Optical gas analysers

With the rapid development of industrial technology, the need for the use and production of various gases, which are characterised by toxicity and explosion hazards, has increased. In any plant, the monitoring of such substances is a key task to ensure its continuous and safe operation. It is also an important measure to stabilise the environmental situation.

Optical gas analysers

Gas analysis can be performed both in the laboratory using appropriate methods and with the help of modern gas analysers. The latter option is preferable because it allows the maximum accuracy in determining the concentration of a substance in the air of the working environment, and also acts as a signalling device when the indicator exceeds the norm. At the same time, portable optical gas analysers are suitable for measuring several parameters at different locations.

Description of devices

Optical gas analyser is a modern measuring equipment designed to monitor the concentration of polluting gases and gas mixtures. Devices of this category are indispensable at any enterprise where technological processes involve the use of toxic gases.

Optical gas analysers can be used to detect hydrogen sulphide (or use a specialised hydrogen sulphide gas analyser), sulphur dioxide, methane, propane, oxygen and other substances. At the same time, the devices produced by Promanalit comply with international standards and environmental requirements of the Republic of Kazakhstan. In addition, the manufacturer offers the possibility to order a modification relevant for specific operating conditions and designed to measure certain substances. The equipment can also be connected to external executive equipment (e.g. emergency ventilation system).

Technical specifications

The optical gas analyser can have from 1 to 16 measuring channels. This makes it a multifunctional device, which is suitable for technological processes using different gases. The following characteristics of modern analysers can also be highlighted:

• reading ranges - from 0 to 150 mg/m3;
• parameters of substance concentration measurement - from 20 to 120 mg/m3;
• relative error of received data - 20%;
• alarm threshold - 20, 100 mg/m3;
• temperature mode - from -45 to +45 degrees;
• integration with external equipment - relay and current analogue outputs (from 0 to 5 mA, from 4 to 20 mA);
• explosion protection - fireproof properties depend on modification.

The multi-channel optical gas analyser is equipped with a liquid crystal display, which provides information on the percentage of certain substances, as well as critical excess of a particular gas. 

Each instrument has an LED indication, which is duplicated by audible signals. If the values set by the company are exceeded, an alarm is triggered and relay contacts are closed for external enforcement. The use of optical gas analysers implies minimal operator involvement. At the same time, personnel can monitor all relevant measurements on a personal computer connected via an output interface.

Area of use

The main purpose of optical gas analysers is to monitor air conditions in small enclosed spaces. But such devices can also be used in open areas. In this case, the equipment is indispensable for various technological processes:

• steel production in metallurgical plants;
• detection of gas plant depressurisation;
• production of building materials, in particular glass and ceramics;
• air monitoring in facilities with open flames;
• work in basements, sewers, wells and other underground spaces;
• measuring the concentration of gases produced by fermentation in biotechnological processes;
• detection of fire and smoke in enclosed spaces; detection of fire and smoke in enclosed spaces; detection of fire and smoke in enclosed spaces; and detection of fire and smoke in enclosed spaces.

Principle of action

The principle of operation of all gas analysers of this type is based on the measurement of the optical properties of the substance under investigation (e.g. refractive index and spectral density). The types of sensing elements (sensors) are determined by the gases or mixtures to be monitored. The most popular are the following groups of optical gas analysers: infrared, ultraviolet, photocolorimetric, luminescent.

Features

Optical gas analysers are characterised by their high resolution, which makes them effective in analysing microconcentrations of harmful and explosive impurities in the gases in use. At the same time, the multichannel instrument assumes the possibility of combined measurement with the help of an optical module and a sensor installed in accordance with the substance under study. The equipment allows the real-time study of several parameters.

Among other advantages of modern portable analysers - high accuracy of measurements, the possibility of connecting external executive equipment, compact size. The devices also do not need frequent maintenance, regular calibration is enough.

Thus, gas analysis is an important safety measure in many companies. The quantitative contents of certain substances obtained from the measurement are used to control the process in order to optimise it. In addition, the regular use of an optical gas analyser helps to protect personnel and minimise environmental damage.