1.1 Instrumentation terminology
1.1.1 Range: It is all the set values within the lowest and highest readings an instrument can measure reliably. For example, a thermometer whose scale goes from 0°C to 50°C has a range from 0°C to 50°C. We can also define it as the measured variable set values which are within the upper and lower limits of the instrument’s measure capacity.
1.1.2 Accuracy: It is the quality that an instrument has to give readings as close as possible from the measured magnitude’s true value. We can define it in other words as the degree of accordance from an indicated value according to a standard one, considering this last standard value as the true one. The independent degree of accordance is the maximum deviation among the calibration curve and a specific curve, so that this maximum deviation will be minimized.
1.1.3 Precision: It is the quality that an instrument has to give readings, which are really close between each other; their degree of dispersion. An instrument might have a poor level of accuracy but a great precision. Therefore, measure instruments will be designed by companies to be precise and readjustable to be accurate, due to their periodic decalibration.
1.1.4 Repeatability: It is the variation among the obtained measures with an instrument when it’s used several times by an operator / automatically, at the same time it measures the same characteristics in the same place. That is to say, it is the instrument’s output signal’s position reproduction capacity, while measuring a variable’s same values in the same service conditions and variation sense.
1.1.5 Hysteresis: Maximum difference appreciated in the values, indicated by the instruments indication or the output signal for the same value. The variable passes through the complete scale in both ways ascending and descending
1.1.6 Zero deletion: When the measured variable’s value of “zero” are within the field of measurement, that is to say, the number where the field’s lower value gets bigger than the variable’s zero value.
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1.1.7 Resolution: It is the least difference in the value an instrument can identify. The operator intervenes in analogical devices depending on the way they looks at the needle’s position, their parallax error when reading and the distance between the values marked on the scale, that means, how clear and exact can the value given by the instrument be read.
Dead zone: It is the variable's group of values that doesn't make the instrument indication or output signal change, that is to say, that produces no answer. It is given as a measure range percentage.
Reliability: It is the probability measure that an instrument still behaves within the specified error limits over a certain time and under specific conditions.
Traceability: Property of the measure’s result, made with an instrument or pattern, so that it can be related to national or international patterns with an uninterrupted chain of comparisons and every doubt solved.
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Noise: It is any electrical disturbance or any accidental unwanted signal which modifies data transmission, indication or record. An special case is RFI (radio frequency interference).