Technical pressure gauge: in detail by a simple language. Instruments for pressure measurement

Technical manometer - a simple and accurate instrument for measuring pressure. It can be used to measure vacuum, pressure above atmospheric, pressure difference. The design of the pressure gauge determines how each type of pressure is measured.

Perhaps, in everyday life of the most famous manometers: a pressure gauge for measurement arterial pressure and pressure gauge for measuring automotive tire pressure.

Principle of operation of a technical pressure gauge

The principle of operation of the pressure gauge is based on the fact that the pole of a certain height fluid has a certain pressure. Changing the magnitude of the liquid columns when applied to the pressure source device is used as an indicator of pressure change.

As a liquid in manometers for the most part Used mercury and water. However, it is possible to use other, specially prepared liquids, for example, special oil. In colorless liquids, dye is usually added for convenience. The effect of the weight of the dye is negligible and the calculation is not accepted.

How to use a technical manometer

The main operations on the use of the pressure gauge include checking its condition, zeroing, application of pressure and removal of readings. If the liquid in the pressure gauge is contaminated, it should be replaced, otherwise it will reduce the accuracy of the measurements.

It should also be checked for a sufficient amount of pressure fluid in a pressure gauge. If the liquids are not enough, it should be done by topping in accordance with the instructions of the manufacturer of the device.

All pressure gauges must be leveled in terms of measurements. Without this measurement will be inaccurate. In most inclined gauges there is a special device for leveling the device. The device rotates until the bubble in the level index will take the correct position.

In order to ensure accuracy, a reference zero must be installed on the pressure gauge before the pressure is applied and the readings are removed. The reference zero of the pressure gauge is made in the form of a handle that makes it possible to set the zero mark on the scale according to the liquid level.

These preparations will help ensure the normal functioning of the pressure gauge. Then the pressure is applied and the necessary readings are removed.

How to read a pressure gauge reading

After the preparatory operations are performed, you can move directly to read the testimony of the pressure gauge. Figure below shows the levels of water columns for two types of tubes. The open surface of the liquid pillar is called a meniscus. The surface of the surface of the liquid shown in the figure is called a concave menist: the center of this surface is located below its external edges. Water always forms concave meniscus.

In practice, reading levels of levels for concave meniscovs is always made from the bottom, i.e. lower part of the meniscus.

There is also a convex meniscus. Its center is higher than the external edges. Mercury always forms convex meniscus. Reading readings with a convex of meniscus is always made from the top point.

Pressure gauges are accepted by the following signs:

- by type of measured pressure;

- the principle of action;

- accuracy class;

- appointment.

According to the measured pressure, the pressure gauges are divided into two groups. IN first groupinclude:

a) pressure gauges for measuring overpressure, with an upper measurement limit from 0.6 to 10,000 kgf / cm2;

b) Vacuummeters for measuring the range:

- Vacuummeters for measuring the resolutions (up to - 1.0 kgf / cm2);

- Manovakurammers, which are pressure gauges of both excessive (from 0.6 to 24 kgf / cm2) and vacuum (up to - 1.0 kgf / cm2) pressure;

- pressure pods - pressure gauges of excessive pressures up to 0.4 kgf / cm2;

- Practices - Vacuummeters with an upper measurement limit not exceeding 0.4 kgf / cm2;

- TyagonorPometers - Manovakuummers with extreme limits up to 0.2 kgf / cm2.

Secondthe group of pressure gauges is the gauges of absolute pressure, admired to measure the pressure counted from the absolute zero. These include:

- shortened liquid pressure gauges (measure absolute pressure);

- barometers - absolute pressure pressure gauges adapted to measure the pressure of the atmosphere;

- shortened barometers - mercury vacuum vehicles for measuring absolute pressure less than 0.2 kgf / cm2;

- Vacuummeters of residual pressure for measuring deep vacuum less than 0.002 kgf / cm2.

The mansion is worth thirdmanometer group:

- diffmanematers for measuring the difference of two pressures, of which none is pressure ambient;

- micromanometers for measuring pressures or pressure differences gas media With the upper measurement limit of less than 0.04 kgf / cm2.

On the principle of operation, the pressure gauges are divided into four main groups:

- liquid, hydrostatic principle based, when the measured pressure is equalized by the pressure pressure of the pressure gauge liquid;

- freight, in which the measured pressure or pressure difference is equalized by the pressure generated by the weight of the non-relaxed piston and cargo;

- deformation (spring) pressure gauges, in which the measured pressure or pressure difference is determined by deformation of the elastic element;

- Manometers based on other physical principles.

Under the accuracy class of the device, the limit value of permissible basic and additional errors, expressed as a percentage of the measurement range of a given instrument. Installed next ranges Manometer classes: 0.005; 0.02; 0.05; 0.15; 0.25;

0,4; 0,6; 1,0; 1,5; 2,5; 4,0; 6,0.

In the sign of metrological purpose, the pressure gauge can be divided into three groups: technical (workers); laboratory (control); Exemplary serve to verify other pressure gauges.

In liquid pressure gauges or diffmanematers (Fig. 2.4), the measured pressure or pressure difference is equalized by the pressure of the liquid column. The measure of the measured pressure in these devices is the height of the pillary fluid column, as which are more often used: ethyl alcohol, distilled water and mercury. Thus, the measurement of pressure is practically reduced to the measurement of a linear value, which can be performed easily with a fairly high degree of accuracy.

Consider the main types of liquid pressure gauges.

Two-pipe (U-shaped) pressure gauge. This pressure gauge (Fig. 2.4, a) is a U-shaped tube, or two tubes that are communicated by the lower parts. Pressure r1 I. r2 are found to both open ends. The difference of these pressure is converted into the difference in the level of liquid in the tubes. The conversion function has the form

D.h.=

D.p.

g.´ (ρ - ρc. )

where Δ. r- the difference in the outlook, PA; Δ. h.- difference in fluid levels in tubes, m; g.

R2

R2

d.T.

2

R1

d.P.

Crane (single pipe) pressure gauge. In the absence of two-pipe chains, the pressure gauges have a tank 1, communicated with the measuring tube (Fig. 2.4, b). Because of the significant difference of sections

Reservoirs and tubes have 1

place minor fluid change

in the tank. Countdown once?

levels at measurement - 5 4

Pressure Research is performed only on the tube. Before

Measurements set

R1 R2

Zero countdown when 0 α 0

pressures: r1 \u003d R.2.

Actual height 3.

fluid column

Δ h.= h.T - h.R ,

R2

R1

P 2.

here d.T.

- Diameters

tubes and tank. G.

Substituting (2.33) in

formula (2.32), we get

Fig. 2.4. Liquid manometers

P 2.

where l.- Length length of fluid in the tube.

The height of the hydrostatic pillar in the tube:

h.T \u003d. l.'Sinα, where α is the angle of inclination of the measuring tube.

After substitution h.P.

in (1.17) get

Δ h.= l.'(Sin α +

d.

T).

The magnitude in the bracket is called a constant pressure gauge. On the basis of such a pressure gauge, a micromanometer is arranged, in which alcohol is most often used as a working fluid.

Crack pressure gauge absolute pressure.The upper end of the measuring tube of a cup of absolute pressure of an absolute pressure (Fig. 2.4, d) is smeared. With the appropriate determination of the working fluid (usually mercury) in the cavity of the tube over the liquid, a pressure close to absolute zero. (p.2 = 0 ). In this regard, the height of the pillar in the measuring tube is proportional to the absolute pressure p.1. The height of the lifting of the liquid column is calculated by formula (2.32).

Float manometer. Unlike other types of cup manometers in floating (Fig. 2.4, e), the measuring element is not a tube 2, a tank 1 .

The tube performs the function of the balancing element. The output value is the flow of the float 3 located in the tank. The conversion function may be found from the equation:

D.p..

d.

)

g.'(Ρ - ρc)' (1 + T.

In this article we will try in detail all questions related to pressure gauges, their choice and their operation. Also, together with manometers, we will consider vacuummers and manovakummeters. All recommendations for these devices are the same, so we will mention only the manometers in the text.

1. What is a pressure gauge, a vacuum meter and a manovakummeter?
2. What are the pressure gauges?
3. What parameters are important when choosing a pressure gauge?
4. Translation of pressure manometer pressure units.
5. How to install pressure gauges?
6. How to exploit pressure gauges?
7. How is the verification of pressure gauges?
8. What pressure gauge is better to buy?
9. What is important to pay attention when buying a pressure gauge?

1. What is a pressure gauge, a vacuum meter and a manovakummeter?

Technical pressure gauge.

A pressure gauge is a device designed to measure the excess pressure of the working medium by deformation of the tubular spring (Bourdon tube).

Technical vacuum.

A vacuum meter is a device designed to measure the discharge of the working medium by deformation of the tubular spring. Standard scale for a vacuum meter from -1..0 atm. The scale on the vacuummeter is always negative, since the pressure is measured below atmospheric.

Manovacummeter technical.

Manovacummeter is a device designed to measure overpressure and discharge of the working medium by deformation of a tubular spring.

The foregoing simple:
- If only positive pressure on the scale of the device, then this is a pressure gauge.
- If only negative pressure on the scale of the device, then this is a vacuum meter.
- If there is a negative and positive pressure on the scale of the device, then this is a manovakummeter.

In industry and housing housing and utilities are the most common pressure gauges with tubular spring bourdon. This is due to the simplicity of construction and relatively low cost.

Manometer "From the inside".

2. What are the pressure gauges?

Technical pressure gauges - the most common instruments for measuring water pressure, air, gases that found wide application in the field of housing and communal services and industry. If you do not have any specific requirements for the device, it should definitely consider technical pressure gauges.

Technical pressure gauge TM610R.

Boiler gauges are technical pressure gauges with a 250mm body diameter. These pressure gauges are used when installing at high altitude or in hard-to-reach places, which allows you to read the instrument readings from a long distance.

Boiler pressure gauge TM810R.

Vibration-resistant pressure gauges - instruments for measuring pressure in conditions of increased vibration on the pipeline or installation. These devices massively apply on pumping stations, compressors, cars, ships and trains.

Vibration resistant pressure gauge TM-320P.

Corrosion-resistant manometers - devices made completely from of stainless steel and designed to work with aggressive media.

Corrosion resistant pressure gauge TM621R.

Welding pressure gauges - appliances intended to control pressure on oxygen and acetylene gearboxes, propane cylinders welding pressure gauges are oxygen (Blue body color), acetylene (body color white or gray) and propane (color red color). On the dial of each device in the circle is worth the type of medium.

Pressure gauges of accurate measurements (exemplary gauges) - devices with a low class of accuracy 0.6 or 0.4 are used for crimping gas pipelines, verification of technical pressure gauges, as well as for measuring pressure technological linesrequiring increased measurement accuracy.

Exemplary pressure gauge.

Maneometers ammonium-devices for measuring pressure in cooling systems. These devices are manufactured on the basis of corrosion-resistant pressure gauges with a changed dial.

Ammonia manovacummeter.

Automotive manometers - devices for measuring air pressure in tires. These devices can be bought in automotive stores or service centers.

Digital electronic gauges are two varieties: in a monoblock case and a set from a pressure converter and an electronic unit for indicating and regulating parameters. These devices are used to accurately measure pressure and in the automation systems of technological processes.

Electrocontact pressure gauges are technical manometers with an electrocontact consoles intended for switching contacts in automation systems.

The fundamental difference of these devices from the whole manometer variety is the presence of a parameter to execute a pressure gauge. To date, these devices are produced in six versions.

3. What parameters are important when choosing a pressure gauge?

In this section, we will look at all the parameters that need to be considered when buying a pressure gauge. This is very helpful information For buyers who have no accurate brand of the device or there is a brand, but these devices are not able to buy and you need to choose the analogues correctly.

Measurement range is the most important parameter.
Standard pressure row for pressure gauges:
0-1, 0-1.6, 0-2.5, 0-4, 0-6, 0-10, 0-16, 0-25, 0-40, 0-60, 0-100, 0-160, 0- 250, 0-400, 0-600, 0-1000 kgf / cm2 \u003d bar \u003d atm \u003d 0.1 mp \u003d 100kpa

Standard Pressure Pressure Mandations:
-1 .. + 0.6, -1 .. + 1.5, -1 .. + 3, -1 .. + 5, -1 .. + 9, -1 .. + 15, -1 .. + 24 kgf / cm2 \u003d bar \u003d atm \u003d 0.1 mp \u003d 100kpa

Standard row of pressure of vacuummers:
-1..0 kgf / cm2 \u003d bar \u003d atm \u003d 0.1 mp \u003d 100kpa.

If you do not know which scales to buy, the choice of range is quite simple, the main thing is that the working pressure falls into the range from 1/3 to 2/3 of the measurement scale. For example, you usually have a water pressure 5.5 atm. For stable operation, you need to choose a device with a scale of 0-10 atm, because the pressure 5.5ATM falls in the range from 1/3 to 2/3 of the scale 3.3 atm and 6.6 atm, respectively. Many are wondering - what happens if the operating pressure is less than 1/3 of the scale or more 2/3 of the measurement scales? If the measured pressure is less than 1/3 of the scale, the pressure measurement error will increase dramatically. If the measured pressure is more than 2/3 of the scale, the mechanism of the device will work in the overload mode and may fail before the warranty period.

The accuracy class is the permissible percentage of measurement error from the measurement scale.
Standard series of accuracy classes for pressure gauges: 4, 2.5, 1.5, 1, 0.6, 0.4, 0.25, 0.15.
How to calculate the error of the pressure gauge? Suppose you have a 10-atm per capita pressure gauge 1.5.
This means that the permissible error of the pressure gauge is 1.5% of the measurement scale, i.e. 0.15 atm. If the error of the device is more - then the device must be changed. Understand without special equipment, a serviceable device or not our experience is unrealistic.
Decide on the discrepancy of the accuracy class can only an organization that has a calibration unit with a reference pressure gauge with a precision class four times less than the accuracy class of a problem gauge. Two instruments are installed on a line with pressure and compare two testimony.

The diameter of the pressure gauge is an important parameter for pressure gauges in a round case. Standard row of diameters for pressure gauges: 40, 50, 63, 80, 100, 150, 160, 250 mm.

The location of the fitting - there are two types: a radial socket from the manometer from the bottom and the end (rear, axial) in which the connecting fitting is rear from the back of the device.

The connecting thread is the greatest distribution on manometers found two threads: metric and tubular. Standard row of threads for pressure gauges: M10x1, M12x1.5, M20x1.5, G1 / 8, G1 / 4, G1 / 2. Almost all imported manometers applied pipe thread. Metric carving is mainly used on domestic instruments.

The intermediate interval is the time when it is necessary to make an intertarization of the device. All new devices come with primary factory calibration, which is confirmed by the presence of the stamp of the belief on the dial of the device and the corresponding marker in the passport. On the this moment Primary verification is for 1 year or for 2 years. If the pressure gauge is used for personal purposes and verification is not critical, then choose any device. If a pressure gauge is installed on a departmental facility (thermal item, boiler room, plant, etc.), then after the expiration of the primary verification, it is necessary to control the pressure gauge in the CSM (center of standardization and metrology) of its city or in any organization that has a verification license and necessary equipment. For those who are constantly facing calibration of pressure gauges, it is not a secret that very often the hook is more expensive or comparable with the cost of a new device, as well as the delivery of the device in the calibration costs money even if the device will not pass the re-calibration and the instrument can be added to the price with subsequent calibration. .
Based on this, we have two reconnects:
- Buy instruments with primary calibration for 2 years, because Savings of 50-100 rubles on the purchase of an instrument with a period of calibration 1 year can already lead to expenses in 200-300 rubles and unnecessary "running".
- Before making the decision on the instrument protempted, clarify the costs of the nepper - in most cases much more profitable to buy new devices. What you need to calculate - the cost of calibration, several trips to the belief. If there are hydraulic blows in the system, the ripple of the medium ( close location Pumps), the vibration of the pipeline, then after 2 years of operation, usually 50% of the instruments are not passing, and it is necessary to pay for it, since the calibration was carried out.

Operating conditions- If the device will work on a viscous or aggressive environment, as well as when using the device in difficult conditions - vibration, ripple, large (more + 100 ° C) and low temperatures (less -40С), then you need to choose a specialized pressure gauge.

4. Translation of pressure manometer pressure units.

When buying a pressure gauge often, the need to measure pressure in non-standard units of measurement occurs. Our work experience says that if we are a small number of devices (less than 100 pcs), then the plants will not redo anything on their scales and will have to translate the units of measurements on their own.

1kgs / cm2 \u003d 10.000kgs / m2 \u003d 1bar \u003d 1atm \u003d 0.1 mp \u003d 100kpa \u003d 100.000pa \u003d 10.000mm. Body. St. \u003d 750mm. RT. Art. \u003d 1000Mbar

5. How to install pressure gauges?

For the installation of the pressure gauge on the pipe, three-way cranes and needle valves are used. To protect the pressure gauges, damper blocks are used, loop selected devices and membrane separators.

The three-way valve under pressure gauge is a three-way ball or cork valve intended for connecting a pressure gauge to a pipeline or any other equipment. Installing a two-way crane with the possibility of manual pressure reset from the pressure gauge when disconnected is allowed. The use of standard ball valves is not recommended, since after closing the crane, the mechanism of the pressure gauge is under residual pressure of the medium, which can lead to premature output from standing. To date, this is the most common view to attach pressure gauges at pressures up to 25 kgf / cm2. At high pressures, it is recommended to install needle valves. When buying a three-way crane, make sure that the carving on the pressure gauge coincides with the carving on the tap.

The needle valve is the capability of the gap capability of the smooth supply of the working medium in which the shut-off element is made in the form of a cone. Needle valves have been widely used for connecting various instruments of kipi to high pressures. When buying needle valves, make sure that the carving on the pressure gauge coincides with the thread on the valve.

The damper unit is a protective device that is installed before the pressure gauge and intended for damping the working medium. Under the pulsation B. this case It is implied by a sharp and frequent change in the pressure of the work environment. The main "organizers" of ripples in the pipeline are powerful pumps without devices. smooth start And the widespread installation of ball valves and disk shutters, the rapid opening of which leads to hydraulic shocks.

Dampfer block.

Looped selected devices (perkins tube) are steel tubes that are designed to clean the temperature before pressure gauges. The decrease in the temperature of the medium coming into the pressure gauge occurs due to the "stagnation" of the medium in the loop. These devices are recommended to be installed at a working environment of more than 80c. There are two types of selected devices: straight and angular. Direct selected devices are installed on horizontal areas of pipelines, and angular are designed to install on vertical pipelines. Before buying, you must make sure that the carving on the tube coincides with the thread on a three-way crane or pressure gauge.

Selective devices (Direct and corner).

Membrane media separators are a protective device for a pressure gauge, designed to protect the mechanism of the device from entering into it aggressive, crystallizing and abrasive environments. When choosing a membrane separator, it is necessary to pay attention to the coincidence of the thread on the pressure gauge and the separator.

Divider membrane PM.

When installing pressure gauges there are several requirements required to perform:
- mounting work with a manometer must be carried out with the lack of pressure in the pipeline
- pressure gauge is installed with vertical location Dial
- rotation of the pressure gauge is made for the fitting using a wrench
- Apply the force to the enclosure of the pressure gauge is prohibited

6. How to exploit pressure gauges?

When operating manometers, it is necessary to comply with the recommendations and physical parameters (medium temperature and permissible pressure) prescribed in the instrument passport. Most. an important requirement Operating is the smooth supply of pressure on the pressure gauge. If the device is properly correct and operated without disorders, then there are no problems.
Consider cases in which the operation of the pressure gauge is not allowed:
- When applying pressure on the device, the arrow does not move
- dashboard damaged or broken
- the device arrow moves jumps
- After resetting the pressure from the device, the arrow does not return to the zero mark
- measurement error exceeds permissible value

7. How is the verification of pressure gauges?

Pressure gauge is a means of measuring pressure and subject to mandatory verification. Verification of pressure gauges can be divided into two types:
- Primary verification is a calibration that is produced by the manufacturer before selling the device and confirmed by the presence of stimples on the glass or the package of the pressure gauge, as well as the corresponding mark in the instrument passport. Primary verification without any problems is recognized by controlling organizations and the instrument can be operated until the end of this period.

Pressure manometer - this is the calibration of the device that is made after the expiration of the primary verification of the pressure gauge. Before the manometer hopper, you need to make sure that the device is correct. To. In the event of a malfunction of the device, you for money comparable to the cost of the device, get a beautiful notification that the device is not working and need to be repaired or disposed. Pressure manometer is produced in the CSM (Center for Standardization and Metrology) of its city or in any organization that has a verification license and the necessary equipment.

8. What pressure gauge is better to buy?

To date, about 10 are represented on the market. russian manufacturers Devices, 2. belorussian manufacturer and a reasonable number of foreign appliances manufacturers. Consider the features of every devices.

Russian plants are the most optimal choice to purchase pressure gauges. Many will ask - why? Everything is quite simple - Russian manometers are significantly cheaper than imported with comparable capacity, the period of primary calibration for 2 years, unlike Belarusian, is produced by the entire line of instruments from technical to corrosion-resistant.

Belarusian plants are fairly cheap devices, but they have 3 significant drawbacks:
- Primary calibration for 1 year, which turns them to cheaper in the "myth" and "running" with recheck.
- Simplified mechanism, which, with serious loads, does not work for a long time.
- Plastic glass instead of the instrument also contributes to the operation and reliability of the device.

Foreign pressure gauges - our many years of experience in trade in devices shows that the meaning in the purchase is similar to the acquisition of the Russian instrument, but only 2-3 times more expensive. All explanations of the sellers of foreign devices on unique quality, super technologies, etc. are the usual trick to explain to the client, why he is so cool overpays. If the operating conditions are complex, you just need to buy a specialized device instead of technical and it will work without any problems. If you are tormented by doubts and you have the opportunity with a screwdriver to disassemble two similar pressure gauges Russian and imported - then you are unlikely lucky to find a few differences.

The exception is highly specialized devices with non-standard scales and parameters that are not produced in Russia.

9. What is important to pay attention when buying a pressure gauge?

- The pressure gauge must be new. Many device sellers under the word new understand that the pressure gauge was not in operation. But the pressure gauge can be 15 years old, and you will tell you that he is new. Specify the year of release of the device or you can wait for an unpleasant surprise in the form of a purchase of illiquid.
- On the pressure gauge or in the passport there must be a marker about the primary verification. There are non-liquid sellers who rub the story of the believer so that they can not be accused of selling old appliances.
- Verification on the pressure gauge should be 2 years, if you buy a primary calibration device for 1 year - after a year, savings will disappear and not necessary difficulties will begin.
- The manometer should be a passport and a valid certificate for measuring instruments.
- If the device is new and calibration for 2 years choose the cheapest option.
- Note the measurement range, the diameter of the scale, the type of fitting location, the type of thread and the execution of the device - if you buy not the device, then it can be conjugate with the difficulties, since if the device has non-standard parameters and is made under you, That most likely it will be necessary to keep a memory.
- Reviews about manometers on the Internet can be searched, but most of them are customized and better rely on the advice of people who have experience in real exploitation of devices.
- Pressure gauges worth buying in an organization that causes you trust, since the sale of non-liquids of the USSR still exists and then old instruments will be quite difficult to return or exchange to normal devices.

In this article we tried to consider the most popular questions About all the variety of manometers. If you want to consider other questions or with some other answers you do not agree - write to us and we will try to expand the article on the basis of your experience. In the letter, do not forget to specify your data, place, conditions and installation area.

Dear readers!

If you have a little comments on this article - please write on indicating the topic of this article.
If you like this article, please subscribe to our channel.

Have you ever used a manometer? As it is not difficult to guess, this is a device with which some measurements are performed.


But for what and who needs him, not everyone knows. So let's figure it out what a pressure gauge that he measures and shows.

As it is clear from the word structure, the pressure gauge is the measuring instrument. This word is formed from the Greek word «μάνωσις» Meaning "Looked, rarely" , and consoles "…meter" that denotes any measuring instruments. The pressure gauge is measured by loose substances - liquids and gases, or rather, their pressure.

As mentioned above, a pressure gauge is a special device that is used to measure the pressure of gases and liquids in vessels or pipelines. On the principle of work, it can be:

- piston;

- liquid;

- deformation;

- piezoelectric.

Different types Pressure gauges various device. Consider the most popular of them.

— The main part The deformation pressure gauge is the elastic element, the deformation of which leads to the deviation of the arrow indicator on the scale indicating the pressure value. As an elastic element, the springs of tubular shape, membranes are both flat and corrugated, bellows, etc. The principle of work is that the working medium affects the elastic element and deforms it, forcing it to shift in a certain direction. The leash attached to it rotates the axis with the arrow on it, shown on the scale of pressure.

- Liquid pressure gauges are used to measure the tube of a certain length filled with liquid. The working environment affects the movable tube (piston) in the tube, and to move the fluid level, it is possible to judge its pressure. Liquid pressure gauges can be single-tube and two-pipe - the second are used to determine the pressure difference of two media.

- Piston pressure gauge consists of a cylinder and the piston inserted inside. On the one hand, the pressure of the working environment or gas operates on the piston, and on the other hand, it is balanced by the load of a certain value. Move the piston due to pressure changes leads to moving the runner or arrow on the scale.


- Piezoelectric manometers use piezoelectric effect - appearance electric charge In a quartz crystal due to mechanical impact. The main advantage of these devices is the lack of inertia, which is important for controlling the rapid flow of pressure of the working medium.

Pressure gauge is one of the most widely used devices needed in any industry, where gaseous and liquid raw materials or working medium are used. They are used:

- in chemical industrywhere it is very important to know the pressure of substances involved in the processes;

- in mechanical engineering, especially when using hydrodynamic and hydromechanical nodes;

- in the automotive industry and aircraft construction, as well as in the repair and service of automotive and aircraft technology;

- in rail transport;

- in heat engineering to measure the pressure of the coolant in the pipes;

- in the oil and gas-producing sphere;

- in medicine;

- Everywhere, where pneumatic aggregates and nodes are used.

Industrial and domestic pressure gauges are produced. Appliances Used to control autonomous heating systems, motorists to measure pressure in car tires, etc.

Industrial pressure gauges are characterized by a high specialization and in some cases - a high class of accuracy.

Each manometer is assigned the corresponding accuracy class, which indicates the magnitude of the permissible error for this instrument in the pressure measurement. The smaller the number to which the accuracy class is expressed, the more accurate will be the measurement.


The most common pressure gauges with accuracy class from 4.0 to 0.5 - working devices, and from 0.2 to 0.05 - exemplary, or calibration gauges. The choice of the device with one or another class of accuracy depends on the measured object and the flowing process.

Very often in life, and especially in production, you have to deal with such a measurement device as a pressure gauge.

Manometer is a device for measuring overpressure. Due to the fact that this value may be different, the devices also have varieties. The applications of these devices are a lot. They can be applied in the metallurgical industry, in any mechanical transport, housing and communal services, agriculture, automotive and other sectors.

Types and design of the device

Depending on how purpose the instruments are used, they are divided into various types. The most common are spring pressure gauges. They have their advantages:

• Measurement of the value in a wide range.
• Good specifications.
• Reliability.
• Easy device.

In the spring pressure gauge, the sensitive element is the hollow inside the curved tube. It can have a cross section in the form of an oval or ellipsoid. This tube is deformed under pressure. It is posted on the one hand, and on the other there is a fitting, with which the amount in the medium is measured. The end of the tube, which is smeared, is connected to the transfer mechanism.

The design of the device is as follows:

• Case.
• Appliance arrows.
• Gears.
• Leash.
• Toothed sector.

Between the teeth of the sector and the gear, a special spring is installed, which is necessary in order to exclude the dead move.

The measuring scale is represented in bars or pascals. Arrow shows overpressure The environment in which the measurement is performed.

The principle of action is very simple. The pressure from the measured medium comes inside the tube. Under its exposure, the tube is trying to align, since the area of \u200b\u200bouter and internal surfaces has a different amount. The free end of the tube makes movement, and the arrow rotates at a certain angle due to the transfer mechanism. The measured value and deformation of the tube are in rectilinear dependence. That is why the value that the arrow shows, and is a pressure of a certain environment.

Varieties of pressure measurement systems

There are many different gauges for measuring low and high pressure. But they have different specifications. The main distinguishing parameter is the accuracy class. The pressure gauge will show more precisely if the value is less. The most accurate - digital devices.

In its proposal, the pressure gauges are the following types:

According to the principle of operation, such types are distinguished:

Liquid measurement systems

The value in these pressure gauges is measured by balancing the weight of the liquid pillar. Pressure measure is the level of fluid in the reporting vessels. These devices can measure the magnitude within 10-105 pa. They found their use in laboratory conditions.

In fact, this is a U-shaped tube, where there is a liquid with a large specific gravity in comparison with the liquid in which the hydrostatic pressure is directly measured. Such a liquid is most often mercury.

This category includes working and communication devices such as TV-510, TM-510. This category is most in demand. With their help, the pressure of non-aggressive and non-exclusive gases and vapors are measured. The accuracy class of these devices: 1, 1.5, 2.5. They found their use in industrial processes, during the transportation of liquids, in water supply systems and on boiler rooms.

Electro contact instruments

This category can be attributed to mananimetra and vacuum. They are meant to measure the magnitude of the gases and fluid, which in relation to brass and steel are neutral. The design in them is the same as spring. Difference only in large geometric sizes. Due to the device of contact groups, the housing of the electrocontact the device is large. This device for pressure in a controlled medium can affect the blurring / closing contacts.

Thanks to the electrocontact mechanism used, this device can be used in the alarm system.

Exemplary meters

This device is intended to verify the pressure gauges, which measure the value in the laboratory conditions. The main purpose of their purpose is to check the serviceability of the working manometers. A distinctive feature is a very high accuracy class. It is achieved thanks constructive features and gear gear in the transfer mechanism.

These devices are used in various industrial sectors for measuring the pressure of such gases as acetylene, oxygen, hydrogen, ammonia and others. It is mainly measured by a special pressure gauge can only have one type of gas. Each device indicates that gas for which it is intended. The device is also painted in the color of the gas for which it can be used. Writing I. initial Gas.

There are also vibration-resistant special pressure gauges that are capable of working with strong vibrations and a large pulsating pressure of the environment. If you use a regular pressure gauge in such conditions, it will quickly break, because the transmitter mechanism will be released. The main criterion of such devices is corrosion-resistant steel case and tightness.

Ammonia systems should be corrosion-resistant. In the manufacture of measuring mechanism of acetylene, copper alloys are not allowed. This is due to the fact that when contacting with acetylene, there is a risk of formation of acetylene explosive copper. Oxygen mechanisms must be degreasing. This is due to the fact that in some cases even a slight contact of pure oxygen and a contaminated mechanism can cause an explosion.

Safety devices

A distinctive feature of such devices is that they are capable of writing a measured pressure on the diagram, which will allow to see changes in a certain time. They found their application in industry with non-aggressive means and energy.

Ship and railway

Ship manometers are designed to measure the vacuum fluid pressure (water, diesel fuel, oils), steam and gas. Their distinguishing features are high moisture protection, resistance to vibrations and climatic influences. Apply in river and sea transport.

Railway, unlike conventional pressure gauges, the pressure is not shown, but is converted into a signal of other type (pneumatic, digital and other). For these purposes, different methods are used.

Actively such converters are used in automation systems, process control systems. But despite their destination, they are actively used in the branches of nuclear energy, chemical and oil production.

Types of measuring devices

Instruments for measuring pressure are divided into such varieties:

Most imported and domestic pressure gauges are manufactured in all common standards. For this reason, it is possible to replace one brand to another.

When choosing an instrument, it is necessary to rely on such indicators:

• The location of the fitting is axial or radial.
• The diameter of the thread of the fitting.
• The accuracy class of the device.
• Case diameter.
• Limit of measured values.

Jionic pressure gauge

Jionic pressure gauges are the most sensitive measurement devices for very small pressure. They measure it indirectly through the measurement of those ions that are formed by electron bombardment. The less gas density, the less ions will be formed. The calibration of the ionization pressure gauge is unstable. It depends on the nature of the gas that is measured. And this nature is known not always. It may be calibrated through a comparison with the values \u200b\u200bof the magnet pressure gauge, which are independent of chemistry and more stable.

Thermoelectrics with gas atoms are hung and regenerate ions. They are attracted to the electrode under the voltage, which is suitable for them (this is a suitable voltage called the collector). In the collector, the current is proportional to the ionization rate, which in the system is a pressure function. That is how the collector current measurements can be determined gas pressure.

Most ionic pressure gauges are divided into three types:

Ionic pressure gauge calibration is very sensitive to chemical composition Measured gases, structural geometry, superficial spraying and corrosion. Its unsuitable calibration can be when turned on in a very low or atmospheric pressure environment.

Measure pressure is necessary in many industrial sectors, only the devices for this use different. But regardless of this, this value is nothing but a pressure gauge is not determined.