Sterilization method
View Patent ↗By focusing on the fact that nitrogen dioxide exhibits an increased sterilizing effect among other sterilant gases including nitrogen oxide, the present invention is made to provide a sterilization method which may be suitably used for sterilizing items to be sterilized such as medical instruments which require increased reliability by using a high concentration NO 2 gas of 5,000 ppm or above, for example. An inside of a sterilizing chamber containing an item to be sterilized is humidified, and a concentration of NO 2 in the sterilizing chamber is made to be from 9 to 100 mg/L by filling a high concentration NO 2 gas.
1. A sterilization method comprising:
providing a humidifying apparatus for humidifying in a sterilizing chamber and an exhausting apparatus connected to said sterilizing chamber;
humidifying an inside of said sterilizing chamber containing an item to be sterilized; and
filling a high concentration NO 2 gas from a sub-chamber having a smaller internal volume than that of said sterilizing chamber to obtain a NO 2 concentration from 9 to 100 mg/L in the sterilizing chamber,
wherein said high concentration NO 2 gas is filled in said sterilizing chamber after humidifying with said humidifying apparatus, and said humidifying is performed in said sterilizing chamber after a pressure of an inside of said sterilizing chamber is decreased to less than 56 KPa absolute,
wherein the filling of said high concentration NO 2 gas is a step-by-step process comprising filling a part of said high concentration NO 2 gas and then further introducing a remaining part of said high concentration NO 2 gas one or more times to increase the number of NO 2 molecules and an internal pressure in said sterilizing chamber which contains the filled part of said high concentration NO 2 gas, and
wherein an ambient temperature inside of said sterilizing chamber filled with said high concentration NO 2 gas is maintained from 10 to 60° C.
2. The sterilization method according to claim 1 , wherein said inside of said sterilizing chamber is humidified to obtain a relative humidity from 10 to 90% R.H.
3. The sterilization method according to claim 1 , wherein said humidifying apparatus is configured to include an evaporation portion communicating with said sterilizing chamber, and a heater for heating said evaporation portion.
4. The sterilization method according to claim 1 , wherein said humidifying is performed or said high concentration NO 2 gas is filled in said sterilizing chamber after a pressure of an inside of said sterilizing chamber is decreased to 0.01 KPa to 1 KPa absolute.
5. The sterilization method according to claim 1 , wherein said high concentration NO 2 gas is generated by displacing a gas mixture including nitrogen and oxygen into a plasma state with a plasma generator.
6. The sterilization method according to claim 1 , wherein a pressure difference between an outside atmospheric pressure and a pressure in said sterilizing chamber at a time of completing a filling of said high concentration NO 2 is from −1 KPa to −95 KPa absolute.
7. The sterilization method according to claim 1 , wherein an item to be sterilized having a narrow opening with an internal diameter of 1 to 4mm is contained in said sterilizing chamber between 10 and 480 minutes, and wherein said sterilizing chamber is humidified to reach a relative humidity from 10 to 90% R.H., and is filled with said high concentration NO 2 gas to obtain an NO 2 concentration from 9 to 100 mg/L in said sterilizing chamber.
8. The sterilization method according to claim 1 , wherein an item to be sterilized having crossover opposing surfaces is contained in said sterilizing chamber between 10 and 480 minutes, and wherein said sterilizing chamber is humidified to reach a relative humidity from 10 to 90% R.H., and is filled with said high concentration NO 2 gas to obtain an NO 2 concentration from 9 to 100 mg/L in said sterilizing chamber.