Basic of calibration

To find a measure of best quality and quantity, process control is required. The value must be obtained from the gauge mounted on the process. Instrument must be accurate. Measure requires some setting of variables such as: range, zero, span, variable settings are needed to detect, manage and control the error, linearity, accuracy.
1. Process Variables
Process variable is the amount of physical or chemical quantities because of the influence of the process. Pressure, temperature, flow and level is the physical variables, whereas the oxygen content and pH values are chemical variables.
2. Range
Range is the boundary between the lowest value to highest value. For example, a physical variable of a process of value between 3 to 10 bars then, instruments used must have the highest value and the ability to measure the indicator value above 10 bar and the lowest value of 3 bars
3. Zero
Zero shows the lowest signal from the input or output and does not interpret the value of 0 (nil). A transmitter with the input range = 0 to 10 bar, output = 4 to 20 ma. So 4ma output value and input value is 0 bar zero value.
4. "Span"
The difference between the lowest and highest value is called "span", 0 to 10 bar has a value of span = 10 bar. 4 to 20mA has a span value = 16.
5. Error
The difference with the actual process value indication value measure is the actual process error.Ketika value and 5 bar gauge shows the mean error 5.2bar = 0.2bar
6. Linearity
In full-scale output than the input point as a point of readability measurement Linearity
input and output 0% 0%
input and output 25% 25%
input and output 50% 50%
input and output 75% 85%
input and output 100% 100% then the instrument is said to be non-linear
7. Accuracy
Measurement error value of the real value of the scala a full percentage accuracy values describing a tool ukur.contoh 1%, 2% is usually written on the gauge