Many of the following technical specifications appear on datasheets for pressure transducers and similar devices. Here we review their technical definitions and relationships.

**Root Sum Squares (RSS): **accuracy of a pressure transducer is calculated by taking the square root of non-linearity + hysteresis + non-repeatability.

For Example:

[Non-Linearity: (±0.1%)^{2} = 0.01%] + [Hysteresis: (±0.05%)^{2} = 0.0025%] + [Non-Repeatability: (±0.02%)^{2} = 0.0004%] = 0.0129%

√0.0129% = ±0 .11% FS at constant temperature

**Non-Linearity**

The relationship of a calibration curve to a specified straight line.

**Hysteresis**

The maximum difference in output at any pressure value within the specified range, when the value is approached with increasing and decreasing pressure.

**Non-Repeatability**

The ability of a transducer to reproduce output readings when the same pressure value is applied to it consecutively, under the same conditions, and in the same direction.

**Long-Term Stability**

The ability of a transducer to reproduce output readings obtained during its original calibration at room conditions for a specified period of time.

**Zero Offset**

Zero output is factory set to within a certain % of full scale. Results in a shift up or down of the calibration curve.

Does not affect linearity or accuracy.

**Span Offset**

Span output is factory set to within a certain % of full scale. Results in a change in the slope of the curve.

Does not affect linearity or accuracy.

**Thermal Effects**

The change in the zero and span output that occurs due to temperature changes.

Thermal Zero Shift: < +/- 0.004%/°F (0.0072%/°C)

Thermal Span Shift: < +/-0.003%/°F ( 0.0054%/°C)

Example: Temp Range -10°F to +130°F ( -23°C to +55°C)

Max temp. change from 70°F (21°C) = 80°F (44°C)

80°F X .004%/°F = .32% FS DZ/DT

or 44°C X .0072%/°C = .32% FS DZ/DT

80°F X .003%/°F = .24% FS DS/DT

or 44°C X .0054%/°C = .24% FS DS/DT

**CLICK HERE to learn more about how to calculate Total Error Band (TEB). **

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