PRESSURE GAUGES

You can define a manometer as the instrument for measuring the pressure of a gas or a liquid such as water or oil. Despite the emergence of digital models, analog gauges they are still the most demanded. 

What is a pressure gauge for?

In the case of manometer used for irrigation systems, the one that interests us here, helps us to know the water pressure, thus avoiding possible damage to crops, caused by vibrations or shocks.

It is a curious instrument, which has its complexity as well as a long history. But how could we define this device well?

What really is a pressure gauge?

As we said before, on a large scale, a Pressure Gauge It is the instrument that measures the pressure of a fluid or a gas. Or what is the same, a manometer It is that instrument capable of measuring the pressure difference between two fluids (either liquid or gaseous). Or between two different points in the same fluid.

El manometer It is used to measure the interactions that exist between different fluids that are compressed or enclosed. In this way they can be handled safely and with little risk. 

As we mentioned at the beginning, a manometer It is not only made to measure the pressure of liquids. There are also pressure gauges that are designed to measure the pressure of different gases. Without going any further, it is the device that we find at gas stations that indicates the air pressure in our tires. 

Therefore, a more complete definition of manometer It would be an instrument used to measure the pressure of certain fluids (liquids or gases) that are compressed in different closed spaces or containers. 

And at this point, we will also explain what its different elements are, as well as its exact function and how the pressure gauge measures pressure. 

What are the main elements of a pressure gauge?

The main element that constitutes a Pressure Gauge common is what we know as a Bourdon tube. It is an elongated, spirally wound tube that has one open end and one closed end. 

The open end is connected to a nozzle, which will go directly to the fluid. The other end will be connected to the dial, which contains the needle that will indicate the fluid pressure.

Therefore we are talking about a manometer It is mainly composed of the Bourdon tube, the needle, the dial (usually rotating), a metal pointer and a connection. 

It should be remembered that this tube has two ends, one closed and the other directly connected to the fluid that exerts the pressure.

And knowing the main elements that make up a manometer we are going to explain the key to everything; its operation. 

How does a pressure gauge work?

Now that we know what a manometer we are interested in knowing how it works. As we said, this device measures the pressure of certain fluids (liquid or gaseous). Or rather the pressure difference. 

As these fluids are in a closed container, they will normally have an absolute pressure other than atmospheric pressure. This difference between the two pressures is what a Pressure Gauge. 

Atmospheric pressure is the value taken as a reference for this instrument. The manometer measures the actual or absolute pressure difference and atmospheric pressure. We call that value gauge pressure. In this way, the result of the pressure gauge may be above or below the reference value (atmospheric pressure).

Normally, pressure gauges Most commonly used are analog devices. They have a circular dial and a pointer that is actuated mechanically. But as we have already mentioned, there are also (how could it be otherwise) the digital pressure gauges. These gauges usually have a digital display and other additional features, such as the incorporation of alarms or the wireless retransmission of the indicated value.

Even so, as we have already pointed out above, the analog gauges they are still the most demanded. They have great reliability and a good price in relation to their benefits. 

Times change and it is normal for the pressure gauge to adapt as well. And we are talking about an invention with a long history behind it.

  The origins of the pressure gauge

The measurement of the pressure of a liquid or a gas in a container dates back to the time of Galileo Galilei. This great character carried out multiple experiments related to the pressure pumping. 

In 1594, Galileo Galilei obtained a patent for a machine to pump water from a river, for the purpose of irrigation of land. The center of the pump was a kind of syringe. He discovered, among other things, that 10 meters was the maximum height that the sucked water could reach, but he did not find any explanation for this phenomenon. 

Many scientists continued to experiment with these pressures for years, but it was not until 1644 that Evangelista Torricelli unveiled the first pressure gauge in history. Specifically, it did so by filling a one meter long tube hermetically sealed with mercury and placing it vertically. This tube had, as you can already guess, one open end and one closed end. 

This end ended in a container with mercury and he observed that, invariably, the mercury column dropped about 760 mm, leaving an empty space above this level. 

Torricelli attributed this phenomenon to some force on the surface of the earth, but he never knew exactly where it came from. 

During the following years, several chemists and physicists continued to investigate the experiments of Galileo and Torricelli, such as Pascal, Robert Boyle or Gay-Lussac (who established the relationship between pressure and temperature).  But it was not until the 1849th century that Eugène Bourdon, a Parisian watchmaker and engineer, invented and developed the Bourdon pressure gauge, Pressure Gauge which continues to be one of the most widely used today. 

Therefore, we could say that it was Eugène Bourdon, with the permission of Torricelli, the true inventor of the current Pressure Gauge. This instrument is based on a very simple principle, that of the Bourdon tube (remember the spiral tube with one end open and the other closed).

El Bourdon manometer It is one of the most widely used pressure gauges today. But over the years, different scientists and engineers have developed other more specific models. 

Types of pressure gauges

As we have already mentioned, we can find several types of pressure gauges today: 

Bourdon manometer or Bourdon tube

As we have just pointed out above, the manometer Bourdon's tube consists of nothing other than an airtight metal tube that is closed at one end. This tube is wound into a spiral. 

Two-leg open manometer (or U-shaped glass)

The simplest version of this manometer It consists of a glass tube bent into a U-shape that contains a liquid. One of the branches of the tube is open to the atmosphere while the other is connected to the container in which the fluid whose pressure is to be measured is located. 

Truncated pressure gauge

This manometer It is mainly used to measure small gaseous pressures. Its conception is simple. It is a siphon barometer with its two short branches. 

As in the previous case, one of the branches will be attached to the tank in which the substance whose pressure we want to measure is located. On the contrary, in the closed branch of the manometer a structure known as emptiness o barometric camera.

Metal or aneroid manometer

These types of manometers are barometers that have been modified in such a way that, inside their box, the pressure that we want to measure acts, while the atmospheric pressure acts outside. 

These are the most common types of pressure gauges What can we find. But there are other classifications depending on other factors.

For example, at Bourdon manometer We can classify it according to its diameter, its sensitive element or the manufacturing material. According to this last classification, the most common that we can find are those that contain glycerin. 

This compound, due to its viscosity, dampens the possible vibrations that the manometer, preventing condensation and prolonging its life. Without the glycerin, the needle would move depending on the vibrations, producing possible deviations of the measurement.

The glycerin gauges They are indicated for reading water pressure. They are designed to be installed in environments with corrosive agents, excessive vibrations, large amounts of dust or in places where line pressure has water hammer caused by sudden pressure changes.  

En Mundoriego we have a wonderful selection of various glycerin gauges available according to the pressure needs demanded by the installation of the irrigation system. We have selected this type of pressure gauge because it is the ones with the greatest reliability and durability.

If you have any questions related to our water pressure gauges or any other question, you can contact us on the phone +34 655 968 154. Or if you prefer, you can write us an email to info@mundoriego.es. 

Our customer service team will assist you as soon as possible.   For more information click here filters / pressure gauges / air valves