41 Biosafety Manual Autoclave Safety Autoclaves use saturated steam under high pressure to achieve sterilizing temperatures. Proper use is important to ensure operator safety. Prevent injuries when using the autoclave by observing the following rules: • Wear heat-resistant gloves, eye protection, closed-toe shoes, and a lab coat, especially when unloading the autoclave. • Prevent steam burns and shattered glassware by making sure that the pressure in the autoclave chamber is zero before opening the door at the end of a cycle. Slowly open the autoclave door and allow any residual steam to escape gradually. • Allow items to cool for at least 10 minutes before removing them from the autoclave. Be careful with glass containers that contain liquids. Superheating is a condition that occurs often in autoclaves. Superheating occurs when liquids are at a temperature above their normal boiling point but do not appear to be boiling. In situations where personnel hurry to remove flasks or bottles from the autoclave, these superheated containers can explode or boil over. • Never put sealed containers in an autoclave. They can explode. Large bottles with narrow necks may boil over violently if filled too full of liquid. • Never put solvents, volatile, or corrosive chemicals (such as phenol, chloroform, bleach, formalin, fixed tissues, etc.), or radioactive materials in an autoclave. Call EH&S at (515) 2945359 if you have questions about proper disposal of these materials. Pressure Vessel Monitoring Autoclaves are classified as pressure vessels. Iowa Code requires that all autoclaves meet the American Society of Mechanical Engineers (ASME) Code and must be identified with a metal plate that is permanently affixed to the vessel. Autoclaves with an internal capacity greater than 5 cubic feet are subject to Department of Labor inspection and certification. Manufacturers of pressure vessels have been following the ASME standards and affixing the plates where required since 1909. Autoclaves used at Iowa State University must meet the following criteria: • All new autoclaves and pressure vessels must have ASME identification plates on them in order to be used or installed at any location.