Controlled dosing of liquid cryogen
AssigneeVacuum Barrier Corporation
InventorsErik Robert Showers, John Walker Ross, David Tucker
Life of this patent
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Abstract
An aseptic liquid cryogen dosing head has a liquid cryogen reservoir in communication with a dosing outlet. An electromagnetic actuator is attached to an upper end of a dosing valve stem and is operable to move the dosing valve stem to open and close the dosing outlet. An air-tight seal extends about the dosing valve stem and separates the liquid cryogen reservoir from a cavity between the seal and the electromagnetic actuator. A controller is operable to perform a head leakage test, including pressurizing the cavity with a pressure higher than a pressure within the reservoir, to check for leakage past the seal; and pressurizing the reservoir to check for leakage from the liquid cryogen reservoir.
Claims19
An aseptic liquid cryogen dosing head, comprising
- a liquid cryogen reservoir in communication with a dosing outlet;
- a dosing valve stem extending through the liquid cryogen reservoir and having a lower, distal end configured to selectively open and close the dosing outlet;
- an electromagnetic actuator attached to an upper end of the dosing valve stem and operable to move the dosing valve stem to open and close the dosing outlet;
- a seal extending about the dosing valve stem and separates the liquid cryogen reservoir from a cavity between the seal and the electromagnetic actuator, the seal providing an air-tight seal during operation;
- and
- a controller operable to perform a head leakage test, including
- pressurizing the cavity with a pressure higher than a pressure within the reservoir, to check for leakage past the seal;
- and
- pressurizing the reservoir to check for leakage from the liquid cryogen reservoir.
A method of sterilizing a liquid cryogen dosing head, comprising
- performing a system leakage test by pressurizing a first cavity between a dosing valve stem seal and an electromagnetic dosing actuator, as well as a second cavity on an opposite side of the dosing valve stem seal, to check for system leakage;
- testing for leakage past the seal by reducing pressure in the second cavity and, with the second cavity pressure reduced, monitoring pressure in the first cavity over a predetermined time interval;
- and then
- in response to passing the seal leakage test, introducing a sterilization fluid to the second cavity and maintaining the sterilization fluid in the second cavity under conditions that cause sterilization of the second cavity and a dosing valve stem extending from the dosing valve stem seal to a liquid cryogen dosing outlet, while maintaining sufficient pressure in the first cavity to keep the dosing valve stem seated at the liquid cryogen dosing outlet.
Dependencies are inferred from the claim text.