Pressure gauge

November 2, 2021

The pressure gauge or manometers are tools used to measure the pressure in fluids, usually determining the difference between the fluid pressure and the local pressure. Technically speaking, pressure is defined as the force exerted by a liquid or gas on a surface per unit (Newton per square meters generally), being perpendicularly on the same surface.

How does it work?

The way the pressure gauge works is as follows:

First, a liquid must be placed in the tube that is stable under pressure, generally mercury is recommended One end of the U-shaped tube is filled with the gas or liquid whose pressure is to be measured; it is usually pumped into the tube so that it can be sealed later and the other end is left open so that it can have a natural pressure level.

The pressure pushes the stable liquid towards the closed end through the tube and in turn the other liquid or gas pushes the stable liquid towards the open end. At that time the measurement is made taking into account how much the stable liquid has been pushed through the tube, either to or above the open end.

If the stable liquid is level on both sides of the tube, the pressure of the gas or liquid is considered to be the same as the pressure of the air in the atmosphere. If the stable liquid is higher on the side of the sealed end, then the pressure is lower than that of the air in the atmosphere. And when the stable liquid is pushed to the open end, then the pressure is higher than that of the air in the atmosphere.

Types of pressure gauge

Three classes of pressure gauges can be defined with different characteristics and functions that make each one a useful instrument to a great extent; The three types of pressure gauges are:

  • Meter with tubular spring. This indicates the measurements taken using a spring; the way it does it is with the bending of said spring when obtaining the pressure measurement. The spring flexes as much as the pressure, the higher it is, the more it flexes. When this system operates, the gauge indicates with a needle the amount of pressure measured.
  • Membrane pressure gauge. The degree of bending exerted on the membrane is equal to the value of the measured pressure, that is, the more the membrane bends, the greater the pressure. In this meter, the membrane is held between two flanges that prevent it from detaching when it is being used.
  • Pressure gauge with capsule. This specific type has a capsule which has membranes at its two ends that are indifferent to the pressure to which they can be exposed. The increase in pressure can be indicated at the moment when the capsule expands, thus indicating a certain value of the total pressure.

Pressure Gauge Features

Regarding its characteristics, there are several notable ones in terms of pressure meters; You can mainly start by pointing out what they use to make their measurements, the atmospheric pressure . Most pressure gauges use pressure as a base measure to be able to calculate the measure of other pressures, beyond that, some equipment also use vacuum as a reference measure, these are called vacuum gauges and are considered more neutral than the pressure gauges.

The way in which the measurements of the pressure gauges are expressed is with values ​​that are either greater or less than the atmospheric pressure used to calculate them.

Pressure gauges usually use mercury as a stable liquid and sometimes aneroid, both useful since neither is essentially affected by the force of atmospheric pressure when taking pressure measurements; at the time of doing so they calculate the real pressure, the absolute pressure and the atmospheric pressure.

Atmospheric pressure is used as a neutral point when making measurements and higher values ​​are positive while lower values ​​are negative. It should be noted that the end result is called gauge pressure .

As already explained, the pressure gauge calculates the pressure of liquids or gases with either of them being enclosed in the hermetic container that the pressure gauge has.

Pressure gauge functions

Its very name fully explains its function, but how pressure measurements can be applied is something that is not so clear. Its uses can range from something quite everyday to more technical, some examples of the use of pressure gauges can be:

  • When a tire is inflated, it can be used to determine the air pressure inside the tire.
  • Measuring the pressure inside a gas cylinder is very useful in cases where you have no idea of ​​the amount of gas remaining, although it must be a delicate process.
  • Pressure gauges are also used to measure the pressure in household water pipes .
  • In addition to this they are used in boilers for safety measurements and in industries they are widely used when the amount of pressure of a fluid production must be calculated.

Parts of a pressure gauge

The meter basically consists of 10 parts responsible for the efficient operation of the meter itself and these parts are:

  • Tubular spring, membrane or capsule. Where the measurement is performed.
  • Tight. This is responsible for pulling the mechanism in relation to pressure.
  • Mechanism. It transforms the force that the strap exerts to transmit it to the needle.
  • Needle. The needle points to the value of the measured pressure.
  • Sphere. There are all the components of the meter.
  • Union. Regulates the pressure connection.
  • Dial. This is usually rotary and there is the needle.
  • Metallic pointer.
  • Aneroid. It has a box that maintains the structure of the meter.
  • The two ends of the tube. There is one that must be hermetically sealed together with the one that must be open to perform the measurement

All these are the essential parts of a pressure gauge, thanks to them its operation can be optimal and efficient without generating inconveniences.

Pressure gauges are practical and widely used devices even in more than everyday activities, because of this, taking into account what has been presented about them is useful for those who want to know a little more about these tools.

Dr. Loony Davis5
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Born and raised in Brussels in an English family, I have always lived in a multicultural environment. After several work experiences in marketing and communication, I came to Smart Water Magazine, which I describe as the most exciting challenge of my career.
I am a person with great restlessness and curiosity to learn, discover what I do not know, as well as reinvent myself daily, someone who is curious about life and wants to know. I enjoy sharing knowledge.
This is my personal project but I also collaborate in other blogs, it is the case, the most important web on water currently exists in the US, if you are interested you can read my articles here.

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