How long to autoclave liquids

Therefore, the bottles must be open or at least vented the lid must be slightly open. If venting the bottles is forgotten or done improperly, the liquid inside cannot boil during the recooling phase and thus will not cool down. This poses a considerable hazard, as these bottles may explode during removal from the autoclave and the liquid contained therein may evaporate spontaneously — similar to a delayed boiling.

Cooling by radiation has considerable advantages as compared to cooling by evaporation. During quick cooling with support pressure, the pressure vessel is cooled down across its entire surface via externally attached cooling coils containing cold water.

Before cooling is activated after the sterilization phase, the steam inside the pressure vessel is replaced by sterile-filtered compressed air. This pressurized air reliably prevents the liquid from boiling during the cooling phase. Heat is transferred from the liquid to the cold walls of the pressure vessel by means of radiation and the liquids thus are cooled down.

Quick cooling with support pressure allows for a substantial gain in productivity, as process time compared to self-cooling is considerably reduced. Furthermore, all hazards and disadvantages described for cooling by evaporation delayed boiling, loss of liquid, over boiling, no cooling of hermetically sealed bottled are reliably eliminated, as the liquid does no longer boil. Opening or venting the bottles is no longer required.

State-of-the-art autoclaves allow to further optimize the cooling of liquids in modules. This further increases productivity but also influences the quality of the liquids to be sterilized. Many liquids contain ingredients that are not very heat-stable. The liquids must be sterilized, but the time they will be exposed to heat impact, should be as short as possible so that heat-labile ingredients do not suffer negative impacts. Module 1 — Radial ventilator The radial ventilator generates an airstream inside the pressure vessel of the autoclave during the cooling phase.

This airstream forces the heat from the bottles onto the walls of the pressure vessel cooled by quick cooling with support pressure. Module 2 — Ultracooler The Ultracooler is an additional water-cooled heat exchanger, integrated directly into the pressure vessel of the autoclave. This allows to remove the heat from the bottled exactly there where the heat is.

Inside the pressure vessel. Note : As radial ventilator and Ultracooler are installed inside the pressure vessel, take care that they will not reduce the usable space available inside the autoclave. When sterilizing solids e. Namely on all inner and outer surfaces of the product to be sterilized. Many autoclaves do not remove air reliably from the autoclave and from the product.

If air remains inside the autoclave and the product, no sterilizing effect is possible, as only steam transports the thermal energy required to reliably deactivate microorganisms. Illustrations 5 and 6 show an ineffective air removal using the example of a box with pipette tips as well with destruction bags. If the autoclave is just simply heated up, air is displaced and a steam atmosphere builds up inside the pressure vessel of the autoclave but air remains inside the product to be sterilized.

Air remaining inside the product, however, prevents the steam from entering where its thermal energy is needed to achieve a sterilizing effect. At the same temperature as steam e. Effective air removal For a complete and reproducible removal of air from the autoclave and the product to be sterilized, a fractionated pre-vacuum is to be used.

Therefore, the autoclave is equipped with a vacuum system. During the heat-up phase, vacuum cycles take place for effective air removal followed by steam injections. Usually, a threefold fractionated pre-vacuum is applied — depending on the product, however, even more fractions may be necessary. Drying of solid objects — Superdry. Solids such as instruments or empty glassware are usually put inside a drying oven following the sterilization process.

State-of-the-art autoclaves allow for drying solids directly after the sterilization process. Sterilization and drying in one process. Further handling of the sterilization material possibly causing recontamination is not necessary.

Sterilization of biologically hazardous substances is a special challenge. During the heating-up phase, the air inside the autoclave is replaced with steam. Air is displaced from the autoclave and released into the room where the autoclave is installed. TRBA — Technical Regulations for Biological Working Materials requires that, in labs from Security Level BSL2, process exhaust air from an autoclave must be treated as the exhaust air may be contaminated by microorganisms from the product to be sterilized.

An appropriate process must be used. In the case of autoclaves , it is usually filtration. Therefore, the autoclave can be equipped with an air exhaust filter. All air displaced from the autoclave passes the filter with microorganisms being retained in the filter. TRBA deals only with exhaust air released from the autoclave, but not the condensate collected. During the sterilization process, steam condenses on the product and thus turns again into water condensate.

This water may also be contaminated with microorganisms. During qualification it is verified, whether a device is suitable for its intended use and whether a process — e.

Generally, the qualification process is split into three basic parts:. IQ — Installation Qualification Verification, whether a device was manufactured and installed according to specifications. If necessary, place container on its side to maximize steam penetration and avoid entrapment of air. Use only autoclavable bags to package waste. Do not allow bags to touch the interior walls of the autoclave to avoid melting of plastic. Ensure sufficient liquid is packed with contents of autoclave bags if dry.

Place soiled glassware and lab ware in secondary containers and autoclave them in the solids cycle. Loosen caps or use vented closures. In case of clean glassware and wrapped instruments, lay them in a secondary container before autoclaving in wrapped goods cycle. For secondary containment, use autoclave trays made out of polypropylene, polycarbonate or stainless steel.

The trays should have a solid bottom and sides to contain the contents and catch spills. Choose appropriate cycle for the material. Incorrect selection of cycle may damage the autoclave, cause liquid to boil over or bottles to break. Start your cycle and fill out the autoclave user log.

A completed cycle usually takes between 1 to 1. Close and lock door. Do not attempt to open the door while autoclave is operating. Unloading Ensure cycle has completed and both temperature and pressure have returned to a safe range.

Wear PPE described above, plus an apron and face shield if removing liquids. Stand back from the door as a precaution and carefully open door no more than 1 inch.

This will release residual steam and allow pressure within liquids and containers to normalize. Allow the autoclaved load to stand for 10 minutes in the chamber. This will allow steam to clear and trapped air to escape from hot liquids, reducing risk to operator. Do not agitate containers of super-heated liquids or remove caps before unloading. Do I use a 30 minute? A 45 minute? Above you will find a table which Steris uses as a roadmap for assuming a high degree of sterility assurance in your autoclave runs.

Please understand that these are only guidelines and are in terms of "time" as a function of how much "volume per flask". The minimum sterilization time, however, can vary significantly due to how many flasks you are sterilizing, how you place the flasks in the autoclave, and what type of liquid you are sterilizing. For example, the times below are for "water-like" solutions.