THE 10 MOST RELEVANT PRESSURE MEASURING INSTRUMENTS - SCIENCE - 2025

The instruments for measuring the pressure are devices different materials is an element which changes somewhat when subjected to pressure. That change is recorded on a calibrated scale or display, and is expressed in units of pressure.

The units of measure in which pressure is expressed indicate a unit of force over a unit of area.

Although the standard unit of measurement is Pascal (N / m2), it is also measured in pounds per square inch (PSI), in atmospheres (atm), in kilograms per square centimeters (kg / cm2), inches of mercury (Hg) and millimeters of mercury (mm Hg).

In other words, pressure is force per unit area. It is experienced when that force is perpendicular to the surface.

Pressure types

The different types of pressure are:

• Of emptiness.
• Absolute.
• Dynamic.
• Static
• Atmospheric.
• Manometric.
• Differential.
• Barometric.
• Stagnation.

There are several instruments to measure pressure, and although most are used to measure relative pressure, there are some designed to measure absolute pressure.

Top 10 instruments for measuring pressure

1- Differential pressure gauge

It is also known as the two-branch open manometer. This is a device used to measure the pressure difference between two places.

The fluid that the differential manometer uses to indicate the values ​​can be any liquid: water, kerosene, alcohol, among others. The essential condition is that it does not mix with the fluid that is under pressure.

In case you are trying to measure high pressures or very large pressure differences, the liquid should be very dense. In these cases, mercury is often used.

In a manometer the measurements can go from 0 to 0.5 KPa (≈ 0.2 ”H2O); or from 0 to 7000 KPa (≈ 1000 psi).

2- Truncated pressure gauge

It is a type of manometer that is used to measure small gaseous pressures. It measures absolute pressures and has branches shorter than the differential.

3- Vacuum gauge

It is a device that is used to measure the vacuum; that is, to measure pressures below atmospheric pressure.

It turns out to be a very useful tool in cold plants or where liquefied gases are worked, since the critical points of gases and steam are calculated based on absolute temperatures and pressures.

Although the measurement range depends on the material from which it is made, it can cover measurements between -0.5 and 0 KPa; and -100 to 0 KPa (≈ -30 to 0 "Hg).

Some of the types of vacuum gauges are:

McLeod Vacuum Gauge

It is a direct reading quadratic scale analog vacuum gauge.

Piston-cylinder

It is a primitive method of measuring pressure known as a pressure or deadweight balance.

It consists of balances that have a vacuum chamber that is placed at the top to eliminate the correction of the air pressure.

4- Pressure sensors

Pressure sensors are devices designed to subject materials to a pressure that deforms them in their elastic range. Such deformation is proportional to the pressure used and is considered linear.

In this way, pressure sensors transform pressure into displacement. The sensor then converts the motion into an electrical signal such as voltage or current.

The most universal pressure transducers are:

• The strain gauge.
• The variable trainers.
• Piezoelectric.

5- U tube

It consists of a glass tube bent into a U-shape, which is partially filled with a liquid of known density.

One end of the tube is connected to the object or space in which the pressure is to be measured, while the other end is left free.

The pressure exerted at the high pressure end will cause the liquid to move inside the tube.

This movement will be reflected in a difference in level (or height) marked as h, which depends on the pressure and the density of the liquid in the tube.

6- Bourdon tube

It is a device with an elastic metal tube, which is flattened and curved in a special way. When pressure is applied, the tube straightens and its free end shifts.

It is this movement that moves the levers and gears, which end up moving a needle that indicates the pressure on the scale.

7- Bellows

This instrument has an elastic component in the form of a bellows or accordion, to which the pressure to be measured is applied.

When pressure is applied, the bellows is stretched and it is this movement that displaces the measurement indicator needle.

8- Diaphragm pressure gauge

This instrument is a variant of the bellows manometer. It is shaped like a disc with concentric circular corrugations.

In this device the pressure is exerted on an elastic diaphragm, the deformation of which is translated into the movement of the pointer indicating the measurement.

The diaphragm can also be metallic, in which case it uses the elastic characteristic of the material to be measured.

This type of pressure gauge is used to measure low differential pressures or vacuum pressures.

9- Barometer

It is the instrument used to measure atmospheric pressure. There are several types of barometers:

Torricelli tube

It is named in honor of its inventor Evangelista Torriceli, who devised it in 1643.

It consists of an 850 mm long tube that closes at the top and remains open at the bottom to fill it with mercury. The level of this liquid metal is what indicates the pressure there is.

Fontini Barometer

It is the improved version of the Torricelli tube and is used in meteorological stations to obtain very precise measurements and at different scales.

Metal barometers

It is a type of barometer that works on gas, so it is less sensitive than mercury ones, but it is practical.

Altimeter

It is the type of metallic barometer used to measure altitude above sea level.

Aneroid barometer

It is a cylinder with elastic walls that measures the variations in atmospheric pressure.

10- Sphygmomanometer

It consists of an inflatable cuff, a pressure gauge, and a stethoscope that indirectly measure blood pressure by auscultating Korotkov sounds.

It can work with mercury or air and requires the use of a stethoscope or stethoscope.

There is a variant of this device that is electronic. It is accurate and very easy to use, which is why it has become very popular. It is a very sensitive device to noise and movements.

References

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