High accuracy pressure instruments with precise sensor technology & digital electronics for test, research & calibration applications.

# Accuracy

Accuracy performance and measurement error guides & explanations

## Hysteresis

Hysteresis is the difference of two separate measurements taken at the same point, before and after a physical quantity is increased and decreased.

## g Effect

The g Effect is a change in performance of a pressure measuring device that is caused by a change in its orientation. Typically a pressure sensing device will have some form of flat diaphragm which will generate a change in output when flexed by a change in pressure. If a pressure sensing diaphragm is orientated […]

## PPM – Parts Per Million

Parts Per Million (PPM) is a ratio used to describe the maximum measurement error or resolution of pressure measurement equipment.

## LHR – Linearity, Hysteresis and Repeatability

Linearity, Hysteresis and Repeatability (LHR) is often used to describe the room temperature precision of a pressure sensor, excluding all zero & span offsets, temperature errors and long term stability. Also see non-linearity and pressure hysteresis.

## Secondary Pressure Standard

Secondary Pressure Standards are pressure calibration instruments which have to be checked by primary pressure standards on a regular basis.

## Threshold

Threshold is the amount of measurement change required before a measuring instrument reacts with a change in measurement output or produces a specified result.

## TSS – Thermal Span or Sensitivity Shift

Thermal Span or Sensitivity Shift signifies the maximum amount of span that will change at any measurement point within the compensated temperature range.

## TEB – Total Error Band

Total Error Band (TEB) is the difference between the most negative and most positive deviation from the true measurement, determined from the combination of all known errors for a sensing device, within the constraints of the measurement and operating temperature range. Typically in the case of a pressure measurement device for example, the total error […]

## TZS – Thermal Zero Shift

Thermal Zero Shift (TZS) is the maximum amount the output or reading at the null measurement point might deviate over the compensated temperature range

## Thermal Hysteresis

Thermal Hysteresis is the measured change in output or reading at a specific measurement point taken during a sequence of increasing and decreasing temperature.

## TSL – Terminal Straight Line

Terminal Straight Line (TSL) is a straight line drawn between the measurement output at zero and at full scale.

## TEB – Temperature Error Band

Temperature Error Band (TEB) is the error derived from the most positive and negative deviation of all measurement points within a measurement range over the operating or compensated temperature range.

## Temperature Error

Temperature Error is the deviation of a measurement reading caused by a change in media or environmental temperature.

## Temperature Compensation

Temperature Compensation is a correction applied to a measurement instrument to reduce errors attributed to temperature changes in a process media which is being measured or in the surrounding environment that the instrument is being used.

## Repeatability

Repeatability is the amount of change in a measured reading at the same measurement point after a defined number of cycles over the measurement range or a set of environmental limits.

## RTE – Referred Temperature Error

Referred Temperature Error is the max deviation expressed as a +/- %FS from measurements taken at a defined temperature.

## Accuracy

Accuracy of a measurement instrument defines how much a measurement value may deviate from the perfect measured value.

## Precision

Precision is the measure of how closely a set of readings will be to a reference line that passes through the middle of all the points.

## NL – Non-Linearity

Non-Linearity is the deviation error derived from the straightness of a set of recorded measurements when compared to a straight line, such as bsl or tsl, drawn through all the results. The maximum non-linearity error is normally expressed as a percentage of full scale.

## Long Term Stability/Drift

Long Term Stability or Long Term Drift is the amount of change of a measured reading at exactly the same pressure and ambient conditions over a given period of time which is typically quoted as an annual figure.

## Pressure Hysteresis

Pressure Hysteresis is the difference between two separate measurements taken at the same pressure but one where the pressure was increasing and the other where the pressure was decreasing. The hysteresis is caused by the natural reluctance of a pressure sensing material such as a diaphragm to return to its original position, shape or form […]

## Digital Compensation

Digital compensation is the process of correcting measurement signals using look up tables or mathematical formula.

## BSL – Best Straight Line

Beast straight line (BSL) is the mathematically derived straight line which runs through the middle of a set of readings in such a way to achieve the smallest error across all the results. The measurement precision of a device is often specified in relation to the maximum deviation from the best straight line.

## Measuring level of stoddard solvent in a sealed tank

We are trying to measure pressure in a gas tank filled with stoddard solvent.

## Compensated Temperature Range

The compensated temperature range defines the limits of operation for a specified measurement accuracy. e.g. A pressure sensor has an accuracy of 0.25% full scale over a compensated temperature range of -20 to +80 degC. Since temperature errors are often significant for many measurement devices, a manufacturer will incorporate digital or analogue temperature compensation. If the measurement device is […]

## Determining calibration error of Bourdon tube pressure gauge

How do you calculate maximum gauge error in pressure measurement with a bourdon gauge instrument?

## Ex logger for recording pressure up to 300 bar & temperature up to 40degC

I am looking to source a digital Ex data logger with the capacity to measure temperature from 0-40 degC and pressure from 0-200 barg

## Shunt resistor calibration explanation

What is the method of shunt calibration in relation to an indicator connected to a pressure transducer?

## Measuring a 125 mm of water level range to 1mm accuracy

We are looking to measure liquid level to an accuracy of 1mm over a range of around 125mm.

## Measurement Accuracy

There are many contributing error factors which go into a total uncertainty calculation. The way accuracy is defined for pressure instruments on technical data sheets can vary significantly across manufacturers and product types.

## What affects the performance of low pressure sensors

By their nature low range pressure sensors are very sensitive instruments and there a few factors that need to be considered prior to and during installation.

## How does the accuracy of pressure measurement devices change over time

Not even the most accurate pressure instruments will hold their accuracy indefinitely, all are prone to drift over time.

## Pressure Sensor Accuracy Specifications

Understand what parameters are included in pressure sensor accuracy specifications and what techniques were used, so that a true comparison can be made.

## Choosing calibrator for pressure transmitters

A guide on what to consider when choosing pressure calibration equipment for calibrating pressure transmitters.