Your Go-To Guide for Autoclave Safety [w/ Free Checklist!]

Autoclaves, also known as sterilizers, are designed to disinfect, decontaminate, and sterilize laboratory equipment using incredibly hot, pressurized steam. As a result, there are a number of potential risks associated with operating an autoclave, such as steam burns, hot fluid scalds, and hand and arm injuries when closing the autoclave door. In order to avoid bodily harm, it’s imperative any individual operating an autoclave be aware of the potential hazards, as well as the necessary safety precautions.

Basic Autoclave Safety Precautions

• Prior to operating an autoclave, laboratory personnel should undergo comprehensive training customized to the particular make and model of the unit.
• Always wear personal protective equipment — a lab coat, heat-resistant gloves, and safety glasses or goggles — and close-toed shoes. Both the lab coat and gloves should be long enough to prevent any skin on the arm from being exposed. Depending on the application, it might also be appropriate to wear a rubber apron and/or a face shield.
• Do not seal containers, as the increased pressure within an autoclave can present an explosion hazard (unless you have a special cycle that is specifically designed for sealed containers)
• Do not open the door to an autoclave if there is water running out of the bottom. Equipment malfunctions and clogged drain lines can cause hot water to build up, posing a scalding risk.
• Do not open the door when a sterilization cycle is in process, as this can cause the cycle to abort.
• Do not open the autoclave door until the pressure has reached zero and the temperature is below 100°C to avoid burns or scalding.
• Never stand directly in front of the autoclave door.
• Use a designated liquid cycle to sterilize liquids. Liquid cycles prevent boil-over by slowly releasing the chamber pressure during the exhaust phase, thereby enabling the liquid load to cool off gradually. Liquid cycles can also prevent liquids from superheating or achieving a temperature above their normal boiling point.
• Inspect all glassware prior to loading. Older glassware or glassware with preexisting fissures or fractures are less stable and therefore more liable to break during sterilization.
• Always allow materials, including racks and containers, to cool before unloading. Additionally, be sure to wear heat-resistant gloves when unloading.
• Immediately clean any spilled materials or condensate to prevent slip-and-fall accidents.
• Be mindful to keep arms and hands clear of the autoclave door when closing.
• Report any accidents or injuries to the appropriate authorities.
• Notify facilities support if you encounter any of the following:
  • No steam
  • Gasket deterioration
  • Leaking valves
  • Insufficient jacket pressure
  • Insufficient temperature
  • Unexpected fluctuations in temperature or pressure during the cycle
  • Steam escapes from around the door during the cycle
  • Water is leaking from the chamber
  • Items are still wet even after a dry cycle
• Perform routine preventative maintenance to reduce autoclave downtime, equipment malfunction, and other risk factors.

15 Materials You Should Never Autoclave

Although autoclaving is the preferred method of sterilization for many laboratories, for the sake of safety, there are certain items and materials that should not, under any circumstances, be placed in an autoclave. These include:

1. Sharps (unless placed in a designated sharps’ container)
2. Sealed containers (unless you have a special cycle designed for sealed containers)
3. Hazardous chemicals or items that have been contaminated by hazardous chemicals
4. Radioactive materials
5. Pathological waste; this includes animal or human carcasses, tissues and organs
6. Flammable or corrosive materials
7. Chlorine
8. Hypochlorite
9. Bleach
10. Chlorides
11. Sulfates
12. Seawater (unless you have a chamber fabricated of Nickel-Clad material)
13. Polystyrene
14. Polyethylene
15. Polyurethane

How to Safely Prepare Materials for Sterilization

Safety is a priority not only when determining which materials are approved for sterilization, but also how to prepare approved materials for sterilization.

In order to prevent the autoclave from damaging the load and to protect users from potential harm, laboratory personnel should carefully inspect all glassware for cracks and make sure that all plastics are autoclave-safe. Cracked glassware can easily break under intense pressure, and the very high temperatures at which autoclaves run can melt certain plastics. Each of these scenarios poses a safety hazard — either in the form a cut or a burn — to personnel when they attempt to remove the broken glassware or melted material from the autoclave chamber. When sterilizing liquid loads, make sure that containers are loosely sealed to prevent possible explosions (and scalding) and select a liquid sterilization cycle.

It’s also important to check inside the autoclave prior to loading materials because debris from previous sterilization cycles can collect in the chamber or on top of the drain strainer. This debris can prevent the unit from properly sterilizing equipment.

Finally, when loading the unit, be mindful to space items and never to overload the autoclave. This not only prevents goods within the autoclave chamber from bumping up against and potentially damaging each other, but also makes the autoclave easier to unload once the sterilization cycle is complete.

Basic Autoclave Operating Instructions

Listed below are basic instructions for operating a standard Consolidated autoclave.

Note: These should serve as a basic overview of guidelines and are not intended to be a replacement for a manufacturer’s operating instructions. It’s imperative that laboratory personnel review the owner’s manual prior to operating the autoclave.

1. Carefully load materials into the autoclave, making sure that goods are evenly spaced out.
2. Use the autoclave control panel to select the cycle duration and cycle type based on the size and contents of the load.
3. Once the cycle is complete, allow goods to reach a safe temperature before attempting to unload the autoclave.
4. If goods are still warm, set them aside in designated area to cool.
5. Leave the autoclave jacket on and engaged in case other laboratory personnel need to use it.
6. Update the autoclave log sheet with the time and date, contents of the load and cycle type.

For a more in-depth list of operating instructions, please refer to our guide to standard autoclave procedure.

Your Free Autoclave Safety Checklist

Post this safety checklist in an easy-to-see area, ideally next to the autoclave log sheet.

• Have you received the appropriate training to operate this unit?
• Are you wearing the appropriate PPE?
• Are the items you intend to sterilize autoclave-safe? If not — that is, if they are flammable, reactive, corrosive, toxic or radioactive — please follow the appropriate protocol for safe disposal.
• If you’re sterilizing plastic, have you checked to see whether it is autoclave-safe?
• If you’re sterilizing glassware, have you checked to see whether there are any cracks?
• If you’re sterilizing liquids, have you made sure that the container lids have been loosened? All containers of liquid should be placed in secondary containment like a shallow autoclave-safe tub or tray.
• Are there any issues with the door gasket? Is it intact and still pliable?
• Is the autoclave chamber clear of debris?
• Is the drain strainer clear of debris?
• Is there sufficient space between the items loaded into the autoclave?
• Do you have a secondary containment tray in place?
• Has the jacket reached sufficient temperature and pressure?
• Have you locked the autoclave door?
• Have you selected the appropriate sterilization cycle for the load?
• Have you recorded the cycle on the log sheet?

If you’re looking for additional autoclave safety guidance, why not talk to the experts? Consolidated Sterilizer Systems has been producing state-of-the-art sterilization solutions for over 70 years — and in that time, we’ve learned a thing or two about autoclave safety. Contact us today to get in touch with an autoclave solution specialist.