Pressure measurement is essential in various industrial and scientific applications, helping monitor and control processes accurately. Different types of pressure—such as absolute, gauge, and differential—are measured based on specific reference points like vacuum or atmospheric pressure.
Total Vacuum:
It is a state of zero pressure or lack of pressure, like what is experienced in outer space.
Vacuum:
This term refers to pressure measurements that compare total vacuum and normal atmospheric pressure.
Atmospheric Pressure:
- The pressure experienced on Earth’s surface due to the weight of atmospheric gases. It is usually measured at sea level as 14.7 psi or 101.36 kPa.
- Atmospheric pressure varies depending on altitude and weather conditions. For example, it drops to around 12.2 psi (84.12 kPa) at 5,000 feet above sea level.
- Absolute Pressure:
This type of pressure measurement is made relative to a vacuum, denoted in pounds per square inch absolute (psig). - Gauge Pressure:
Gauge pressure is measured relative to atmospheric pressure and is often expressed in pounds per square inch gauge (psig). It shows the relationship between atmospheric, gauge, and absolute pressures. - Differential Pressure:
It measures the difference between two points in a pressure or flow system. It is denoted by symbols like delta p (Δp).
