Vacuum sensors: principle of operation

2024 Author: Erin Ralphs | [email protected]. Last modified: 2024-02-19 11:42

Sensor Vacuummeter - it is also a pressure display device. In this article we will consider their types, the principle of operation. There are such types: compression, mechanical, membrane.

It is also called "vacuum gauge" in another way. It is for people a device for measuring the pressure level of vacuum and gases, which, in turn, are in a vacuum environment. In general, one could understand by the name.

Leonardo Da Vinci laid the foundation for these devices. He made some kind of functional device with which he was able to measure the pressure in a water pipe. This invention became very popular and necessary for those years when Da Vinci lived (1400s).

His invention was improved by Evangelista Torricelli, who filed a patent for this device. This was done in 1643, more than a hundred years after the death of Da Vinci himself. The vacuum sensor was shaped like a U and the main element on which it worked was mercury. Unfortunately, due to its limited amount in the tube itself, it was impossible to determine a pressure higher than 9 pA. Everything changed the appearance of a digital vacuum sensor (its photo is presented below in the material).

Types of gauges

Mechanical gauge.

This is a device that does not use power sources, and it is able to determine the level in the range from 0.4 to 7000 bar. Its mechanism of operation lies in the fact that there is a certain ring, which is located in a pipe with an oval section, which in turn is bent at an angle of 240 degrees.

It is in the groove and its ends are not fixed, and this allows the pressure in the process of measuring it to press inside the tube, setting it in turn in motion. It is associated with a mechanism that displays accurate readings already on the scale of the device. Usually the device measures pressure up to 65 bar, but there are devices for higher readings, about 7100 bar.

To use the vacuum sensor in a more aggressive environment, its body is filled with a waterproofing agent, which lubricates the mechanism and thus prevents corrosion. As a protection of this mechanism, in order to protect the tube from rupture, the gauge body is equipped with a blown wall that relieves excess pressure.

Invention of the Bourdon tube

The tube is U-shaped and is called a hydrostatic gauge.

It shows the results of the pressure on the liquid that this tube has detected. The parameters at different ends of these two tubes are different, and the arrow of the device shows the difference between them. Today, such a device is no longer used, because the pressure range has changed and the device has become completely unnecessary.

Compression gauge.

Thismanometer, only very advanced. To expand its capabilities, it was designed in such a way that before the measurement it compresses the liquid in the tube, and the scale shows the pressure level. In everyday life, it is used simply as a calibration device.

Deformation gauge, mechanical

This pressure gauge is usually intended for low vacuum measurements. Under the pressure of the tube, the spring in it is compressed and deforms the workplace, and it, in turn, transfers the load to the pointer mechanism, called the indication scale.

Vacuum diaphragm pressure sensor.

This is the most affordable version of the movement. Principle of operation: vacuum presses on the membrane, and it presses on the sensor. Such devices are always independent of the medium and take readings in any gas mixture.

Thermal mechanisms

Thermal vacuum measurement sensors are considered the most in demand, they take readings in both medium and low vacuum frequencies. It is in these devices that such indicators that are important for people as quality and low price are combined. They can only be used for measurements in absolute vacuum. The principle of operation is as follows: the reaction of the vacuum gauge to a change in the gas heat pipe with a change in pressure.

Instruments vary depending on the type of gas itself and read only certain mixtures. The most common modification is a thermocouple vacuum sensor, and there are also Pirani devices and convection mechanisms.

Thermocouple device.

Suchthe temperature sensor in vacuum affects the heating of the thermocouple inside the mechanism, which provokes a change in voltage at the ends of the thermocouples. The transfer of heat from heating the sensor itself to its ends is due to the pressure around the thermocouple. The higher it is, the greater its voltage. Such vacuum gauges are very budgetary among a group of other similar ones.

Pirani Sensor

This mechanism and principle of operation is similar to thermocouple. It uses a channel filament and converts thermal energy into voltage. The Pirani mechanism is much more accurate than others, due to the electrical circuit soldered into the mechanism.

Convection sensor.

He also, like similar devices, uses a thermocouple. But the mechanism of this particular device has its own cooling. After all, the case is wrapped around with a special thread, and it is wider than that of analogues. And it, in turn, allows the gas in the sensor to circulate correctly and efficiently, and this allows the entire convection device to work better as a whole. It also gives much faster readings on the scale due to the rapid cooling of the thermocouple.

Piezoresistive mechanisms

The photo above in the material shows an electronic vacuum sensor.

Because of their independence from gas quality and properties, they provide the most accurate readings. The device has versatility in any range of pressure frequencies, because the influence of the latter is achieved by the direct action of a piezoresistive sensor. Its measurement range is from 0.1 mm. Toyota vacuum sensor, for example,works the same way.

Ionization based vacuum sensors

The working principle of the vacuum sensor of this model is described below.

Any gas in a vacuum has, in fact, a certain number of ions. A magnetic field or electric discharge acting on them accelerates them. And this speed, typed by them, depends on the degree of compression of the vacuum. According to this principle, such ionization gauges work.

Depending on the modification, gauges use a variety of and sophisticated ways to accelerate ions. These devices are usually designed for measurements in a high vacuum range. Since they are gas dependent, and each gas has a different density, this affects the speed of the ions.

A device that always has a cold cathode

This is a sensor that creates an electric field. Its magnets are positioned so that the movement of ions occurs along the trajectory of a spiral. It is she who gives these particles to "live" longer, and, therefore, to work more efficiently. Due to the fact that this very cathode is always cold, its readings on the scale are more vague, unlike the analogues of this device. But at the same time, the guarantee of this very device is very long, and it does not often break down due to its durable parts that cannot create friction against each other.

Producers

The first manufacturer of vacuum gauges presented in this article is "Meta-Chrome". This is a domestic company that produces not only these devices, but also chromatography equipment and measuring equipment. This Russian company entered the market in1994, and since that time it has been developing and producing equipment for the vacuum industry. Its products are supplied not only in Russia, but also abroad. The Meta-Chrom enterprise always produces a high quality product, ionization and thermocouple vacuum gauges without marriage and work without breakdowns. This is confirmed in 90% of cases by positive feedback from customers and buyers of this manufacturer's products.

The second company producing vacuum gauges is MKS Incorporated, an enterprise from the United States of America. They founded their company selling sensors and other measuring devices much earlier than their Russian counterparts, as far back as 1962. But then they did it very superficially. And completely, as a manufacturer of such equipment, it began to position itself only since 1998. MKS makes vacuum gauges for their country, but like our domestic company, they can ship their products to other countries for a small shipping fee.

The third manufacturer featured in the article is Ulvac Technologies. It is also an American manufacturer for the production of various measuring instruments, such as a vacuum gauge. This company was founded in 1991. Their market has always had a lot of digital vacuum gauges and other products that they supply both in their country (United States of America) and in other countries of the world.

Conclusion

The vacuum gauge is a very complex thing that you need to learn how to handle and correctly determine the pressure. This article has shown alltypes of these sensors, there are only about 10 of them. This is a very important item in the trunk of motorists and car repairmen.