Leybold Bourdon Needle Dial Vacuum Pressure Gauge With ISO-KF NW 16 Fitting
These Leybold Bourdon needle dial vacuum pressure gauges have a KF-16 inlet vacuum connection and can measure vacuum pressure in the 1 to 1020 mbar range.
Bourdon Dial Needle Vacuum Pressure Measurement Gauges, by Wikipedia.org
A Bourdon gauge uses a coiled tube, which, as it expands due to pressure increase causes a rotation of an arm connected to the tube.The pressure sensing element is a closed coiled tube connected to the chamber or pipe in which pressure is to be sensed. As the gauge pressure increases the tube will tend to uncoil, while a reduced gauge pressure will cause the tube to coil more tightly. This motion is transferred through a linkage to a gear train connected to an indicating needle. The needle is presented in front of a card face inscribed with the pressure indications associated with particular needle deflections. In a barometer, the Bourdon tube is sealed at both ends and the absolute pressure of the ambient atmosphere is sensed. The Bourdon pressure gauge measures pressure relative to atmospheric pressure, that is, they measure pressure directly relative to the surrounding atmospheric pressure.
