High pressure - From 50 MPa to 2 GPa

High-pressure technologies are used in a wide range of industrial sectors: for example, the automotive industry with injection systems, the petrochemical, pharmaceutical and food industries, certain processes such as die-cutting, not forgetting military applications. The development of the high-pressure sensor market, with the appearance of new models for pressures in excess of 1 GPa, reflects the evolution of the sector and the growing need for measurement to meet ever-increasing performance demands.

The first paragraph introduces the various forms of pressure and the fluids that transmit it. The article is deliberately limited to static pressure, i.e. pressure that is stable or virtually stable over time. Dynamic pressure and its very specific aspects are the subject of another article in the series. After a reminder of the notion of metrological connection, the available instrumental techniques are analyzed.

In the following paragraphs, we describe the instruments used to measure and detect pressure, and then the instruments used to connect them to national and international standards, i.e. digital manometers, pressure calibrators and generator-measurers. Without repeating aspects already covered in other articles in the series, we develop the specific instruments for high pressures, focusing on their place in the calibration chain and their limits of use. Particular attention is paid to manganin gauges, measuring instruments that reach the limits of the swept pressure range. For each family of instruments, we provide information on how to optimize their use in terms of metrological performance. In particular, we introduce the main components to be taken into account in uncertainty budgets.

The pressure balance, which is the reference throughout the calibration chain and has many advantages in the high-pressure field, is the subject of paragraph 4 . The different types of balance and their place in the chain are described. Calibration techniques and the use of balances are discussed, after a detailed description of their operation. The pressure intensifier, an instrument derived from the balance, takes over for the highest pressures.