TOLERANCES IN U. S. STANDARDS 
Early in the development of U.S. standards as a basis for wholesale trading, 
it was found necessary to provide suitable tolerances in the various grades in 
order to allow for variations incident to proper grading and handling. Persons 
inexperienced in the application of standards often question the need for 
tolerances. To appreciate the necessity for them, however, such persons need 
only to visit a packing shed where any product is being graded and packed for 
shipment. 
In any commercial preparation for market operation it is necessary that sort- 
ing and packing be done rapidly in order to hold costs toa minimum. Certain 
types of products, such as apples, peaches, citrus fruits, and onions, usually 
are passed over movable conveyor belts, and defective specimens are womored 
by sorters as they move along on the belts (fig. 2). Under such a system, it 
is not humanly possible for employees to see all defects in specimens, especially 
those which are not plainly visible, such as very small worm holes in apples 
or peaches. Consequently, a few defective specimens naturally go into the 
packed containers and unless reasonable tolerances are provided in the grades, 
products would rarely, if ever, meet grade requirements. 
Figure 2.—Sorters grade oranges on Seale conveyor belts in a Florida packing house. 
The percentage of tolerances provided in grades for specimens failing to 
meet grade requirements varies with the different products, usually from 5 to 
ro percent. The latter tolerance is the most prevalent. However, serious 
defects resulting from freezing injury and soft rot which may develop further 
and spread to other specimens, are usually restricted to 1 or 2 percent. Where 
a total tolerance of 10 percent is allowed in certain grades, often: this total is 
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