The device and diagram of the gas analyzer.

Gas analyzer design and circuit.

Design and circuit of the gas analyzer

A gas analyzer is a device that analyzes gas mixtures in the air to determine their qualitative and quantitative composition. The device helps prevent explosions of household gas.

Types of gas analyzers
Let's consider some types of gas analyzers: there are manual and automatic devices. Automatic gas analyzers are the most popular — they measure any physical or physicochemical characteristic of a gas mixture or its individual components. Among the automatic ones, there are also some types of gas analyzers, divided into several groups according to their operating principle:
1. devices operating on the basis of physical methods of analysis, including auxiliary chemical reactions. Such gas analyzers determine the change in volume or pressure of a gas mixture as a result of chemical reactions of its individual components;
2. devices operating on the physical basis of analysis, including auxiliary physical and chemical processes (thermochemical, electrochemical, photocolorimetric). Thermochemical are based on measuring the thermal effect of the reaction of catalytic oxidation (combustion) of gas. Electrochemical ones allow determining the concentration of gas in a mixture by the value of the electrical conductivity of the electrolyte that has absorbed this gas. Photocolorimetric ones are based on the change in color of certain substances when they react with the analyzed component of the gas mixture.
3. devices that use exclusively physical methods of analysis (thermoconductometric, thermomagnetic, optical). Thermoconductometric methods are based on measuring the thermal conductivity of gases. Thermomagnetic gas analyzers are used mainly to determine the concentration of oxygen, which has a high magnetic susceptibility. Optical types of gas analyzers are based on measuring the optical density, absorption spectra, or emission spectra of a gas mixture.
By function, there are: indicators, leak detectors, alarms, gas analyzers. Indicators provide a qualitative assessment of the gas mixture by the presence of the controlled component, presenting information by means of a line of several point indicators. Alarms also provide an approximate assessment of the concentration of the controlled component, but at the same time have one or several alarm thresholds. Gas analyzers themselves provide a quantitative assessment of the concentration of the measured component with indication of readings, and can also be supplemented with auxiliary functions.
By design, gas analyzers are divided into stationary, portable, handheld; by the number of measured components — single-component and multi-component; by the number of measurement channels — single-channel and multi-channel; by purpose — to ensure work safety, to control technological processes, to control industrial emissions, to control vehicle exhaust gases, for environmental monitoring.

Gas analyzer diagram
The diagram of the gas analyzer is necessary when installing the equipment. Each gas analyzer has its own diagram, which depends on the operating principle of a particular device. From this point of view, gas analyzers are pneumatic, electrochemical, magnetic, semiconductor, etc. Gas analyzer diagramincludes general designations: R0 and — potentiometers; R1 and R3 — thermistors for operation; R2 and R4 — thermistors for comparison; voltage source, which was stabilized; secondary device.
Thermochemical gas analyzers are used to determine the thermal effect of a chemical reaction in which a specific element participates. Usually, oxidation of a given component with atmospheric oxygen is used; catalysts — finely dispersed Pt, which is applied to the surface of a porous carrier or manganese-copper (hopcalite).Scheme of a gas analyzer thermochemical:
 
1 — voltage source (stabilized);
2 – secondary device;
R2 and R3 – thermistors for operation and for comparison;
R1 and R4 – constant resistors.
The circuit diagram of any type of gas analyzer can be similar to the one presented, the differences lie in the details that are important during installation. The operating principle of the gas sensor is also based on this.