Sterilization system for a blow/fill/seal machine
A fill assembly sterilization system for a blow/fill/seal machine utilizes a closed loop circulation of sterilant containing gas. A typical sterilant is nitrogen dioxide. The closed loop includes a shroud that defines a plenum and encloses the fill system. Optionally, at least one high efficiency particulate absorption (HEPA) filter is provided in the closed loop. Sterility assurance level of 10 −6 can be achieved by subjecting the fill system to the sterilizing gas for at least 20 minutes at a temperature in the range of about 18° C. to about 30° C.
1. A sterilization system for a blow/fill/seal machine having a fill assembly, and comprising
a shroud enclosing the fill assembly and defining a plenum, a sterilizing gas inlet and a sterilizing gas outlet;
an external conduit defining at least one sterilizing gas flow passageway between said sterilizing gas inlet and said sterilizing gas outlet;
a blower in the external conduit adjacent to said sterilizing gas inlet for introducing into and circulating the sterilizing gas through the shroud;
a sterilizing gas source connected to the external conduit upstream from the blower in confined flow communication with the blower; and
a humidifier and a humidified conduit in confined flow communication with the external conduit between the blower and a HEPA filter.
2. The system in accordance with claim 1 wherein the sterilizing gas contains nitrogen dioxide.
3. The system in accordance with claim 1 , further including a humidity sensor in communication with the external conduit.
4. The system in accordance with claim 1 further including a sterilant concentration sensor in communication with the external conduit.
5. The system in accordance with claim 1 , further including a purge air conduit in confined flow communication with the external conduit upstream from the blower.
6. The system in accordance with claim 1 further including an exhaust conduit in confined flow communication with the shroud.
7. The system in accordance with claim 1 further including a sterilant sensor in the exhaust conduit.
8. The system in accordance with claim 1 further including a pressure gauge in communication with the shroud and a pressure gauge in communication with the external conduit.
9. The system in accordance with claim 1 wherein at least one high efficiency particulate absorption (HEPA) filter is in the sterilizing gas flow passageway between the blower and said sterilizing gas inlet.