SIKA Bourdon Tube Pressure Gauges
Bourdon tube pressure gauges are equipped with a spring tube, also known as a Bourdon tube, which is fixed at one end. The medium to be measured flows through this tube. Since the outer surface of the Bourdon tube is larger than the inner surface, the force acting outwards is greater, thus causing the Bourdon tube to expand slightly as the pressure increases (similarly to a party blower). This deflection is transferred to the pointer by means of a linkage and gearing attached to the tip of the Bourdon tube.
Depending on the measuring range and the medium to be measured, Bourdon tubes can have different wall thicknesses, cross-sections (ranging from round to oval), shapes and materials. The pressure applied to the tube must not be too high (overload), as it will otherwise be permanently deformed and can then no longer provide accurate measurements.
Our Bourdon tube pressure gauges measure the relative pressure, i.e. the difference between the pressure inside the tube and the surrounding air pressure; the housing is vented. Changes to the ambient air pressure, e.g. due to changing weather or at great heights (above sea level) are not relevant to the measurement result or are within tolerance limits. In any case, when multiple devices are used in an application, the height already plays very little part in the process: A production facility will not generally be located at significantly different heights above sea level or in vastly different air pressure zones. This ensures the necessary comparability of the measurements.
If the devices are subjected to water hammer (e.g. when installed in a pump), an arrestor should be fitted between the pressure source and the measuring instrument in order to protect the Bourdon tube.
A filling in the housing protects against vibrations in the measuring system. Glycerine is usually used for this purpose.
The medium to be measured must not be too hot (a siphon or separator should be used where necessary) and under no circumstances must it freeze inside the Bourdon tube.
Bourdon tube pressure gauges are ideal for measuring the pressure of gaseous and liquid media but are not suitable for highly viscous or crystallising media. The choice of material for the measuring unit and process connection depends on the medium to be measured.
