Steam Sterilization Cycles, Part 7: Product Lifecycle Testing in an Autoclave

In our 7^th installment of the Advanced Cycles Series, we explore automated product lifecycle testing in an autoclave. Repeated exposure to an autoclave chamber’s extreme temperature and pressure conditions allows Quality Control Specialists to sharply accelerate product aging and evaluate the lifecycle of a product. Typically, this process requires that an individual (e.g. technician, scientist, engineer, etc) spend countless hours in front of an autoclave. What if you could program the autoclave to run multiple sterilization cycles (over multiple hours or days) with the press of a single button?

Background

The purpose of performing a lifecycle test isn’t necessarily to kill microbes. Instead, this testing is useful for simulating how products age over time when exposed to sterilization conditions (e.g. high temperature and pressure). Moisture, heat and pressure are factors known to accelerate the degradation of materials like plastics, polymers, natural fibers and some metals. Running multiple back-to-back cycles is especially useful, and often times required, to validate the integrity of items constructed of these materials. Furthermore, certain chemical reactions occur at quicker rates – according to Arrhenius’ equation every 10°C increase in temperature doubles the rate of a chemical reaction. This accelerated testing can compress a year’s worth of testing down to just weeks or even days.

How It Works

Most autoclaves on the market are not equipped to run repeated, back-to-back cycles, without having the user present to initiate each cycle. To run a standard Gravity, Vacuum or Liquids Cycle, the operator initiates the process by selecting the Cycle Type, entering the appropriate sterilization time and temperature, and pressing the start button. At the end of the cycle, the operator must open the sterilizer door and remove the load before another cycle can be initiated. Product lifecycle testing in the above fashion is very time consuming, as it takes up valuable time to monitor the autoclave and restart every cycle.

What if this process could be automated? This option exists on modern controllers and is quite useful. The operator will simply select the Cycle Type (e.g. gravity cycle, 250F, 45min) and activate the “Repeat Cycle” feature by inputting the desired Number of Repetitions, End-of-Cycle Temperature, and Wait-Time between Cycles. One could theoretically enter 1,000 repetitions thereby simulating years worth of cycles in days. Some autoclaves can also be configured to simulate the effects of thermal cycling and thermal shock by incorporating a Rapid Cool Cycle.

Industries that Perform Product Lifecycle Testing

Textiles: Medical cotton based fabrics sterilized at 270°F retained greater strength after 100 cycles than the same items sterilized at 250°F for a longer cycle time.[1]

O-Rings & Gaskets: Items used in high temperature sealing applications.

Consumer Goods: Products to be used or stored in high heat and/or humidity environments like deserts or rain forest. Products that may be stored in buildings or locations with uncontrolled ambient conditions.

Closed Cell Foam Insulation: Accelerated aging in an autoclave testing shows a decrease in tensile strength with prolonged exposure to heat and humidity.[2]

Medical: Designers of reusable medical instruments can test instrument resilience to steam sterilization. This helps determine number of times an instrument can be re-used before disposal is necessary. Prosthetics and other medical devices also undergo accelerated aging tests to ensure they perform properly over time.

Conclusion

Product lifecycle testing applies the primary components of steam sterilization, heat and pressure, to simulate how materials will age over time. Typically, running multiple cycles on an autoclave is cumbersome, as users have to open the door and reset the controls for each new cycle. Consolidated’s “Repeat Cycles” feature automates the process so the autoclave can run uninterrupted, saving time and reducing costs.

Contact us today for your product lifecycle testing needs.

[1] Henry, P.S.H., Journal of Applied Bacteriology, Volume 27. “The Effect on Cotton of Steam Sterilization with Pre-Vacuum”

[2] Broughton, William R. National Physical Laboratory, Teddington, Middlesex, UK “Towards Ageing Protocols for Service in Hostile Conditions”