Application range of Bourdon tube pressure gauges: for which range are Bourdon gauges typically used most effectively (units: kg/cm²)?

Introduction / Context:
Bourdon tube gauges are rugged mechanical devices that convert elastic deformation of a curved tube into pointer motion, widely used in plants for medium to high pressures. Understanding their preferred operating range supports correct instrument selection and accuracy expectations.

Given Data / Assumptions:

• Units expressed as kg/cm²; “gauge” means relative to atmosphere.
• Typical industrial Bourdon gauge with C-type or helical tube.

Concept / Approach:
Bourdon gauges excel at moderate-to-high positive pressures and can be built for very high ranges. Accuracy and resolution are better when the working pressure is in the mid-scale region. While compound Bourdon gauges can indicate vacuum, specialized devices (e.g., McLeod, Pirani, capacitance manometers) provide better accuracy at low or vacuum pressures. Therefore, the classic textbook selection highlights Bourdon gauges for pressures greater than a few kg/cm² (gauge), here represented as > 2 kg/cm² (gauge).

Step-by-Step Solution:
Match device characteristics (elastic tube) to pressure magnitude.Note limited sensitivity at very low pressures or vacuum.Select the option indicating > 2 kg/cm² (gauge).

Verification / Alternative check:
Vendor catalogs show spans from a few to thousands of kPa; accuracy classes (EN 837) emphasize best performance in mid-to-high spans.

Why Other Options Are Wrong:
Below atmospheric/very low gauge: Sensitivity and accuracy are limited.Absolute notation in option d is not the typical Bourdon gauge spec.“Exactly atmospheric”: Not a pressure range.

Common Pitfalls:
Using a high-range Bourdon to read tiny pressure changes results in poor resolution; select an appropriate range to keep normal operation near mid-scale.

Final Answer:
> 2 kg/cm² (gauge)