Why Are Steam and Pressure Used in Sterilization?

Before we examine steam and pressure, let’s have a quick review of autoclaves. Autoclaves are the gold standard for sterilization worldwide. Autoclaves use water, heat, steam, and pressure in a vessel—not unlike a pressure cooker—to sterilize different types of tools, utensils, and materials. 

That said, you may wonder, why, specifically, are steam and pressure used in this equation? 

Steam is used for a few reasons. Wet heat is more effective at killing microorganisms than dry heat. So, in an autoclave, the ambient air is removed and the vessel is filled with steam. This is called saturated steam, and it saturates or completely fills the vessel including all the nooks and crannies of whatever you are trying to sterilize. 

The steam is more effective at transferring its heat or thermal energy to the pieces being sterilized, and these pieces or materials are heated up. They heat up faster with steam than they would with dry heat. The concentration of this steam within an autoclave is 97% air and 3% water. That ratio is important because if it was a different ratio, then the sterilization would take a shorter or longer time. 

Pressure 

Added pressure raises the temperature inside the vessel, which also aids in the sterilization process. In addition, the added pressure forces the steam into all the corners and surfaces of everything being sterilized. The use of pressure makes the transfer of heat to what is being sterilized faster, hotter, and more efficient. 

So, it is precisely the use of steam and added pressure that makes an autoclave so efficient at killing microorganisms and why you need both. 

If you need help choosing, repairing, maintaining, installing, operating, or validating an autoclave, this is our business and area of expertise for many years. Give us a call, in western Canada at (888) 818-4847. We can help with every aspect of autoclaves including choosing the right one for you. 

Alpha Scientific supplies, installs, and services medical equipment in western Canada. If you have any questions about this article or would like to talk to us about medical equipment, please call our toll-free number, (888) 818-4847, or email us at sales@alphascientific.ca.