606 



U. 8. BUREAU OF FISHERIES 



with the fish. 75 A plant is in operation at Port Dover, Ontario, on 

 Lake Erie, with a daily capacity of from 12 to 20 tons of fish a day. 

 Shallow pans in shape and dimensions similar to the ordinary air- 

 freezing pans for Lake Erie fish, holding about 17^ pounds each, are 

 provided Avith lids somewhat deeper than the pans. The pan itself 

 has two V-shaped metal strips fastened to the bottom, so that when 

 the pans are stacked, one on another, they are separated by the thick- 

 ness of this strip to allow circulation of brine between. Twenty 

 such pans, after having been packed with 350 pounds of fish in 

 the ordinary manner of air freezers, are placed in a frame made of 

 angle irons. This frame is lifted by a traveling overhead electric 

 hoist, moved over the brine tank as in Petersen's method, and lowered 



Fig. 41. — Kolbe's method of freezing. Frame of pans being lowered into brine tank. 

 Courtesy, Kolbe Fish Co. 



into the brine. The tank contains 9.400 feet of l^-inch pipe and 

 15,000 gallons of calcium chloride brine, chilled by ammonia and kept 

 in motion by means of agitators. 



The brine is prevented from entering the cans by air entrapped 

 in each pan, as in the diving bell. The air entrapped is compressed 

 in direct proportion to the depth to which it is lowered, and in direct 

 proportion to the specific gravity of the brine. If, therefore, provi- 

 sion is made for a sufficient volume of air under the lid of each pan, 

 the pan may be immersed to a considerable depth before the brine 

 can reach the fish — hence a lid deeper than the pan. 



Refrigeration is furnished by a 9 by 9 inch inclosed compressor 

 driven by a 35-horsepower motor. When fish are not being frozen, 

 some refrigeration is accumulated by mushing the large volume of 

 brine. The brine, of course, may be chilled by pipes in the ice tank, 



75 U. S. Patent 1527562, Feb. 24. 1925. 



