Pressure Terminology & Definitions

Gauge Pressure: Pressure measured relative to ambient atmospheric pressure. Referred to as pounds per square inch (gauge) or psig.
 
Absolute Pressure: Pressure measured relative to high vacuum. Referred to as pounds per square inch (absolute) or psia.
 
Vacuum: Vacuum measured relative to ambient atmospheric pressure. Referred to as pounds per square inch (vacuum) or psiv, or inches of mercury (Hg) vacuum.
 
Differential Pressure: Pressure measured relative to a reference pressure. Referred to as pounds per square inch (differential) or psid.
 
Pressure Transducer: Provides a linear DC voltage output proportional to applied pressure.
 
Pressure Transmitter: Provides a linear current output proportional to applied pressure.
 
Proof Pressure: The maximum pressure that may be applied without physical damage to the sensing element.
 
Burst Pressure: The maximum pressure that may be applied without physical damage to the sensing element.
 
Accuracy: Combined error of linearity, hysteresis and repeatability.
 
Linearity: The maximum deviation of any calibration point, on a specified straight line, during any one calibration cycle.
 
Hysteresis: The maximum difference in output, at any measured value within the specified range, when the value is approached first when increasing and then decreasing pressure.
 
Repeatability: The ability to reproduce output readings when the same pressure value is applied consecutively, under the same conditions, and in the same direction.
 
Excitation: The external electrical voltage and/or current applied to a transducer for its proper operation.
 
Ambient Conditions: The conditions (pressure, ,temperature, etc.) of the medium surrounding the case of the transducer.
 
Response Time: The length of time required for the output to rise to a specified percentage of its final value as a result of a step change in pressure.
 
Thermal Error: The maximum change in output, at any pressure value within the specified range, when the temperature is changed from room temperature to specified temperature extremes.
 
Thermal Sensitivity Shift: The sensitivity shift due to changes of the ambient temperature from room temperature to the specified limits of the operating temperature range.
 
Thermal Zero Shift: The zero shift due to changes of the ambient temperature from room temperature to the specified limits of the operating temperature range.