Comparison of Diaphragm and Bourdon Tube Mechanisms in Pressure Gauges and Switches

Review and Comparison of MechanismsDiaphragm  و Bourdon Tube   In Pressure Gauges and Switches

In pressure measurement, the diaphragm and Bourdon tube mechanisms are commonly used. In some cases, bellows and capsule mechanisms are also employed, which function similarly to the diaphragm type.

Bourdon Tube Mechanism

The Bourdon tube is a hollow, oval-shaped metal tube. In its normal state, it is at its maximum curvature, and applied pressure causes it to straighten. In pressure gauges, this deformation is transmitted to the indicator via a gear mechanism, while in pressure switches, it actuates an electrical microswitch.

Advantages of the Mechanism Bourdon Tube :

Wide measurement range in terms of bar

Long service life

Lower cost

High accuracy (0.5 to 1 percent)

Disadvantages of the Mechanism Bourdon Tube :

Sensitivity to vibration, shock, and oscillation

Slow response time

Diaphragm Mechanism

In this case, the process pressure is applied to a flexible metal diaphragm, and the displacement of this diaphragm is transmitted via a metal linkage to move the pointer in pressure gauges or to actuate a microswitch in pressure switches.

Advantages of the Mechanism Diaphragm :

Smaller size

Suitable for viscous fluids and fluids with suspended particles

Capable of measuring millibar-level pressures

Disadvantages of the Mechanism Diaphragm:

Higher maintenance costs

Lower accuracy (1.6 to 2.5 percent)

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