Bourdon Tube Pressure Gauges and Their Applications

Types of Bourdon Tube Pressure Gauges

Over time, different shapes of the tube were developed to handle different pressure ranges and applications. The three main types are:

1. C-Type Bourdon Tube Pressure Gauge

• Has a C-shaped tube.
• Expands or contracts depending on pressure.
• Best for low to medium pressure measurement.
• This is the most common and widely used type.

Tip: If you see a standard pressure gauge in daily use, it is most likely a C-type Bourdon gauge.

2. Spiral-Type Bourdon Tube Pressure Gauge

• The tube is shaped like a spiral.
• Provides better sensitivity and accuracy than C-type.
• Mainly used for lower pressure ranges where fine accuracy is needed.

3. Helical-Type Bourdon Tube Pressure Gauge

• Has a helix (spring-like) shape.
• Can handle very high pressures safely.
• Offers increased accuracy and resists damage from overpressure.

Tip: Use spiral type for better accuracy at low pressure, and helical type when dealing with very high pressure.

Dry vs. Wet Bourdon Tube Pressure Gauges

Bourdon gauges are also classified as dry or liquid-filled (wet).

Dry Gauge

• No liquid inside the case.
• Works directly with the tube’s movement.
• Simple and cost-effective.
• Best for places with steady pressure and low vibration.

Wet (Liquid-Filled) Gauge

• Filled with glycerin or silicone oil.
• The liquid acts like a cushion, damping vibrations and pulsations.
• Gives more stable and accurate readings.
• Perfect for pumps, compressors, and heavy-duty machinery.

Tip: If your gauge is in a vibrating environment, always go for a liquid-filled Bourdon gauge. It will last longer and show steady readings.

Advantages of Bourdon Tube Pressure Gauges

1. Simple design – Easy to use, no skilled operator required.

2. Wide range – Can measure both low and very high pressures.

3. No electricity needed – Works mechanically.

4. Reliable accuracy – Suitable for real-time monitoring.

5. Affordable and long-lasting – Costs less than many modern gauges.

Disadvantages of Bourdon Tube Pressure Gauges

1. Sensitive to vibration and shocks – Especially in dry types.

2. Low displacement at tube end – Needs amplification for pointer movement.

3. Hysteresis effect – Small errors may occur when pressure increases and decreases repeatedly.

Tip: If accuracy is critical in vibrating conditions, use a liquid-filled gauge or go for electronic pressure transmitters.

Common Uses of Bourdon Tube Pressure Gauges

• Measuring pressure of gases and liquids in pipelines.
• Used in analog pressure meters.
• Widely applied in the petroleum, chemical, and power industries.
• Found in compressors, pumps, and hydraulic systems.

Construction of a Bourdon Tube Pressure Gauge

• Tube Shape: Usually C-shaped, but can also be spiral or helical.
• Fixed End: Connected to the pressure source.
• Free End: Moves slightly when pressure is applied.
• Linkage Mechanism: Transfers tube movement to the pointer.
• Pointer and Dial: Shows the pressure reading.

The tube’s cross-section is not round but elliptical. When pressure enters, the tube tends to become circular. This causes the tube to straighten, and the free end moves. The pointer mechanism magnifies this movement into a readable scale.

Tip: Even though the tube moves only about ⅛ inch, the clever linkage makes the pointer move across the entire dial!

Working Principle of Bourdon Tube Pressure Gauge

1. Pressure enters the tube.

2. The tube tries to straighten.

3. The free end of the tube moves.

4. A linkage converts this small movement into rotation.

5. The pointer shows the pressure on the dial.

That’s it! Very simple and effective.

Why Bourdon Tube Pressure Gauges Are Still Popular

Even after more than 170 years, Bourdon gauges are still widely used. Here’s why:

• Rugged and durable – Can last for years with minimal care.
• Wide measuring range – From very low to extremely high pressures (0.6 to 7,000 bar).
• Independent of power supply – Works even in remote areas without electricity.
• Proven technology – Trusted by industries worldwide.

Practical Tips for Using Bourdon Tube Pressure Gauges

• Always check the pressure range before using a gauge. Don’t exceed its limit.
• If the gauge will face pulsations, use a liquid-filled type.
• Install gauges vertically for best accuracy.
• Regular calibration ensures long-term accuracy.
• Avoid dropping or exposing gauges to sudden shocks.

Quick Tip: Never use a Bourdon gauge near strong vibrations without a damping system. Otherwise, the needle will keep dancing and give false readings.

So what we learn today?

The Bourdon Tube Pressure Gauge is a simple yet brilliant invention that changed how industries measure pressure. With just a curved tube, a pointer and a dial, it provides accurate readings without any electricity or complex systems.

• C-Type – simple, everyday use.
• Spiral-Type – more accuracy for low pressure.
• Helical-Type – strong and accurate for very high pressure.
• Dry vs. Wet – choose based on environment (steady vs. vibrating).

Whether in refineries, chemical plants, or power stations, you will still find these gauges working reliably. Their long history, low cost, and dependable performance make them a favorite choice across industries.

If you want a pressure gauge that is affordable, durable and does not need power: Bourdon tube pressure gauge is the answer.