Autoclave is a device that uses high-temperature saturated steam under high pressure to sterilize items. Invented by French scientist Charles Chamberland in 1879, it is renowned for its efficiency and reliability, and is regarded as the most critical "safety guardian" in the fields of microbiology, medicine, and pharmaceuticals.
1. Working Principle
The working principle of an autoclave is based on a basic physical fact: as pressure increases, the boiling point of water also rises.
In a sealed chamber, high-pressure saturated steam is generated by heating. When the pressure rises to approximately 0.1–0.2 MPa, the steam temperature reaches 121°C–134°C. When this high-temperature saturated steam comes into contact with cooler items to be sterilized, it rapidly condenses and releases a large amount of latent heat, instantly raising the temperature of the items. This causes irreversible denaturation and coagulation of microbial proteins and nucleic acids, achieving the effect of killing all microorganisms, including bacterial spores.
A standard autoclave cycle typically includes the following stages:
·Exhaust Stage: Cold air inside the chamber is removed using steam or a vacuum pump. This is the most critical step. If air remains, it will affect steam penetration and lead to sterilization failure.
·Heating/Exposure Stage: After the air is completely removed, the exhaust valve is closed, and heating continues until the preset sterilization temperature (e.g., 121°C) is reached. This temperature and the corresponding pressure are maintained for a period of time (typically 15–30 minutes).
·Exhaust/Cooling Stage: After the sterilization time is completed, heating is stopped, and steam is slowly exhausted to reduce the pressure to zero. The items are then dried using residual heat or a vacuum system.
2. Classification
Autoclaves can be classified based on structure, volume, and functional principles:
|
Classification Dimension |
Main Type |
Characteristics and Applications |
| By Style/Volume | Portable | Small size (18–24L), portable, suitable for small laboratories or clinics with small volumes of items. |
| Vertical | The most common type (35–200L), small footprint, moderate capacity, widely used in general laboratories and medical units. | |
| Horizontal | Large capacity(150-500L), typically used in hospital Central Sterile Supply Departments (CSSD) or industrial production for large-scale processing. | |
| By Air Removal Principle | Gravity Displacement | Utilizes the principle that steam is lighter than air to "push" air out. Suitable for sterilizing solid instruments without pores (e.g., surgical forceps, glass bottles). |
| Pre-vacuum | Uses a vacuum pump to perform multiple vacuum cycles to thoroughly remove air, resulting in stronger steam penetration. Suitable for porous items or those with lumens (e.g., catheters, tightly wrapped dressings). | |
| By Application Field | Medical Type | Primarily used for sterilizing surgical instruments, dental tools, dressings, etc., emphasizing speed, efficiency, and strict infection control. |
| Laboratory Type | In addition to sterilization, it typically includes specialized modes for handling liquids (e.g., culture media) and agar, preventing liquid boiling over or agar solidification. | |
| Low-Temperature Type | Designed for heat-sensitive electronic devices such as cameras and endoscopes, using hydrogen peroxide plasma or ethylene oxide (EO) for sterilization at lower temperatures. |
3. Main Applications
Due to its powerful sterilization capability, the autoclave is mainly used in the following scenarios:
·Medical Field: Sterilizing reusable items such as surgical instruments, syringes, dental tools, surgical gowns, and gauze. It is a core piece of equipment for preventing hospital-acquired infections.
·Laboratory Research: Sterilizing culture media, glassware (petri dishes, test tubes), pipette tips, and biohazardous waste to ensure experimental accuracy and prevent contamination.
·Pharmaceutical Industry: Sterilizing production line equipment and filling tools for injectable solutions (ampoules, vials) to ensure the sterility and safety of pharmaceuticals.
·Biological Products: Sterilizing fermenters, piping systems, and packaging materials during the production of vaccines and biological preparations.
I. Core Sterilization Performance Features
· High Temperature and High Pressure, Thorough Sterilization: The sealed chamber generates saturated steam at 121 °C / 0.1 MPa or 134 °C / 0.2 MPa, far exceeding boiling water temperature. It can kill bacteria, viruses, fungi and heat-resistant spores, making it the most reliable method in moist heat sterilization.
· Strong Steam Penetration: Saturated steam has high density and strong penetrability, able to reach deep into crevices of instruments, interior of packages and porous materials to achieve uniform, full coverage sterilization.
· Fast and Efficient: Steam condensation releases large amounts of latent heat, enabling rapid heating. A standard sterilization cycle (including heating, holding and cooling) typically takes 20–60 minutes, much faster than dry heat sterilization.
· Verifiable Effectiveness: Equipped with biological indicators (e.g., Geobacillus stearothermophilus), chemical indicator strips / tape, allowing direct confirmation of successful sterilization.
II. Structural and Material Features
· Main Material: Mostly made of SUS304 / 316L stainless steel, acid resistant, alkali resistant, corrosion resistant and easy to clean, meeting medical and food grade hygiene requirements.
· Sealing and Door Operation: Self-inflating sealing ring + safety interlock (door cannot be opened until pressure / temperature reaches safe levels), preventing steam leakage and misuse. Quick opening design (handwheel / electric lock) ensures convenient operation.
· Chamber Design: Available in vertical, horizontal and benchtop models. Vertical types are mostly top loading to save space; horizontal types are suitable for large volume and long instruments.