Vacuum Measurement and Control

 Rough Vacuum Gauges 1000 - < 1 mbar

 Fine Vacuum Gauges 1 - 10^-3 mbar

 Multi-Range and High Vacuum Gauges

 Vacuum Controllers 1100 to 1 mbar

The total range of scientifically useful vacuum extends from approx. 1000 mbar
(atmospheric pressure) down to 10^-12 mbar, the ultra high vacuum range.
The instruments for measuring the pressure are vacuum gauges.
No one physical measuring technique covers the whole vacuum/pressure range.
Particular sensors and gauges must be used for parts of the whole range,
rough, fine, high and ultra high vacuum.
These systems are also offered in combination as multi-range vacuum gauges for
covering multiple measuring ranges.

Rough vacuum gauges
Measuring range: atmospheric to 1 mbar
Besides the traditional vacuum gauges with mechanical sensors (e.g. Bourdon,
capsule gauge) diaphragm manometers with electronical diaphragm sensors are
well established (Piezo and capacitance gauges).
The pressure to be measured is separated by a diaphragm from a reference
vacuum and compared to the latter. The movement of the diaphragm is registered
either by a piezo resistive system or the diaphragm is part of a capacitor
(capacitance vacuum system). For improved chemical resistance the diaphragm is
often made of aluminium oxide ceramic.
The pressure measurement is independent of the type of gas.

Fine vacuum gauges
Measuring range: 1 mbar to approx. 10^-3 mbar
The method is based on the thermal conductivity of gases. The gauges are also
known as Pirani instruments. The heated filament within the gauge head forms
one part of a controlled Wheatstone bridge. The required energy for heating
the filament depends on the pressure and therefore is a measure of the
pressure.
The pressure measurement is dependent on the type of gas.

Multi range- and High vacuum gauges
Measuring range:  2000 to 6 x 10^-10 mbar.
Piezo, CAP, micropirani, combi, hot and cold cathode sensors are used in this
range. They work according to various measuring principles.
The measuring principles which vacuum gauges use for the high vacuum range
mainly depend on the type of gas involved.

The selection of the right vacuum gauge depends not only on the measuring
range but also on the operating conditions such as mechanical vibrations,
chemical contaminations and accuracy required.

The wide range of ILMVAC vacuum gauges covers the different pressure ranges
and applications. Some instruments can also be used as controllers due to the
intelligent integrated electronics.