One of the devices that direction Pressure measurement Is used, Manometer Is, indeed Barometer manometer Is used to measure the gas pressure trapped in a container.
The most important factor in measuring the pressure of the Broadon pipe is the Broadon pipe, one of the main parts Manometer It is made with an almost oval cross section in the shape of C, one side of which is blocked and the other container is connected to the pressure point. Bourdon-type barometers can measure from 30 to 50,000 pounds per square inch. The applied pressure causes the free tip of the Bourdon tube to move, and this movement is transmitted to the gear and hand by the lever system, and the hand on the plate shows the pressure.
Other types of manometers include the U-shaped manometer, which is a U-shaped tube with one end open and the other end connected to a gas container.
Mercury or other liquids can be poured into this tube. The height of mercury in the two branches of the pipe is equal, but with the opening of the container valve and the entry of gas into it, the height of mercury in the pipe changes and the gas pressure is measured according to it.
Manometers Can be used indirectly to measure other variables such as fluid / gas flow, velocity, liquid level and altitude. The standard unit of pressure in the SI device is Pascal, which is equal to 1Pa = 1N / m2. One Pascal is equal to one Newton It is a force that enters a square meter of physical surface.
Bourdon-manometer manometers are used to measure a wide range of pressure differences (about 700 MPa). Due to the long length of the pipe Manometer And other practical considerations, for Measuring high pressures They are used in refrigeration. You can see the mechanism of this pressure gauge in the figure below.
Bourdon tube consists of an elliptical curved metal tube that tends to open as the fluid pressure increases and becomes more curved as the pressure decreases. Curvature changes are transmitted to the 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. Bourdon barometers are used to measure pressures above and below the atmosphere.
From Manometer The U-shape can be used to measure pressure, vacuum or pressure difference between two points. This method is one of the simplest and at the same time the most accurate methods of measuring pressure. This method is usually used in cases where the operator needs to view the pressure locally.
Types of barometers according to the type of pressure
Pressure sensors can be classified according to the measuring range, operating temperature range and most importantly the type of measuring pressure. According to the type of pressure, barometers are classified into 5 categories:
Absolute pressure sensor
This sensor measures the pressure of a point relative to a complete vacuum (0 psi). Atmospheric pressure is 101,325 KPa (or 14.7 psi) above sea level relative to vacuum.
Gauge pressure sensor
This sensor is used in different applications because it can be used for Pressure measurement Calibrate one point relative to atmospheric pressure at another point. Tire pressure gauge is an example of a gauge pressure gauge. When the tire pressure gauge reads 0 psi, the pressure inside the tire is 14.7 psi. That is equal to atmospheric pressure.
Vacuum pressure sensor
This sensor is used to measure pressure below atmospheric pressure at specific points. The vacuum sensor reference is different in the industry, which may cause errors; Pressure relative to atmospheric pressure (such as measuring negative gauge pressure) as well as pressure relative to vacuum pressure.
Differential pressure sensor
This sensor measures the difference between the pressure of 2 or more points, which are introduced as inputs. For example, measuring the pressure drop in an oil filter. Differential pressure is also used to measure flow or surface area in tanks.
Sealed pressure sensor This
sensor is the same as the sensor Pressure gauge With the difference that it is pre-calibrated by the manufacturer to measure the pressure relative to the sea level pressure.
Application of manometers
Pressure measurement
This application is the main application of pressure sensors in cases such as equipment Meteorology, Airplanes, cars and other devices in which pressure is applied.
Measuring altitude
It is used in airplanes, missiles, satellites, meteorological balloons, etc. In all these applications, the relationship between pressure changes and altitude relative to sea level is used.
Flow measurement
Flow can be measured with the help of the Venturi effect and its relationship to pressure. The pressure difference between the two parts of a net tube (with different orifice diameters) is measured. This pressure difference is directly related to the velocity of the flow through the tube. Because this pressure difference is relatively small, a low-interval pressure sensor is used.
Height / depth measurement
A pressure sensor can be used to measure the height of the liquid surface. This technique is commonly used to measure the location of a body immersed in water (such as divers, submarines) or the height of the liquid level inside a tank (such as liquid inside a water tower).
Leak test
System leakage can be measured by measuring the pressure drop. Common methods for this purpose are two methods:
1) Comparing system pressure with system pressure with known leakage and using this pressure difference.
2) Measuring pressure and examining its changes over a period of time.