Calibration system and housing
AssigneeMinnesota Mining and Manufacturing Company
InventorsRoxanne E. Wall, Thomas P. Maxwell
Life of this patent
Estimating the term…
Abstract
A calibration system comprising a sensor cassette including at least one sensor to be calibrated and a housing having a liquid passage including a chamber. The housing is coupled to the sensor cassette to place the liquid passage in fluid communication with the sensor cassette. The housing has a gas injection passage through which a gas can be injected into the liquid passage to mix with a calibration liquid in the housing. A gas vent vents the gas from the housing. Porous media is provided in the chamber. The gas and calibration liquid pass through the porous media, and the porous media assists in rapid mixing of the gas and the calibration liquid.
Claims29
A calibration system comprising:
- at least one sensor to be calibrated, said sensor being responsive to a characteristic of a gas;
- a housing having a liquid passage including a chamber, said housing being coupled to the sensor to place the liquid passage in fluid communication with the sensor;
- a sterile liquid in said liquid passage;
- said housing having a gas injection passage through which a gas can be injected into the liquid passage to mix with the liquid;
- means for venting the gas from the housing;
- porous medium comprising an open cell foam positioned down stream from said gas injection passage and in said chamber so that the gas and liquid can pass through the open cell foam to assist in mixing of the gas and the liquid, said open cell foam having from about 3 to about 7 pores per inch and at least about 85 percent open volume;
- and
- a barrier coated on said open cell foam to reduce any mass transfer between the open cell foam and the liquid and between the open cell foam and the gas.
A method of calibrating a sensor of the type having a flow-through passage, comprising the steps of:
- pumping a sterile liquid through an endless path which includes the flow-through passage;
- injecting a sterile gas into the path to create a partial pressure of the gas in the path;
- mixing the gas with the sterile liquid in the endless path to control the partial pressure of at least a component of said gas in the sterile liquid;
- said step of mixing including passing the gas and liquid through an open cell foam, the open cell foam having from about 3 to about 7 pores per inch and at least about 85 percent open volume, the open cell foam further comprising a barrier coated thereon to reduce any mass transfer between the open cell foam and the liquid and between the open cell foam and the gas;
- venting at least some of the gas from the endless path;
- and
- exposing the sensor to the sterile liquid having the controlled partial pressure of said component of said gas whereby the sensor can be calibrated.
Dependencies are inferred from the claim text.