Sterilizer Humidity Control via Pressure Differential
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Solution Overview
Problem
Conventional sterilizers using biocidal gases like ethylene oxide face challenges in efficiently controlling humidity levels due to the reactive nature of these gases, which can damage humidity sensors, leading to disruptions in sterilization cycles and slow humidification processes.
Innovation Solution
A humidity control system that utilizes constant pressure monitoring within the sterilizing chamber to ratiometrically calculate the next water injection quantity, accounting for load size and absorption rates, allowing for dynamic adjustment of gas delivery to achieve and maintain desired humidity levels efficiently.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a humidity sensor is placed in the sterilizing chamber to monitor humidity levels, then humidity control precision is improved, but the sensor is damaged by the reactive biocidal gas
Solution Approach 1:
The patent introduces an intermediary substance (salt solution or desiccant) that indirectly indicates humidity levels through pressure changes, protecting the pressure sensor from direct exposure to biocidal gas while still enabling accurate humidity monitoring through the relationship between pressure differential and relative humidity
2Reliability
If discrete humidity measurements are taken at various timepoints during humidification, then sensor protection is improved, but humidification speed deteriorates
Solution Approach 1:
The patent implements continuous pressure monitoring throughout the humidification process, allowing the control system to continuously adjust water injection based on real-time pressure differential readings, thereby maintaining both sensor protection and rapid humidification without discrete measurement interruptions
3Productivity
If constant pressure monitoring is used to control humidity, then humidification speed is improved, but system complexity increases
Solution Approach 1:
The patent replaces complex direct humidity sensing with a simpler pressure differential measurement system, using the physical relationship between pressure and humidity to achieve rapid control while minimizing the complexity of sensors and control electronics
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach enables rapid and precise control of humidity levels, reducing the risk of sensor damage and cycle disruptions, while ensuring effective sterilization by maintaining optimal humidity conditions for biocidal gas efficacy.
Implementation Method 1
a pressure sensor in fluid communication with the chamber for measuring pressure in the chamber
Implementation Method 2
a humidity sensor in selective fluid communication with the chamber for measuring a relative humidity value of the gaseous environment in the chamber
Implementation Method 3
a vaporized water injection system for injecting a quantity of water vapor into the chamber
Implementation Method 4
an appropriate charge of ethylene oxide gas can be released and allowed to act on the surfaces and be absorbed by the goods
Data Source
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Figure 3A
AI summary
Systems and methods for controlling humidity. Methods can include providing a chamber configured to receive objects to be sterilized; injecting a first quantity of water into the chamber; determining a pressure rise and a pressure drop in the chamber resulting from the first injection; calculating an absorption ratio (AR) as the ratio of the pressure drop to the pressure rise; sensing the humidity of the chamber after the first injection to determine a first humidity value (RH chamber); comparing the first humidity value to a pre-selected humidity value (RH setpoint) to determine a humidity error (RH error ), wherein RH error = RH setpoint - RH chamber; and injecting a second quantity of water into the chamber, wherein the second quantity of water is calculated based on the absorption ratio (AR) and the humidity error (RH error ). Systems can perform the method; and the systems and methods can be employed in a sterilizer.