When discussing a piping system, the term “pressure” is often used to describe a key fluid property that plays an important role in the operation of equipment like pumps, control valves, tanks and vessels and other devices. However, like many terms used in engineering, there are nuances in meaning that must be taken into account to avoid miscommunication, confusion and costly mistakes. Quite often, key qualifiers that distinguish between total pressure, static pressure and dynamic pressure are not used. Sometimes the distinction is important, just as the difference between mass flow rate and volumetric flow rate must be made to be concise when discussing flow rate.
Definition and Units
The classical definition of pressure is the amount of force acting on a surface per unit area, as shown in Figure 1.