Measurement Mode

Gauge Pressure is the measurement of pressure relative to local atmospheric pressure. This is the most practical method, but since atmospheric pressure varies, it may have limitations in certain processes.

Absolute Pressure is the measurement of pressure based on true zero, or full vacuum, as found in the absence of matter, as in outer space. This is the pressure of physics, for example boiling point is determined by absolute pressure.

Differential Pressure is the measurement of one pressure relative to another pressure. Gauge Pressure is a specific form of Differential Pressure. Differential Pressure instruments are often needed when a small difference exists between two large pressures, when the allowable errors in measuring the static pressure are significant compared to the pressure difference.

Vacuum is the name given to gauge pressures below atmospheric pressure.

Compound Ranges are gauge pressure ranges which cover both vacuum and positive gauge pressures