Sterilizer with a humidity control system
The disclosed sterilizer includes a humidity control system for controlling humidity. The sterilizer for sterilizing objects comprises a chamber for receiving objects to be sterilized and a humidity control system. The humidity control system comprises a water control system which can be connected to a water source for injecting a first quantity of water vapor into the chamber, a pressure sensor in fluid communication with the chamber for measuring pressure in the chamber, a humidity sensor in fluid communication, or in selective fluid communication, with the chamber for sensing a first humidity value (RH chamber ) of the first quantity of water vapor in the chamber; and a controller configured to inject a second quantity of water vapor into the chamber.
1. A sterilizer for sterilizing objects comprising:
a chamber for receiving objects to be sterilized;
a humidity control system comprising:
a water control system which can be connected to a water source for injecting a first quantity of water vapor into the chamber;
a pressure sensor in fluid communication with the chamber for measuring pressure in the chamber;
a humidity sensor in fluid communication, or in selective fluid communication, with the chamber for sensing a first humidity value (RH chamber ) of the first quantity of water vapor in the chamber; and
a controller configured to inject a second quantity of water vapor into the chamber, wherein the controller is configured to:
determine a pressure drop and a pressure rise in the chamber resulting from the first quantity of water vapor injected into the chamber,
calculate an absorption ratio (AR) as the ratio of the pressure drop to the pressure rise,
compare the first humidity value (RH chamber ) to a pre-selected humidity value (RH setpoint ) to determine a humidity error (RH error ), wherein RH error =RH setpoint −RH chamber , and
determine a second quantity of water vapor to be injected into the chamber based on the absorption ration (AR) and the humidity error (RH error ).
2. The sterilizer of claim 1 , wherein the controller is configured to calculate an absorption coefficient (AC), wherein AC=1+(P gain,AR *AR), where P gain,AR is a proportional gain constant, and wherein the second quantity of water vapor is calculated based on the absorption coefficient (AC) and the humidity error (RH error ).
3. The sterilizer of claim 2 , wherein the second quantity of water vapor is proportional to the absorption coefficient (AC) and the humidity error (RH error ).
4. The sterilizer of claim 1 , further comprising a water injection valve for injecting the first quantity of water vapor or second quantity of water vapor.
5. The sterilizer of claim 4 , further comprising a timer measuring an injection time (t inject ) of the water injection value.
6. The sterilizer of claim 5 , wherein the injection time (t inject ) is a constant value.
7. The sterilizer of claim 6 , wherein the injection time (t inject )=P gain *AC*RH error , where P gain is a proportional gain constant used to scale the humidity error (RH error ).
8. The sterilizer of claim 1 , further comprising a RH sample valve.
9. The sterilizer of claim 8 , wherein the humidity sensor is located in a humidity manifold, and wherein the RH sample valve is located between the chamber and the humidity manifold.
10. The sterilizer of claim 1 , further comprising objects to be sterilized within the chamber and sealing the chamber.
11. The sterilizer of claim 1 , further comprising a biocidal gas control system which can be connected to a biocidal gas source for controlling the release of biocidal gas into the chamber.