There are many contributing error factors which go into a total uncertainty calculation and the proportion contributed by each one will be different from one measurement technology to another.
Specification Examples
Please click on an example term below to be guided to the associated glossary explanation:
Room Temperature Accuracy
- 0.25 % FS NLHR BSL
- 0.5 % FS TSL
- 0.25% FRO
- 0.2% URL
- 0.05% of rdg from 10 to 100% FS
- 0.15% Rdg + 0.15% FS + 1 digit resolution
- 0.02% full span hysteresis
- 0.01% full scale non-repeatability
- 0.025% full span non-linearity
- 0.35% FSO NLH BSL
Zero and Span Setting
- 0.02mA zero offset
- 3% FS span offset
- 2 mbar zero and span offset
Thermal Errors
- 1% FS TEB, compensated temperature range -20 to +80 degC
- 0.5% FRO RTE @ 23degC, from -10 to +50 degC
- 0.005 % FS / deg C TZS, over -20 to +80 degC
- 0.005 % span / deg C TSS, comp temp range -20 to +80 degC
Stability
- 0.01 % FS drift / year
- Zero stability of +/-0.1% FRO per annum
- Span drift of +/-0.05% rdg per year
Total Error Band
Glossary
Accuracy
How close the measured reading is to a reference point or value.
BSL - Best Straight Line
A virtual line derived from a set of non-linear points which is used to demonstrate the best accuracy that can be achieved from the product.
Drift
See stability.
FRO - Full Range Output
The difference in output signal between the minimum and maximum measurable pressure. Another way of describing the full scale for pressure sensors.
FS - Full Scale / Full Span
The difference between the lowest and highest measured point.
FSO - Full Scale Output
See full range output.
Hysteresis
The shift in measurement when comparing between readings of the same pressure which were taken following an increase in pressure and a decrease in pressure.
Linearity
The straightness of a set of measured points compared to a perfectly straight line.
Long Term Drift
See stability.
Long Term Repeatability
The amount of change in measured points following many measurement cycles from low to high, then to low again over a long period of time.
Long Term Stability
See stability.
NLH - Non-Linearity and Hysteresis
An accuracy or precision specification that only considers one cycle of increasing and decreasing pressure and excludes any short term repeatability effects.
NLHR - Non-Linearity, Hysteresis and Repeatability
An accuracy or precision specification that includes all room temperature uncertainties for a pressure sensing device. Occasionally may include zero and span setting offsets.
Non-Linearity
See linearity.
Non-Repeatability
See repeatability.
Precision
A measure of the proximity of all measured pressure points to a virtual reference line such as bsl or tsl.
Range
Defines the limits of variation in measurement, i.e. 100% span
RDG - Reading
Used to distinguish a percentage accuracy which varies proportionally to the measured span (% of reading) from one which is a fixed percentage of the maximum measurement reading (i.e. % of full scale).
Referred Temperature Error
A fixed temperature reference is defined (usually room temperature) which is representative of the average operating temperature. The temperature error is then defined as a +/- value of the largest error.
Repeatability
The amount of change in measured points following a number of measurement cycles from low to high, then to low again over a period of time.
Resolution
The ability of a device to distinguish a measurement via a reading or an signal output. In most cases the resolution should be much better than the overall accuracy, but in some cases the resolution can become a significant part of the total measurement uncertainty.
Short Term Repeatability
The amount of change in measured points following a few measurement cycles from low to high, then to low again over a short period of time.
Span
The difference between any measured point and the lowest value.
Span Offset
The variation in the span either represented as a percentage, pressure unit or output value error.
Span Stability
The amount of long term measurement variation which is only attributed to the span.
Span Drift
See span stability.
Stability
The amount of measurement change expected over a long period of time.
TEB (i) - Thermal / Temperature Error Band
The difference between the most negative and positive error across the whole temperature range. The difference is then halved and expressed as a +/- error.
TEB (ii) - Total Error Band
A combined error that includes linearity, hysteresis, repeatability, zero setting, span setting and thermal errors. It may also include stability error if a time factor is included with the total error band.
TSL - Terminal Straight Line
The line created by joining the lowest and highest measured points together. The error of all other measured points is referred to this line
TSS - Thermal / Temperature Span Sensitivity
How a measured value at any point in the range is affected by changes in temperature, normally expressed as a % span or % span / degC.
TZS - Thermal / Temperature Zero Shift
How much the lowest measured reading will vary with temperature, typically shown as % full span or % full span / degC.
URL - Upper Range Limit
Used to define the accuracy as a factor of the maximum range of a rangeable device rather than an adjusted (turndown) range.
Zero Drift
See zero stability.
Zero Offset
The amount of variation of the lowest measured reading for any one example of the same product type.
Zero Stability
The amount of long term measurement variation which only affects the zero offset.
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