Physical measurements

The latest publications in this offer are:

• April 27, 2026

  R2005 Reviewed

  Calibration and verification of liquid flowmeters

  This article deals with the different calibration and verification methods for liquid flowmeters. Measurement principles, reference output quantity models and associated uncertainties are presented for each one. A calibration uncertainty budget is given as an example for gravimetric and volumetric methods and for comparison with a standard flow meter. Good practices, influence parameters and expression of calibration results and associated uncertainties, required for good implementation of liquid flow meters calibrations, are also discussed.

• April 24, 2026

  R2055 Reviewed

  Leak detection

  What is sealing? Tightness is the quality of a closed enclosure that does not allow any fluid to pass through its walls. Obtaining and maintaining such a property is, in reality, a gradation of operations, and the hermeticity of an enclosure must be considered, even from a theoretical point of view, as illusory. A perfectly homogeneous structure can be permeated by gases, due to sorption and desorption at the solid's interfaces, and solution and diffusion within it. This complex process, known as permeation, varies greatly according to the nature of the elements involved. Gas permeation through metals, for example, is not usually likely to affect sealing, whereas gas permeation through elastomers can lead to ambiguities in leak detection.

• December 10, 2025

  R3050

  Meteorological Measurements - Sensors and representativeness

  Meteorological measurements aim to quantify the different quantities that characterize the physical and thermodynamic state of the atmosphere, such as wind, temperature, humidity, solar radiation. Meteorological measurements can have various purposes, which condition the exposure of the sensors, a major factor for their representativeness.This article focuses on detailing each of these quantities (definitions, types of measurements carried out, influencing factors and exposure rules), mainly for in-situ measurements.

• September 10, 2025

  R3049

  The measurement of relative humidity in a climatic environment - The main types of hygrometer for measuring or determining relative humidity and associated uncertainty

  To make the right choice of instruments, for measuring relative humidity is not easy, given the various technical specifications announced by hygrometer manufacturers, with an accuracy of around ±1% RH.This article presents the hygrometric parameters used to calculate relative humidity values, ​​from a temperature measurement and an associated hygrometric parameter, with the relationships between the different parameters.It presents the three main types of hygrometers (impedance variation, condensation, psychrometer) used for measuring or determining relative humidity, in climatic environments, and gives examples of calculation of uncertainty, in relative humidity, from measurements with a psychrometer and a condensation hygrometer, combined with a thermometer.

• September 10, 2025

  R2765

  Thermoelectric microprobes

  Technical developments, and in particular the miniaturization of sensors, have given rise to a new family of thermocouples: thermoelectric microprobes.This article provides an overview of these increasingly widespread measuring instruments, by presenting the different types of microthermocouples available, their manufacturing, their operating modes (with or without contact) and their characteristics. Specific calibration methods and sources of error for these new thermocouples are also discussed.

• July 10, 2025

  R2385

  Solid State Gas Sensor Technology

  Gas microsensors are of great industrial interest due to their small size, low consumption, low cost and therefore deployable in a distributed network. Semiconductor gas sensors, although having limited performance compared to analyzers, are among the most commercialized sensors along with electrochemical and optical sensors.This article covers the operation of these sensors, the main materials used (metal oxides) with their detection mechanism as well as the design, manufacturing, characterization and calibration techniques. Current avenues of research around electronic noses and associated perspectives are also discussed.

• June 10, 2025

  R2380

  Gas detectors. Explosimeter – toximeter – oxygenometer

  Gas detectors, whether they are called explosimeters, toximeters or oxygenometers, are mainly used to monitor the atmosphere. They are designed to trigger an alarm following a measurement when the atmosphere becomes dangerous (explosible, toxic, lack or excess of oxygen).This article begins by defining the concepts associated with these devices, in particular the danger thresholds. It then presents the principles of detection, their characteristics and influencing factors, and the choice criteria of the various devices.

• November 10, 2024

  R2050

  Vacuum measurement

  Vacuum is the term to describe the state of a gas which pressure or density is lower than that of the prevailing atmospheric pressure. The defined range that can thus be measured, providing that the traceability to the SI exists, is widely extended since it covers fourteen orders of magnitude.This article deals with reference methods used to establish the traceability to pressure standards and with the variety of instruments which allow to perform measurements from rough to ultra-high vacuum.

• October 10, 2024

  R2220

  Measurement of fluid flow by means of pressure differential devices inserted in circular cross-section conduits running full

  This article deals with the measurement of fluid flow by means of pressure differential devices inserted in circular cross-section conduits running full.The principle of measurement consists in creating a local restriction in the fluid flow within a pressurised flow, which generates a pressure difference within the fluid which is related to the mass flow. There are as many flowmeters based on this principle as there are mechanically possible implementations of this local restriction.The best known are diaphragms or orifice plates, venturis and nozzles. The strength of this measurement technology lies in the fact that it benefits from extensive international standardization documents and exhaustive feedbacks.

• October 4, 2024

  R2165 Reviewed

  Optical particle characterization in flows

  This paper reviews techniques for the optical characterization of the size, morphology, concentration, fluxes and refractive index of microscopic particles (drops, bubbles, particles and aggregates) in dilute flows and systems. They are classified according to the size range (from the nanometer to millimeter scale), the quantities measured simultaneously, the measurement principles used and the methods of obtaining statistics.These techniques include notably the phase Doppler interferometry, shadowgraph imaging, diffractometry at the rainbow angle and light extinction spectrometry.

Access to a comprehensive database of articles

Rely on the ultimate technical and scientific knowledge database