Autoclaves are common in research labs on campus and are used to sterilize glassware, lab instrumentation, and solutions.
While the controls for different brands of autoclaves may have their own unique characteristics for loading, load sizes, cycle types, and cycle settings, autoclave hazards remain the same.
Autoclave users should be aware of three primary hazards:
Burn Hazard: Steam from the autoclave is very hot and can cause burns. Caution must be taken when opening the door to avoid contacting the escaping steam and heat. Caution must also be taken when loading and unloading, as contents inside will be extremely hot.
Explosion Hazard: Explosions can occur when the seal of the door malfunctions or when the autoclave is loaded improperly. Pressure and heat in the chamber will escape rapidly with a potential for serious injury.
Heavy Lifting Hazard: Never overload trays inside an autoclave. Remember: you will have to remove them when extremely hot. Use autoclave rack carts to move removeable racks or other carts to transfer hot materials. Minimize travel distance and size of load whenever possible.
Note: Hazardous chemicals should NEVER be placed in an autoclave. Autoclaving oxidizing (e.g. bleach) or flammable liquids can cause an explosion if autoclaved.
Compatible/Incompatible Materials For Autoclaves
- Tissue Culture Flasks
- Surgical Instruments
- Pipette tips
- Media Solutions
- Animal food and bedding
- Polypropylene (Secondary containers)
- Stainless steel
- Acids, bases and organic solvent
- Chlorides, sulphates
- Chlorine, hypochlorite, bleach
- Non-stainless steel
- Low density (LDPE) and High density polyethylene(HDPE)
Never autoclave the following:
- Flammable, reactive, corrosive, toxic or radioactive materials
- Household bleach
- Any liquid in a sealed container (loosen lids halfway or cover with tin foil)
- Any material contained in such a manner that it touches the interior surfaces of the autoclave
- Paraffin-embedded tissue
Do NOT autoclave the following plastics:
- Polystyrene (PS, #6)
- Polyvinyl chloride (PVC, #3)
- Nylon, acrylic, low-density polyethylene (LDPE, #4)
- High-density polyethylene (HDPE, #2)
- Lab ware and polyurethane tubing are NOT autoclavable under any conditions
Please review the following to ensure you are autoclaving approved materials.
Only Pyrex® or Type I borosilicate glass can be autoclaved. When autoclaving liquids in Pyrex® containers, do not fill the container more than 2/3 full. Do not seal the container.
- Polypropylene (#5) can resist autoclave temperatures. Polypropylene secondary bins are often used to hold materials and contain liquids that are autoclaved.
- Polycarbonate (#7) can also withstand high temperatures.
Gloves must be placed inside of an autoclavable biohazard bag and exposed to a steam setting; gloves will melt slightly but will not burn when autoclaved in this manner.
Most metals are designed for extreme conditions and are intended to be sterilized. Make sure to remove any plastics, liners and other items that may melt or combust.
Paper is combustible and should NOT be placed directly inside an autoclave. It should be autoclaved in a waste bag on a biobag setting to prevent fire.
No liquid should be sealed in a container and autoclaved. Fill 2/3 of the container and loosen caps. They should autoclaved in a steam producing cycle.
Control Autoclave Hazards
Provide (and document) autoclave-specific training to all users. Include a review of the autoclave manual as well as specific safety warnings and procedures.
- Best Management Practice: Post the standard operating procedure for the autoclave on the side or wall adjacent to the instrument.
Wear appropriate personal protective equipment.
- Face shield with safety glasses underneath: Recommended when opening the autoclave door.
- Heat-resistant gloves: Be careful to never touch the inside of the autoclave with unprotected skin.
- Lab coat and a heat-resistant apron: This protects from splatter when removing hot glass or liquids.
- Long pants: This provides additional protection from splatter or splash. You should have no exposed skin on the arms (burn hazard) or legs (splash hazard) when removing items from the autoclave.
- Closed-toe shoes are required for all laboratory work (no sandals, crocs, Tevas, etc).
Ensure that there are a few inches of headspace in each container so that there is room for heated liquids to expand.
Cool glassware slowly. When the autoclave cycle is complete, carefully open the door and allow the glassware to cool inside for at least 10 minutes. This may reduce the risk of breakage or severe injury.
When unloading a large amount of items, remove items one at a time and limit the distance you have to travel by moving items from the autoclave to a cart, then the cart back to the lab.
If materials are not autoclaveable, do not place them in the autoclave; they could melt or shatter during a sterilization cycle. If you are unsure if a material can be safely autoclaved, do not try it until autoclaveability is determined.
Autoclaves must have proper exhaust ventilation (e.g. a canopy hood) to remove heat and humidity.
Autoclave Maintenance and Repairs
Autoclaves require preventative maintenance. Consult the manual for the autoclave in your lab or building and follow prescribed maintenance and repair recommendations. UVM Technical Services Partnership has technicians who can perform maintenance and repairs to autoclaves.
Some of the routine maintenance that is recommended includes the following:
- The plug screen or drainer should be removed with heat-resistant gloves, checked, and cleaned frequently to ensure that it is free of dirt, dust, or sediment that may collect and cause a clog.
- Gaskets, doors, shelves and walls should be visually inspected before each use. Look for residue buildup and wear.
- Some autoclaves have an air filter in the exhaust located directly above the autoclave. The filter must be checked regularly to ensure that it is not clogged. Replace the filter as required by the manufacturer.
A new autoclave may have installation requirements that vary from the old autoclave. Physical Plant Department (PPD) personnel may be available to help coordinate the installation of a new autoclave. Submit a FAMIS Work Order request to get PPD's assistance and expertise when connecting any piece of equipment to existing building systems. Autoclaves must be vented properly. Plumbing and electrical needs will also need to be addressed.
An autoclave is a pressure vessel and is required to be certified and tested upon installation and every few years thereafter. Individual departments must coordinate the certification and inspection process of department-owned autoclaves. Contact UVM's Physical Plant Department by submitting a work order.
If damage or problems are found, the autoclave should be removed from service and a vendor contacted for repairs.
Other Autoclave Repair/Maintenance Vendors Include The Following: