New USP Guidance on Heat Sanitization: Keep Temperatures Below 80°C
USP concurs: SnowPure’s experience says that heat sanitization should be between 72-80°C:
- Bacteria are killed at temperatures above 65°C.
- Most bacteria are killed at 60°C, and essentially all bacterial are killed above 65°C.
- Two common protocols have emerged for sanitizing validated high purity water systems:72°C for 30-60 minutes (bacteria killed in seconds)
- 80°C for 15-30 minutes (bacteria killed in milliseconds)
SnowPure’s HTS “High Temperature Stable” EDI’s are designed for temperatures up to 85°C, but we recognize that module lifetime will be longer if you stay in the 72-80°C range.
The USP (US Pharmacopeia) used to recommend temperatures of “at least” 80°C for heat sanitization. However, in the new USP 1231 the recommended temperature for hot sanitizing has changed.
“The previous recommendation of “at least 80°C” has been lowered to 65-80°C. Now temperatures far in excess of 80°C are explicitly deemed inadvisable.”
Reasoning: a temperature of 80°C is very “forgiving” of cooler locations which can still be sanitized even with a 10-15°C temperature loss as heat penetrates throughout the system by convection and conduction, so it is very effective. Cooler temperatures (down to 65°C) can also be used but is “unforgiving” of yet cooler locations such as outlet valves off of the main loop. So such cooler locations must be flushed with this slightly cooler hot water in order to assure that all surfaces reach sanitizing temperatures greater than 60°C. Unless systems are specifically designed for this, temperatures hotter than 80°C can impact the longevity of system materials (e.g. gaskets and diaphragms). A temperature of 80°C is hot enough to kill the most heat resistant biofilm organisms that will colonize a water system (D value of about 5 milliseconds).
SnowPure Article: Heat Sanitization Basics
From the USP, FAQ #19: www.usp.org
Another valuable discussion from the GMP Compliance Organization