The Bourdon Tube of a steam pressure gauge _______________ .

The Bourdon Tube of a steam pressure gauge is designed to measure pressure through the deformation of a curved tube. When pressure is applied, the tube tends to straighten out, and this movement is mechanically amplified to drive a pointer on the gauge dial.

In certain applications, particularly where steam or high-temperature fluids are present, the gauge requires protection to maintain accuracy and prolong its life. A loop seal serves this purpose by preventing the fluid from reaching the Bourdon Tube. This is especially important in environments with high thermal conductivity, where the steam could potentially cause rapid temperature fluctuations that might mislead the gauge's reading or damage the internal components. Thus, the use of a loop seal is essential to ensure consistent and reliable operation of the pressure gauge under varying conditions.

The other options do not accurately describe the characteristics of a Bourdon Tube used in steam pressure gauges. For example, connection to a digital display would imply a different technology altogether, while being made entirely of glass is impractical for durability and safety in high-pressure environments. Operating without a liquid filling is also misleading, as some gauges do benefit from liquid filling to dampen vibrations and reduce wear on the mechanical components. Therefore, the proper protection mechanism for a Bourdon Tube when handling steam is the loop seal