Bourdon Barometer
The Bourdon sphygmomanometer, also known as the hand barometer, was invented in 1852. Bourdon sphygmomanometers have a larger measuring range than diaphragm and capsule sphygmomanometers and are commonly used to measure high pressures. Bourdon sphygmomanometer is one of the most widely used in the industry.
Bourdon tube is a twisting tube made of flexible metal in the shape of a cane with an angle of about 250 degrees. In the Bourdon tube, the end of the tube is blocked and its beginning is connected to the fluid reservoir being measured. When applying pressure, the Bourdon tube tends to straighten, which determines the change in position by adapting to the previous state of pressure under test. Changing the positions of the Bourdon tube moves the scorpions on the graded plate through a gear mechanism. These degrees, which are determined by the movement of the hand, are called the relative pressure of the fluid.
Types of Bourdon barometers
Barometer typeC(PipeC)(C-Tube):
The basis of this barometer is based on the basic design of the Bourdon barometer described above. PipeCThe shape is usually used inside other barometers as well. As you can see in the figure, when pressure is applied to one end, the other end tends outwards, which is transferred to a spring. To the movable tip of the tubeCOne interface bar and the other end are attached to the gear, which engages with another small gear attached to the hand. More precisely, by applying pressure to the Bourdon tube, the rod then moves the segmental gear, followed by the small gear and the hand on the plate.
From a more technical point of view, this instrument is a closed-ended tube that has an angle of about 250 degrees and when pressure is applied to it, it tends to protrude due to the difference in the pressure of the external and internal environment. The change in pipe position is proportional to the pressure being measured. The opening and closing of the tube is between 0.25 and 0.4 inches.
Circular tube barometer(Helical Tube):
This type of barometer consists of a hollow bar with a longitudinal step that is deformed by applying pressure. They use annular Bourdon tubes to measure high pressures up to 600 bar.
It should be noted that pressure gauges and stabilizers that use circular and helical mechanisms have less friction and higher sensitivity
.
Spiral tube barometer (Spiral Tube):
This sphygmomanometer consists of a tube that is wound around it in a spring-like spiral. This barometer has the ability to measure high pressure by rotating its 360 degrees and also has a higher sensitivity and accuracy of measurement than the design.