Calibration Technology

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Calibration Technology:  Basics, reference instruments for pressure and temperature, professional calibration

Introduction

Calibration Technology 

    Every measuring instrument is subject to ageing as a result of mechanical, chemical or thermal stress and thus delivers measured values that change over time. This cannot be prevented, but it can be detected in good time by calibration.

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The Egyptians already knew this almost 5000 years ago. The workers calibrated their yardsticks by comparing them with a “royal cubit” (approx. 52.36 cm) made of stone and thus managed to achieve, for example, side lengths on the Cheops pyramid of 230.33 m which differ from each other by only about 0.05 percent.

In the process of calibration, the displayed value of the measuring instrument is compared with the measuring result of a different measuring device which is known to function correctly and accurately and which itself has been made to coincide directly or indirectly with a national (or international) reference instrument

Valves, Piping and Pipelines Handbook

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Table Of Contents

Introduction 4

Traceability and calibration hierarchy 7

Calibration on an international level

National metrological institutes

Accredited calibration laboratories

In-house calibration

Professional calibration 12

Standards, regulations and calibration directives

Calibration capability

Ambient conditions

Calibration sequences

Reference instruments 25

Reference standards

Working standards

Portable pressure calibration instruments

Calibration characteristics 49

Measuring deviation

Hysteresis

Repeatability

Determination of the characteristics in practice

Measurement uncertainty 55

Basics according to GUM

Measurement uncertainty budget

Example calculation

Documentation 62

Minimum data required for a DKD calibration certificate

Graphic evaluation

Single-figure indication

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