Elastic barometer
The property of material deformation due to pressure is used in the construction of elastic barometers . Diaphragm, capsule, Bourdon and tail sphygmomanometers (Bellows) are the four main types of these sphygmomanometers. In these barometers, the quality of the alloy used in its construction is very important.
Elastic pressure gauges are widely used in the oil, gas, ship, aircraft and other industries.
Diaphragm pressure gauges :
The diaphragm is actually a flexible metal disc that is flat (corrugated) and flat. Diaphragm pressure measurement is one of the methods of measuring pressure in instruments. Diaphragm sphygmomanometers are mainly used to measure pressure differences. Diaphragm sphygmomanometers are basically mechanical pressure transducers.
In the pressure difference cell (Dp cell), the mechanical deformation of the diaphragm plate causes a small displacement and elongation of the diaphragm surface. These two features, namely displacement and surface elongation, can be used independently to measure the amount of pressure difference applied. In fact, the amount of tension and displacement created has a certain relationship with the pressure difference. In this way, by having one of the pressures, the unknown pressure can be obtained.
In general, the working principle of a diaphragm sphygmomanometer is such that first the flat or folded plate of the diaphragm, which is connected to the hand with a lever, deforms due to the pressure applied to the A plate. This deformation leads to a proportional movement of the lever, moving with the push of the lever of the pointer. The movement of the hand on the calibrated screen reports the applied pressure to the user. The diaphragm can be metallic or non-metallic. Provided that the selected metal must be Elastic. Leather and rubber are also common in diaphragm construction. Non-metallic barometers are large in size and are mainly used to measure lower pressures.
Capsule pressure gauge :
Because many non-metallic diaphragms are vulnerable to corrosion and impact, two diaphragms are commonly used. The first diaphragm in contact with the fluid is usually made of stainless steel. Deformation of the first diaphragm under fluid pressure will cause an interface fluid that is incompressible as well as corrosive to move. Silicone oils, which absorb shock and vibration, are commonly used as transmitting fluids. This fluid transmits pressure to the second diaphragm, which is generally non-metallic.
.Capsule barometers can consist of two or more connected diaphragms with higher measurement accuracy
:Lamp Barometer [ Bellows Tube ]
Lantern is a flexible piece made of metal or rubber. The length of the bolt (lantern) changes due to pressure applied to this piece. In general, the blouse has a structure similar to an accordion and a blacksmith’s tail. The structure of the tail accordion causes it to expand and change its size proportionally due to pressure. The relations of pressure, opening and closing of the tail are similar to spring relations. These relationships are as follows:
X = Ks (PA)
P Pressure being measured, A bulls clip surface, Ks Bulls elasticity coefficient
Bourdon Barometer (Bumblebee Tube):
The Bourdon tube consists of an oval curved metal tube that tends to open as the fluid pressure increases and increases as the pressure decreases. Curvature changes are transmitted to the barometer hand via a gear system. The direction and amount of hand movement depends on the direction and amount of change in the curvature of the pipe . The Bourdon barometer is used to measure more and less pressure from the atmosphere.