Analysis of gaseous media is a mandatory activity in chemical production facilities, as well as in many industrial enterprises. Such studies are procedures for measuring one or another component in a gas mixture. For example, in mining enterprises, knowledge of the characteristics of the air in a mine is a safety issue, and environmentalists thus determine the concentration of harmful elements. Such analyzes are not often used for domestic purposes, but if such a task arises, it is best to use a gas analyzer. This is a measuring device that allows you to determine the composition of the gas mixture. At the same time, there are many varieties of this device, which have fundamental differences.
Gas analyzer device
Despite the many design variations of the device, there is a set of basic components that are present in each model. First of all, this is the housing, which contains all the working elements of the gas analyzer. The fact is that such devices require high degree protection, therefore serious requirements must be placed on the outer shell. Almost every device requires power supply - accordingly, the battery can also be considered as an essential part of the device. Next we should move on to a more critical component. This is the primary transducer, that is, the gas analyzer sensor or sensing element that provides direct data for measurement.
It must be said that there are several types of such sensors, including thermocatalytic, infrared and electrochemical. The task of this element is to convert the desired component of the gas composition into an electrical signal. After this, a measuring and indicating device comes into operation, which processes this signal and demonstrates its indicators in the form of an indication or display. Now it’s worth considering the types of existing gas analyzers.
Thermochemical models
Devices of this type provide a measurement principle by determining thermal effect from a chemical reaction involving the desired component. As a rule, the oxygen oxidation technique is used in the process. Therefore, such a device can be considered as an oxygen gas analyzer, and the function of catalysts is performed by hopcalite, which is applied to a porous carrier. Measurement of oxidation indicators is carried out using metal or semiconductor thermistors. In some cases, the surface of platinum thermistors also acts as a catalyst. Typically, thermochemical models are used to work with flammable gases and vapors, as well as in the process. It can be used to determine, for example, the oxygen content of hydrogen.
Magnetic devices
IN in this case We are also talking about devices focused on the determination of oxygen. A gas analyzer of this type monitors the susceptibility of magnets relative to the medium under study depending on the oxygen concentration in it. It would seem that this component can be determined by other types of device, but there is one feature. The fact is that a magnetic gas analyzer is a meter that is capable of more high accuracy determine concentration in complex mixtures. It is also necessary to distinguish between magnetomechanical and thermomagnetic devices. In the first case, the device measures the force acting in a non-uniform magnetic field on a sensitive element placed in the medium under study - for example, a rotor. The readings will depend on the medium temperature and pressure. The operating principle of thermomagnetic models is based on a convention that arises when a gas mixture interacts with inhomogeneous temperature and magnetic fields.
Pneumatic models
Such devices operate based on measuring viscosity and density. To do this, data on the hydromechanical properties of the flow are analyzed. It must be said right away that there are three options for such devices: throttle, jet and pneumoacoustic. A throttle gas analyzer is a device with a converter that measures when a gas mixture passes through it. Jet-type models measure dynamic characteristics pressure of the gas mixture flowing from the nozzle. Typically, devices of this type are used when working with nitrogen and chloride compounds.
The pneumoacoustic device includes two whistles with approximately equal frequencies about 4 kHz. The first whistle passes the analyzed gas through itself, and the second - the composition for comparison. As a result, the air gas analyzer allows you to compare vibration frequencies, converting the indicators into pneumatic vibrations using an amplifier. A type is used to ensure the signal is supplied.
Infrared models
The operating principle of such gas analyzers is based on the selective absorption of vapor and gas molecules by infrared radiation. It is important to consider that the device provides for the absorption of those gas mixtures whose molecules contain at least two different atoms. The specificity of molecular spectra in various gases also determines the increased selectivity of such devices. For example, there are regular and dispersive versions of the converter. A dispersive gas analyzer is a device that uses radiation generated by monochromators, that is, prisms. Conventional representatives of this class use non-monochromatic radiation, provided due to the features of optical circuits. For this purpose, light filters, special radiation receivers and other components are used. Also, infrared gas analyzers can use non-selective radiation detectors - in particular, thermopiles, bolometers and semiconductor components.
How to use the device?
It is important for the user of the device to become familiar with the display or other information output device included with the device. As a rule, modern displays display the date, as well as several fields for data on the composition of the gas mixture. The instructions for the gas analyzer in a specific configuration will allow you to obtain complete information about the meaning of the fields and channels of the device. Actually, control of the device’s functions also depends on the specific model. As a rule, it is sufficient to activate the device while in a gaseous environment. Next, when the threshold concentrations of the desired component are reached, the device will give a signal. In some models, light indication is also possible. At the same moment, the main lines about chemical composition gas mixture and the properties of a specific component for which the device was configured.
Device verification
Like any gas analyzer it needs verification. This procedure will allow you to evaluate technical condition, device performance, and compliance. Portable gas analyzers are the most likely to suffer from performance problems, so they should be serviced more frequently. So, how is verification carried out? The procedure is performed on a special testing stand. It begins with inspecting the device, testing the replacement of faulty elements. This is followed by calibration activities and making the necessary settings.
Direct verification involves the use of a device to assess the concentration of a certain component in a compressed gas cylinder. That is, special mixtures are used, with the help of which gas analyzers are checked for analysis of a specific component.
Heating using fuel-burning units is convenient, economical and efficient. Leakage of flammable gas or combustion products is undesirable when using the boiler.
A household gas alarm (or sensor) is a device that monitors the quality of ambient air in a boiler room. In case of accumulation of dangerous concentrations harmful substances in the air, the alarm is triggered: it turns on the sound and light alarm, turns off the gas supply and stops the combustion of fuel in the boiler.
Installing such a sensor will protect owners from gas accumulation in the room and help eliminate leaks in a timely manner.
The signaling device can send a signal to mobile phone(if you have a GSM module and connect it to the subscriber number).
Gas alarms are installed in rooms where accumulation of harmful substances is possible. Traditional gas analyzers are capable of detecting the accumulation of carbon monoxide, propane and natural gas(methane).
Carbon monoxide (CO) is a substance released during the combustion of fuel, and its leakage in an enclosed area can be deadly.
Methane (CH4) is the main element of natural gas, which is supplied through a central gas pipeline. If it accumulates, an explosion and fire can occur (even from the smallest spark).
Propane (C3H8) is the main element of a liquefied propane-butane mixture, which is heavier than air, so even with an open window, gas may accumulate in the lower part of the room.
Design and principle of operation of gas alarms
The operation of gas alarms is based on various sensors: thermomechanical, optical or electromechanical. All gas analyzers consist of certain elements:
- The primary transducer is a sensing element that senses and calculates the gas concentration in the ambient air.
- A measuring and display module is a system that receives the signal from the primary transducer and compares it with a given value.
- The power supply is a system for providing electrical power to the device.
- Device body.
Functionality of gas alarms:
- Light and sound alarm.
- Cutting off the gas supply using a solenoid valve.
- Turning on the exhaust device.
- Sending a signal to the fire or control panel.
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Another way to heat a bathhouse is a warm floor, more about it in.
Types of gas alarms
The main difference between gas analyzers is the type of gas captured. The most common household alarms are gas analyzers for:
- carbon monoxide;
- methane;
- propane.
Combined gas analyzers capable of capturing several types of gas at once.
Fans for household alarms
One of the types of localization of the accumulation of harmful substances in the boiler room is the installation exhaust fan, which is turned on by a signal from the gas analyzer and provides forced ventilation.
Shut-off valves
An electromagnetic shut-off valve is used to instantly stop the flow of gas based on a signal from a gas analyzer. There are different valves:
- According to the diameter of the pipeline.
- Electrical.
- With permissible pressure.
- Different in design.
There are 2 types of construction: normally open and normally closed.
They have the following differences:
- A normally open valve is manually cocked and is not energized during operation. If the gas analyzer is triggered, an electrical impulse is sent to close the valve. The valve is marked “NA”;
- A normally closed solenoid valve is also manually cocked, but this requires a power supply. During operation, it is constantly under voltage, and upon a signal from the gas analyzer, the voltage disappears and the valve closes.
Cost of solenoid shut-off valve: type N.A., 220 V, Pmax: 500 mbar:
| Nominal diameter | Cost, rub. |
| Madas Dn 15 | 1490 |
| Madas Dn 20 | 1515 |
| Gross Dn 20 | 1360 |
| Madas Dn 25 | 1950 |
| Gross Dn 25 | 1470 |
Operation of gas alarms
It is better to mount gas analyzers to a vertical plane where a gas leak may occur (near a boiler, furnace, gas meter, gas water heater).
The gas analyzer should not be placed in the following places:- Close to gas burners(1m).
- In places of heavy contamination (dust, grease, ash).
- Near ventilation ducts.
- In places where paint, solvent and flammable materials are stored.
When installing the sensor, the physical properties of the gas and its density should be taken into account:
- Methane - not lower than 0.5 m from the floor.
- Carbon monoxide - at a height of 1.8 m from the floor, but not higher than 0.3 m to the ceiling.
- Propane not higher than 0.5 m from the floor.
- Combined sensor for methane and carbon monoxide - in the range of 0.5-0.3 m to the ceiling.
To ensure smooth operation solenoid valves It is necessary to install batteries with an automatic transfer system to backup power.
The gas analyzer’s passport describes all the functions and requirements for operation, and compliance with them will allow achieving reliable operation equipment.
Gas analyzer installation
No device installation required special effort, it can be secured with dowels or self-tapping screws. The device passport contains a diagram for connecting electrical power to the device and connecting it to other equipment.
Installation of solenoid valves on gas pipelines should only be carried out by a qualified specialist.Periodic inspection
At least once a year, it is necessary to inspect the performance of the gas analyzer.
The instruments used to perform gas analysis are called gas analyzers. They are manual and automatic. Among the former, the most common are chemical absorption ones, in which the components of a gas mixture are sequentially absorbed by various reagents.
Automatic gas analyzers measure any physical or physicochemical characteristic of a gas mixture or its individual components.
Currently, automatic gas analyzers are the most common. Based on their operating principle, they can be divided into three main groups:
- Devices whose operation is based on physical methods of analysis, including auxiliary chemical reactions. With the help of such gas analyzers, they determine the change in the volume or pressure of the gas mixture as a result of chemical reactions its individual components.
- Devices whose operation is based on physical methods of analysis, including auxiliary physical and chemical processes(thermochemical, electrochemical, photocolorimetric, etc.). Thermochemical ones are based on measuring the thermal effect of the reaction of catalytic oxidation (combustion) of gas. Electrochemical ones make it possible to determine the gas concentration in a mixture based on the electrical conductivity of the electrolyte that has absorbed this gas. Photocolorimetric methods are based on the change in color of certain substances when they react with the analyzed component of the gas mixture.
- Devices whose operation is based on purely physical methods of analysis (thermoconductometric, thermomagnetic, optical, etc.). Thermoconductometry is based on measuring the thermal conductivity of gases. Thermomagnetic gas analyzers are used mainly to determine the concentration of oxygen, which has high magnetic susceptibility. Optical gas analyzers are based on measuring the optical density, absorption spectra or emission spectra of a gas mixture.
Each of the mentioned methods has its pros and cons, the description of which will take a lot of time and space, and is beyond the scope of this article. Manufacturers of gas analyzers currently use almost all of the listed methods of gas analysis, but electrochemical gas analyzers are most widespread, as they are the cheapest, most versatile and simplest. Cons this method: low selectivity and measurement accuracy; short service life sensitive elements exposed to aggressive impurities.
All gas analysis instruments can also be classified:
- by functionality (indicators, leak detectors, alarms, gas analyzers);
- By design(stationary, portable, portable);
- by the number of measured components (single-component and multi-component);
- by the number of measurement channels (single-channel and multi-channel);
- for its intended purpose (to ensure work safety, to control technological processes, for control of industrial emissions, for control of automobile exhaust gases, for environmental control).
Classification by functionality.
- Indicators are devices that provide a qualitative assessment of a gas mixture based on the presence of a controlled component (according to the “many - little” principle). As a rule, information is displayed using a line of several dot indicators. All indicators are on - there is a lot of component, one is on - there is not enough. This also includes leak detectors. Using leak detectors equipped with a probe or sampler, it is possible to localize the location of a leak from a pipeline, for example, refrigerant gas.
- Alarms also provide a very rough estimate of the concentration of the controlled component, but at the same time they have one or more alarm thresholds. When the concentration reaches a threshold value, alarm elements are triggered (optical indicators, sound devices, relay contacts are switched).
- The pinnacle of the evolution of gas analysis devices (not counting the chromatographs that we are considering) is the gas analyzers themselves. These devices not only provide a quantitative assessment of the concentration of the measured component with indication of readings (by volume or mass), but can also be equipped with any auxiliary functions: threshold devices, output analog or digital signals, printers, and so on.
Classification by design.
Like most control and measuring instruments, gas analysis devices can have different weight and size indicators and operating modes. These properties determine the division of devices by design. Heavy and bulky gas analyzers, usually designed for long-term continuous operation, are stationary. Smaller products that can be easily moved from one object to another and quite simply put into operation are portable. Very small and light - portable.
Classification according to the number of measured components.
Gas analyzers can be designed to analyze multiple components at once. Moreover, the analysis can be carried out both simultaneously for all components, and one by one, depending on design features device.
Classification by the number of measurement channels.
Gas analysis devices can be either single-channel (one sensor or one sampling point) or multi-channel. As a rule, the number of measurement channels per device ranges from 1 to 16. It should be noted that modern modular gas analytical systems allow you to increase the number of measurement channels almost to infinity. Measuring components for different channels can be either the same or different, in an arbitrary set. For gas analyzers with a flow-type sensor (thermoconductometric, thermomagnetic, optical absorption), the problem of multipoint monitoring is solved using special auxiliary devices - gas distributors, which ensure alternate supply of a sample to the sensor from several sampling points.
Classification by purpose.
Unfortunately, it is impossible to create one universal gas analyzer that could be used to solve all gas analysis problems. Just as it is impossible, for example, to make one ruler to measure both fractions of a millimeter and tens of kilometers. But a gas analyzer is many times more complex meter, rather than a ruler. Different gases, in different concentration ranges, are controlled in different ways, by various methods and measurement methods. Therefore, manufacturers design and produce instruments to solve specific measurement problems. The main tasks are: atmospheric control working area(safety), control of industrial emissions (ecology), control of technological processes (technology), control of gases in water and other liquids, control of mine atmosphere, control of vehicle exhaust gases (ecology and technology). In each of these areas, even more highly specialized groups of devices can be distinguished. Or you can enlarge it, which is what we did - in our catalog you will find 5 main groups of gas analysis instruments:
- gas analyzers, gas detectors and safety systems and labor protection,
- gas analyzers and control systems for technological processes and emissions industrial enterprises,
- gas analyzers for analysis water purification,
- mine gas analyzers and mine atmosphere control systems,
- gas analyzers for engine emission control.
They are used in many areas of our life: in ecology, analysis and control systems of internal combustion engines (engines internal combustion), in industry, sometimes in residential premises, in boiler rooms and other institutions. They save many lives and allow production to be controlled. Company LLC NPO.EKO-INTEKH. supplies excellent gas analyzers at great prices!
The gas analyzer itself is a device that determines the concentration of certain gases or even their mixtures in various environments (most often in air). The very first and most common, even today, are absorption gas analyzers. Most of them are portable gas analyzers. Their principle of operation is that the components of the analyzed gas mixture are gradually absorbed by special reagents. The state of the reagents determines the qualitative and quantitative indicators of the analyzed gases.
Automatic gas analyzers are capable of analyzing a gas mixture in any environment over a long period of time. Stationary gas analyzers in various institutions belong to this type. Before you buy a gas analyzer from us, you should first decide what type of equipment you need.
1) Chemical (volumetric manometric) gas analyzers determine the characteristics of a gas mixture based on chemical reactions.
2) Thermochemical gas analyzers. The operation of such devices is based on measuring the thermal effect during the gas combustion reaction. Probably each of us has seen methane gas analyzers. So most of them work precisely on this principle.
3) Electrochemical gas analyzers. These instruments measure electrical conductivity special solution, which absorbs surrounding gases. Based on these data, the concentration, pressure and even volume of gases are determined.
4) Photometric gas analyzers are used mainly for measuring small doses of certain gases in any environment. Their operating principle is based on the fact that some substances are capable of changing their color upon contact with a particular gas mixture. The color change is detected by sensors that determine the gas concentration.
5) Thermoconductometry can be both portable and stationary gas analyzers. Their feature is the ability to analyze multicomponent gas mixtures.
6) Densimetric gas analyzers are mainly used to determine the concentration carbon dioxide in air or other gas mixture.
7) Magnetic gas analyzers are used to determine the concentration of oxygen in a gas mixture. This is based on the effect that oxygen is highly susceptible to the effects of magnetic fields.
