Referenstrycket

Referenstrycket is a baseline pressure used as a reference point in measurement, calibration, and theoretical calculations. By establishing a defined reference pressure, scientists and engineers can express other pressures as relative quantities and compare results across instruments and experiments. The choice of referenstrycket depends on the context: it may be a fixed standard value or the ambient atmospheric pressure at the location of measurement.

In thermodynamics, the term P° or referenstrycket is often set to 1 bar (100 kPa). Standard-state properties such as Gibbs energy, enthalpy, and entropy are tabulated at this pressure and a specified temperature (often 298 K).

In many practical contexts, pressures are measured as gauge pressure, defined relative to atmospheric pressure. Here, referenstrycket can effectively be the local atmospheric pressure, so that absolute pressure equals gauge pressure plus the reference pressure: P_abs = P_gauge + P_atm. Other contexts use 1 bar as the reference for calibration and comparison, bridging to the standard-state convention.

Usage and importance: Using a defined referenstrycket allows consistent data comparison between laboratories, instruments, and literature. The term is used in multiple fields, including chemistry, physics, meteorology, and mechanical engineering, with slight variations in exact value and terminology.