Cork insulation; a complete illustrated textbook on cork insulation ...

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CORK INSULATION
subject of investigation in the Department of Agriculture in connection
with the study of the preservation of the good condition
of perishables vi^hile in transit.
Apparatus and methods of investigation had to be developed
to obtain the necessary data. Gradually there has been evolved an
arrangement of electrical thermometers which can be installed not
only in appropriate locations in the car, but within the packages,
and even inside an orange, peach, chicken or fish. The wires from
these thermometers run out between the packings of the door,
and the terminals are permanently or temporarily attached to the
indicators installed in an accompanying caboose.
Fundamental Facts Established.
To <strong>complete</strong> this investigation will require years of detailed
study. Certain fundamental facts, however, have been established
and are outlined in this paper. For example, the distribution of
the cold air from the ice bunker throughout the car is vital to the
preservation of the lading. The circulation of the air is produced
and maintained by the difference in weight of warm and cold air.
The actual difTerence between the weight of a cubic foot of air at
65° F. (1.18 oz.) and 32° F. (1.27 oz.) is only 0.09 ozs. Experiments
with stationary precooling plants, cooled by ice or by ice
and salt, have shown that the best and most economical results
are obtained by hanging a basket of suitable ice capacity close to,
but actually free from the walls of the room, and closing off the
basket by an insulated bulkhead open about twelve inches, both at
the top and bottom, to permit entrance and exit of air. In this
way a large surface of ice is exposed to air contact and the air is
compelled to travel over the entire column of ice before it escapes.
The insulated bulkhead prevents the absorption of heat from the
commodity and from the car, varying in quantity according to the
distance from the ice. The bulkhead also facilitates a steady ascent
and progression of the warm air in the car toward the top of the
bunker. To further facilitate the distribution of cold air throughout
the space, floor racks four inches high have been installed.
Now let us see what practical results such a combination produces
when applied to a refrigerator car which is, in other respects,
of the usual type. Chart I* shows the average temperature in
three cars of oranges in the same train in transit between Los Angeles
and New York, each car containing 462 boxes of fruit. Car
"A" had the box bunker and open or slatted bulkhead so commonly
seen in present day refrigerators. The lading was placed directly on
the floor. Car "B" had a basket bunker, insulated solid bulkhead,
and a rack four inches off floor. Car "C" was of the same con-
struction as car "B" but the ice was mixed with nine per cent salt
•The study of fruits and vegetables is being conducted by the Bureau of Plant
Industry, under the supervision of Mr. H. J. Ramsey. I am indebted to him for the
data on oranges and also such other facts concerning the transportation of fruits
and vegetables as are brought out in this paper.