SM0486
manufactured.
It also establishes a series of
standard
case
sizes,
mounting
dimensions, ranges, dial appearance, etc.
(2) The terms "accuracy" and "error in indication" are frequently used in
the definitions of the three grade classifications. At this point, therefore, let
us define these terms.
(3) "Accuracy" is the quality of exactness or correctness in the pressure
indication. It is measured and graded by the amount of degree of error between the
indicated pressure and the true pressure acting on the gage. For example, suppose
a gage has a range of 0 to 500 psig and actually indicated 260 psig when you apply
a true pressure of 250 psig.
(4) The "error" in pressure indication is plus 10 psig, and the accuracy,
expressed in percent of full scale (range of the gage), is calculated as follows:
(5) If the indication of the gage is 240 psig when a true pressure of 250
psig is applied, the error in pressure indication is minus 10 psig and the accuracy
is -2 percent.
c. Now lets turn our attention to the classification of gages. During this
discussion refer often to Figure 7, which graphically illustrates the A.S.A.
accuracies.
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