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Temperature profiles and sterilization within a dead-ended tube
Journal of Parenteral Science and Technology : a Publication of the Parenteral Drug Association
|July 1, 1992
Summary
Steam-in-place (SIP) sterilization of complex biotech equipment is challenging. This study found that tube orientation and location significantly impact sterilization times and effectiveness in dead-ended geometries.
Area of Science:
- Biotechnology
- Sterilization Science
- Process Engineering
Background:
- Increasing complexity of biotechnology processing equipment necessitates advanced sterilization methods like steam-in-place (SIP).
- Lack of quantitative guidelines for SIP sterilizable equipment design, particularly for challenging dead-ended geometries, requires extensive biological testing.
- Limited data exists on how tube orientation, length, and diameter affect SIP sterilization times.
Purpose of the Study:
- To investigate the impact of location within a dead-ended tube and tube orientation relative to gravity on SIP sterilization.
- To characterize kill kinetics and determine sterilization times for dead-ended geometries under various conditions.
- To provide recommendations for sterilization and validation testing of these challenging geometries.
Main Methods:
- Examined temperature profiles and biological kill of Bacillus stearothermophilus in dead-ended tubes.
- Tested four different tube orientations with respect to the gravitational vector.
- Characterized kill kinetics by measuring time to start of kill and cycle log reduction (CLR) times.
Main Results:
- Sterilization effectiveness, indicated by time to start of kill and CLR times, increased with distance up the tube and more horizontal orientations.
- CLR values were up to ten times greater than those achieved with saturated steam alone.
- Projected sterilization times were highly dependent on tube orientation, highlighting significant challenges in horizontal positions.
Conclusions:
- Tube orientation and location within dead-ended geometries critically influence steam-in-place sterilization efficacy.
- More horizontal tube orientations and positions further from the steam inlet require longer sterilization times and show reduced effectiveness.
- Recommendations are provided for improved sterilization strategies and validation testing protocols for dead-ended geometries in SIP systems.