aseptic techniques must be followed: immediately replace the lid on any opened container and securely close the vent holes of storage tanks. Items should be stored at least one foot above the floor, at least one foot from the ceiling, and away from walls to minimize contamination from the floor, ceiling, and walls. In addition, items should be sorted and arranged in an orderly manner for dispensing and retrieval. For items with a limited shelf life, the maximum storage period is generally no more than seven days during hot, humid seasons; during cold, dry seasons, this period may be extended to ten days. Any items exceeding their expiration date or storage time limit must be discontinued from distribution.

VII. Prevention of Superheated Steam: For example, under pressure, steam should be maintained at a specific temperature; if the temperature exceeds this limit, it becomes superheated. Although superheated steam has a high temperature, like air it cannot condense into water when it comes into contact with sterilized items and therefore cannot release latent heat, which is detrimental. To prevent superheating, when using an external-steam sterilizer, ensure that the temperature in the jacket does not exceed the temperature in the sterilization chamber; the two temperatures should be closely matched. Avoid introducing steam at excessively high pressure into the sterilization chamber, do not allow moisture-absorbing items to become overly dry before sterilization, and do not use high-pressure steam to heat the chamber to the required temperature and then immediately reduce the pressure.

VIII. Safety Precautions: Before each use, verify that the sterilizer is in good working condition, with particular attention to the proper functioning of the safety valve. After sterilization, reduce the pressure gradually and avoid abrupt or excessive depressurization. Only open the chamber door when the pressure gauge has returned to zero. If the sterilizer contains bottled solutions and the door is opened suddenly, the glass may shatter upon sudden exposure to cold air. Additionally, opening the door too wide and allowing a large influx of cold air can cause steam surrounding the wrapping material to condense into water droplets, clogging the pores of the wrapping and impeding the escape of steam from within, thereby leading to dampness of the items being sterilized.