A parameter is a numerical variable that describes a physical quantity. Therefore, for a number to describe a physical quantity, it is necessary to describe what that physical unit is, in what units it is measured, and what type of amplitude it is.

Some examples of physical quantities and their units are:

• Volumetric flow (m3 / s, m3 / h, l / s, p3 / s).
• Current (A, mA).
• Pressure (Pa, psi, ba, mmHg).
• Temperature (ºC, ºF).
• Speed (m / s, m / h, mm / s, p / h).
• Rotation speed (RPM, rev / s).
• Volume (m3, p3, l, gal).