Vakuumgauge

Vakuumgauge, or vacuum gauge, is an instrument used to measure the pressure inside a vacuum system. It provides a quantitative indication of how close the environment is to a perfect vacuum and is essential for processes that require controlled low-pressure conditions. Readings are commonly expressed in pascals, torr, or millibars.

Vacuum gauges operate on different physical principles and cover broad pressure ranges, from near atmospheric pressure to ultra-high vacuum. Some gauges infer pressure from a property that changes with gas density, while others rely on ionization or mechanical sensing. No single device spans the entire vacuum range with uniform accuracy; multiple gauges are often installed to monitor different bands of the spectrum within a system.

Common types include Pirani and thermocouple gauges, which measure thermal conductivity or thermoelectric response of the gas; McLeod gauge, which uses Boyle’s law on a compressed gas volume to determine very low pressures; and ionization gauges, which measure ion current produced by ionizing gas molecules in an electric field. Ion gauges are typically categorized as hot cathode or cold cathode; Bayard–Alpert and Penning variants are widely used for high and ultra-high vacuum.

Capacitance manometers use a deflecting flexible diaphragm with a capacitive sensor to provide accurate measurements in the higher end of the vacuum range and into near-atmospheric pressures. Practical use requires calibration for the gas composition and awareness of outgassing, gas dependence, and potential effects from contamination or high-voltage operation.

See also: Vacuum technology, Pressure measurement, Gauge calibration.