Image Number 3 for United States Patent #4759848.
A cryogenic liquid is sterilized by passing it through a microporous filter, while subcooling the liquid. Subcooling virtually eliminates the possiblity of formation of gas bubbles in the liquid, and thereby insures that the desired mass flow of liquid, through the filter, will be maintained. The apparatus used with this invention comprises an insulated tank, filled with cryogenic liquid. A container having a microporous filter disposed therein, is submerged within the tank. The filter can be made of nylon mesh, which is encased within a polypropylene frame. The filter has a pore size of about 0.2 microns or less. The liquid to be sterilized is a saturated cryogenic liquid. The liquid in the tank is held at a temperature lower than that of the liquid to be sterilized, and therefore subcools the liquid being sterilized. The sterilized liquid is then withdrawn directly from the filter container.