Today in 1941, US Patent 2253940 A was issued, an invention of Gerald D. Peet, for his “Brew Cooling Equipment.” There’s no Abstract, although in the description it includes these claims:

The present invention is concerned with the art of cooling brew within the original shipping and storage package, by the circulation of cooling fluid through hollow structures in heat conductive relation with the brew contents.

As conducive to a clear understanding of the invention, it is noted that in the practical operation of brew cooling and dispensing systems of a it would be sufficient, however, to keep the contents of the kegs on reserve at ‘a temperature well above dispensing temperature and yet sufficiently cool to prevent deterioration. An arrangement which would impart such lesser degree of refrigeration to the contents of the kegs on reserve would bring about economy in power consumption and in the capacity of the refrigerating installation when it is attempted to direct the cooling fluid through cooling passages of constant area, the desired economy is not readily attainable because it is the magnitude of the cooling conduit area submerged in the brew which primarily determines the temperature to which the brew is cooled, assuming that an adequate supply of refrigeration is available, as it is in practice.

Viewed from the aspect of the keg structure per se, rather than as a system and method of operation, it is noted that the cooling instrumentalities which engage the contents of brew kegs of the internally cooled type require periodic inspection to assure their operative and sanitary condition.

For convenience and economy, it is therefore an important object so to construct and arrange such coolers as to facilitate removal thereof from the keg structures for such inspection and for repair and re-installation or replacement as the case may be, and that without bling or breaking down the kegs.