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Calibration · Glossary

What is Zero and Span Error?

offset and gain errorsCalibration

Zero and span error describe an instrument whose reading is offset at the bottom of the range (zero) or wrong in slope across the range (span).

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Zero and Span Error Explained

A zero error shifts every reading by the same amount. A span error grows from zero to its largest at full scale. Most calibrations correct zero first, then span, then recheck zero.

Static pressure, mounting position and temperature commonly shift the zero.

Zero and Span Error Formula

Reading = (1 + espan) × True + ezero
ezerooffset
espanrelative slope error
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Calculators for Zero and Span Error

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Frequently Asked Questions

What is Zero and Span Error?

Zero and span error describe an instrument whose reading is offset at the bottom of the range (zero) or wrong in slope across the range (span).

Why recheck zero after span?

On many instruments the adjustments interact.

What is a sensor trim?

A HART adjustment of the digital reading to the reference, separate from the 4 to 20 mA output trim.

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