Pressure gauge


There are currently many types of measuring instruments which are used to make comparisons between different proportions or magnitudes following a standard measure or pattern. One of these instruments is known by the name of a manometer , a device created to be able to make measurements between different fluids or substances.


What is a pressure gauge?

The manometer is a measuring instrument that is used to know and have exact data on the pressure of fluids or gases that are located in closed containers or containers.

  • What is a pressure gauge for?
  • History
  • Pressure gauge features
  • Types
  • Parts of a pressure gauge
  • How does it work
  • How to use
  • How it differs from the barometer
  • Importance

What is a pressure gauge for?

Basically, the manometer is an instrument that is used to make pressure measurements , they are generally used to be able to make measurements of contained gas, so it can be said that they measure this pressure in relation to the existing atmospheric pressure .



The history of the manometer begins in ancient times , at a time when observations began to be made to determine whether air could be sucked in through the upper end of an open tube by means of a pump, one of the ends of the tube remaining inside a bowl of water.

The first man to notice the operating process of the instrument was Viviani in the year 1644 , one of Galileo’s disciples who made the claim that atmospheric pressure, the maximum height of the water inside a closed vertical tube and the vacuum could measure atmospheric pressure appropriately.

In 1644 , Torricelli managed to fill a tube that was hermetically closed with mercury , which he placed vertically, keeping one of its ends open. After doing his experiment, he concluded that the phenomenon was produced by the force that was on the surface.

In the 19th century , Eugéne Bourdon carried out several experiments using the bourdon tube , which was used to make measurements on the pressures of fluids and atmospheric pressure, thus creating the manometer.

Pressure gauge features

Some important features of the pressure gauge are as follows:

  • It is considered one of the simplest measuring instruments .
  • It is based on the Bourdon principle .
  • Measure gauge pressure .
  • Make comparisons between external and internal atmospheric pressure .
  • The type of measurement they do is relative .
  • They have two scales , one that marks the bars and the other that marks the psi.


Currently there are three different types of pressure gauges, which are explained below.

  • Simple manometers : they are also known by the name of analog and are formed by a glass tube which has its ends connected to a point, where the pressure is measured, and another end that is in contact with the atmosphere . In this group several types can be found:
  • Piezometer : This is a very simple way to measure pressure and has one end connected to the point where the pressure will be measured and the other end open.
  • U-tube manometer: in its U-shape they contain a fluid and to function it follows the principle of hydrostatic equilibrium.
  • Cistern or well pressure gauge : in this type of instrument, the well is larger than the area of ​​the tube.
  • Inclined type : they have a tube that is not in a vertical position, on the contrary, they have a shallow angle if it is related to the horizontal plane.
  • Absolute Gauge – They have a type of sealed leg that has a vacuum condition and represents absolute zero pressure.
  • Digital pressure gauges

They are known as electronic manometers and have a pressure transducer that has the ability to convert the pressure level which is observed into an electrical signal that has a value proportional to the magnitude of the pressure . This type of pressure gauge uses three different electrical parameters; one resistive , one capacitive and one inductive .

Parts of a pressure gauge

As for its parts, it is important to mention that the manometer has an elongated tube wound in a spiral shape , this part has an open and a closed end . The closed part of the tube is connected to a nozzle , which is in contact with the liquid while the opposite end is in charge of moving a needle that is in charge of indicating the pressure of the fluid.

The structure of every pressure gauge therefore has the following parts:

  • Pressure gauge needle indicating force.
  • Connection.
  • Pier, which is also known as Bourdon tube
  • Sphere, part where the components of the pressure gauge are located.
  • Rotary dial.
  • Union of pressure connection,
  • Metal pointer
  • Open and closed ends

How does it work

The operation of the pressure gauge will always depend on the type of instrument used and its operation is based on the principle of hydrostatic balance . In general , mercury is used, which has a U-shape. Its operation begins when a liquid that is usually mercury is placed at one of its ends and then the gas that needs to be measured is introduced. The tube is capped correctly to avoid leaks, leaving one of its ends open to measure the natural pressure .

When an adequate balance or balance is achieved, the liquid under study is pushed through the air that manages to enter through the open part of the tube. When this equilibrium is achieved, then it becomes possible to have the atmospheric pressure measurement .

How to use

There are several uses that this instrument can have, but the main one is to measure the pressure that is inside a container. It is also used to introduce air into automobile tires and, at the same time, to be able to measure internal tire pressure .

In the water pipes of the houses the pressure gauges can measure the pressure that the water has and in the boilers it is used for the same purpose but it is done as a safety measure . They are widely used within the industrial sector as they can provide very accurate pressure data. The laboratories also use the gauges and are ideal for measuring the drop in pressure filters , for testing leaks and to meet the fluid levels inside tanks.

How it differs from the barometer

The main difference between these two instruments is based on the fact that the manometer is in charge of measuring the different pressures that exist inside closed containers, while the barometer is the one whose purpose is to be able to measure the atmospheric pressure found in open containers.


The pressure gauge is a very important instrument because thanks to it it can be guaranteed that there are no leaks within a system or a machine, especially those that must keep the pressure under control . They are then necessary to be able to determine the presence of errors that can at some point significantly affect all the operating conditions that a thermal or hydraulic system has.

Currently, this instrument is a very important device because thanks to it it is possible to obtain exact and precise measurements on the pressures of different materials and substances . There are many applications that need it and that make it important, from the health field to the industrial area as in the case of the automotive industry , diving , studies carried out in outer space and in the elaboration of the refrigerators .

Leave a Comment