Types of Pressure Measurements

Learn about the seven different types of pressure measurements

1. TYPES OF Pressure Measurements

2. The relationships between gauge and absolute pressure are critical 2 Pressure Line 0 PSIA 14.7 PSIA 100 PSIA 114.7 PSIA Vacuum Range 14.7 PSIV -1 ATM 0 “ Hg mB / hPa Torr A 0 PSIV ATM 29.92 "Hg 1013 mB / hPa 760 Torr A Atmospheric Pressure -14.7 PSIG 0 PSIG 85.3 PSIG 100 PSIG 85.3 PSIC

3. Absolute Pressure Definition : Pressure measured relative to full vacuum (refers to a true zero reference) Units of Measure : Pounds per square inch absolute or (PSIA) Applications: best used in applications that require higher accuracies over large temperature range or for comparative studies at different elevations

4. Atmospheric Pressure Definition : Pressure of the atmosphere at the earth’s surface. At sea level this pressure is not constant (it varies with the weather) but averages around 100 kilopascals ( kP ). One atmosphere is also approximately the ambient pressure at sea level and is equal to 14.7 PSIA Units of Measure: pounds per square inch ( psi), atmospheres ( atm ), mb , hPa can measure ambient pressure in other circumstances Applications: remote weather stations, test stand reference pressure

5. Barometric Pressure Definition : The measure of atmospheric pressure Units of Measure: Often measured in millibars , in Hg (inches of mercury), or hector pascals I n other circumstances ambient pressure may be measured in pounds per square inch (PSIA) Applications : airports, AWOS systems, humidity measurements, data buoys

6. Compound Pressure Definition : P ressure measured from full vacuum (-14.7 PSIV) through atmospheric pressure to a positive gauge pressure, being referenced to current atmospheric pressure Units of Measure: pounds per square inch compound (PSIC) Applications: autoclaves, instrument sterilization, pumps

7. Differential Pressure Definition : Pressure measured relative from one pressure to another Units of Measure: pounds per square inch differential or (PSID) Applications: filter status, static pressure, chillers, sealed tank

8. Gauge Pressure Definition : A form of atmospheric pressure measured relative to ambient atmospheric pressure Units of Measure: pounds per square inch (PSIG) Applications: measuring pressure in vented tank (link to app note), pumps, compressors, test stands

9. Vacuum Pressure Definition : Generally refers to pressures below atmospheric pressure Units of Measure: pounds per square inch vacuum (PSIV) or 0-30”Hg Applications: semiconductor fabs , plasma sterilizers, vacuum packaging