Bourdon tube pressure gauges are one of the most common types of mechanical pressure gauges used for measuring gauge pressure. Here’s an overview of how they work and their key features:

1. Working Principle: Bourdon tube pressure gauges operate based on the principle that a curved tube tends to straighten when pressure is applied inside it. The Bourdon tube, typically C-shaped or helical in design, is connected to the process whose pressure is being measured. As pressure increases, the tube attempts to straighten out, and this movement is translated into rotational motion via a mechanical linkage.

2. Construction: Bourdon tubes are typically made of materials such as bronze, stainless steel, or other alloys with good elasticity and strength. The tube’s cross-section can vary, affecting its sensitivity and range. The free end of the Bourdon tube is connected to a gear mechanism that amplifies its movement, which is then displayed on the gauge dial.

3. Types of Bourdon Tubes:

   • C-Type Bourdon Tube: It resembles a C-shaped coil and is commonly used in gauges for lower pressure ranges.
   • Spiral or Helical Bourdon Tube: It is wound into a spiral or helix shape and is used in gauges for higher pressure ranges.
   • Coiled Tube: This type consists of a coiled Bourdon tube, offering increased sensitivity and accuracy.

4. Pressure Range and Scale: Bourdon tube pressure gauges are available in a wide range of pressure ratings, from vacuum to high pressure. The gauge dial is calibrated to indicate pressure readings in units such as psi (pounds per square inch), bar, kPa (kilopascal), or other appropriate units.

5. Accuracy and Sensitivity: Bourdon tube gauges typically offer good accuracy and sensitivity, with accuracy levels ranging from ±0.5% to ±1% of full scale. However, their accuracy can be affected by factors such as temperature variations and mechanical wear over time.

6. Applications: Bourdon tube pressure gauges find applications in various industries, including oil and gas, petrochemical, pharmaceutical, automotive, and manufacturing. They are suitable for measuring pressure in liquids, gases, and steam.

7. Maintenance: Regular calibration and inspection are essential to maintain the accuracy and reliability of Bourdon tube pressure gauges. Maintenance may involve checking for mechanical wear, ensuring proper zero adjustment, and recalibrating if necessary.

Overall, Bourdon tube pressure gauges offer a simple yet reliable method for measuring pressure in a wide range of industrial applications. They are robust, cost-effective, and well-suited for both portable and permanent installations.