SM0486
b. It is important to understand that hysteresis differs from
friction in that when hysteresis is present in a gage it cannot be eliminated.
This condition will cause the indication to read high on decreasing pressure.
Hysteresis is a function of elastic chamber repeatability.
c. Since there is no mechanical correction which can be made, the
only solution is to make a correction chart and attach it to the gage. In this way
the user can make mental and visual corrections as necessary.
(3) Range error.
a. As shown in Figure 9, range error is the pointer error of
increasing, or decreasing, magnitude which is compounded as the pointer traverses
the scale from zero to maximum scale indication.
At maximum applied scale
pressure, this condition causes the pointer to read short of maximum indication if
the spring is strong, or over maximum indication if the spring is weak.
Range
error is a function of the distance between the center of the arbor (sector pivot
point) and the centerline of the linkage, which connects the spring with the
sector.
Figure 9.
Range error-dial example
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