Manômetro Bourdon – Funcionamento, Vantagens, Aplicação

Bourdon Manometer – Functioning, Advantages, Application

June 26, 2024 Roberto Magalhães

The Bourdon manometer is used to measure pressure.

Bourdon tubes measure gauge pressure, relative to ambient atmospheric pressure, as opposed to absolute pressure; the vacuum is detected as a reverse movement. When the measured pressure is pulsing rapidly, such as when the pressure gauge is near a reciprocating pump, an orifice restriction in the connecting tube is often used to prevent unnecessary wear on the gears and provide an average reading; When the entire meter is subject to mechanical vibration, the entire case including the pointer and indicator card can be filled with oil or glycerin. Typical modern high-quality meters provide an accuracy of ±2% of range, and a special high-precision meter can be accurate to within 0.1% of full scale.

Basic Principle of Bourdon Tube Pressure Gauge: –

When an elastic transducer (in this case, a Bourdon tube) is subjected to pressure, it fails. This deflection is proportional to the pressure applied when calibrated.

The Bourdon pressure gauge uses the principle that a flat tube tends to change to a more circular cross-section when pressurized. Although this change in cross-section may be hardly noticeable, the displacement of the tube material is magnified by the formation of the tube into a C-shape or even a helix, so that the entire tube tends to straighten or unwind elastically. as it is pressurized.

Bourdon tube pressure gauge diagram:

Construction of the pressure gauge with Bourdon tube: –

The main part of this instrument is an elastic transducer, which is a Bourdon tube that is fixed and open at one end to receive the pressure you want to measure. The other end of the Bourdon tube is free and closed. The cross section of the Bourdon tube is elliptical. The Bourdon tube is bent to look like a circular arc. An adjustable link is attached to the free end of the Bourdon tube, which in turn is connected to a sector and pinion. A pointer is connected to the pinion shaft that moves along a calibrated pressure scale.

Bourdon tube operation: –

The pressure to be measured is connected to the fixed open end of the Bourdon tube. The applied pressure acts on the inner walls of the Bourdon tube. Due to the applied pressure, the Bourdon tube tends to change in cross section from elliptical to circular. This tends to straighten the Bourdon tube, causing a displacement of the free end of the Bourdon tube.
This displacement of the free and closed end of the Bourdon tube is proportional to the applied pressure. As the free end of the Bourdon tube is connected to a link – section – pinion arrangement, the displacement is amplified and converted into a rotary movement of the pinion. As the pinion rotates, it causes the pointer to assume a new position on a calibrated pressure scale to directly indicate the applied pressure. Since the pressure in the box containing the Bourdon tube is generally atmospheric, the pointer indicates the gauge pressure.

Applications of Bourdon Pressure Gauge: –

They are used to measure medium to very high pressures.
To measure high pressures, for example in steam boilers, compressors.
To measure pressures in vehicle tube tires.

Advantages of the Bourdon pressure gauge: –

These Bourdon tube pressure gauges provide accurate results.
The Bourdon tube costs low.
Bourdon tubes are of simple construction.
They can be modified to provide electrical outlets.
They are safe even for high pressure measurements.
Accuracy is high, especially at high pressures.

Disadvantages of Bourdon pressure gauge: –

They respond slowly to pressure changes
They are subject to hysteresis.
They are sensitive to shocks and vibrations.
Amplification is mandatory as the displacement of the free end of the Bourdon tube is low.