Often you will see a measurement of vacuum pressure described as an absolute pressure reading, so is there any difference between the two?
A vacuum pressure is one that is lower than the ambient environment surrounding pressure, and is typically measured relative to a perfect vacuum or full vacuum.
Since the reference pressure is not relative to another pressure and does not change, it is called the absolute reference or absolute pressure reference.
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Any pressure measured relative to a full vacuum, whether above or below the surrounding ambient air pressure, is called an absolute pressure.
A vacuum pressure can always be measured and defined as an absolute pressure, but an absolute pressure can also be used to define pressures outside the vacuum range.

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Related Technical Terms
- Absolute Pressure
- Barometric Pressure
- MSL – Mean Sea Level
- Negative Gauge Pressure
- Reference Pressure
- Suction Pressure
- Vacuum