Application of Calibration Gas

A Calibration gas mixture consists of one or more gases combined in a balance gas. The choices of combinations are innumerable and it is therefore impossible to provide a complete overview of all the mixtures which can be produced.

These gas mixtures are mainly used within three main areas:

• For Auxiliary & Analytical purposes
• For Industrial processes
• For Medical use

Process analysis

Process analysis can be performed as inline or online analysis with automatic sampling, analysis and calibration. Alternatively, samples can be extracted manually from the process flows and analysed in laboratories. Advanced instrumentation such as GC, IR and MS are common today for process analysis and the requirements for calibration gases and liquids are just relevant irrespective of whether the samples are analysed manually or automatically. Examples of process which require calibration mixtures are the petrochemical industry, oil and gas production , ammonia plants , paper and pulp industry and metallurgic process.

As the requirement for calibration gases and liquids for the process industry can vary and the total number of mixtures is practically innumerable, most mixtures are produced to customer specifications. Vadilal has a comprehensive supply program for gas and liquid standards, and there are also facilities for storage of certain mixtures in order to ensure total security for continual supply.

Explosimeter Control

Combustible gases combined with air can produce explosive mixtures in conditions. The lowest concentration is defined as LEL (Lower Explosion Limit), and the highest concentration as UEL (Upper explosion Limit). Exposimeters are used to monitor the concentration of combustible components in the atmosphere where there is a potential for leakage, e.g. ships, drilling rigs, mines, workshops and industrial sites. These detectors are calibrated with a calibration gas (typically 50% LEL of the combustible component in the air) An alarm is activated when the concentration of combustible gas in the atmosphere exceeds this lelve.

Moisture analysis (H₂0)

Vadilal can supply stable calibration gases with certified concentrations of moisture (H₂O(g)) as low as 1 ppm – (76 0C dew pnt.) in a balance gas (typically nitrogen).

A common problem with this type of mixture is the increased concentration of moisture as cylinder pressure falls.Vadilal has solver this problem by developing a special treatment of the internal surface of the cylinder, which ensures that the concentration of moisture remains stable as cylinder pressure falls. The lowest guaranteed total pressure is 10 bar. For conversion tables for dew point to ppm; see speciality gas catalogue under Technical information.

Environmental and emission measurements

The calibration gases are use for measurement of :

• Emission from combustion engines and furnaces
• Industrial discharge
• Toxic components in working environments

Vadilal produce and supplies gas mixtures on request, in accordance with customer specifications and pursuant to the authorities’ requirements.

Typical components for these type of mixtures are:

• Carbon oxides
• Sulphur components
• Nitrogen oxides
• Hydrocarbons
• Oxygen
• Hydrogen
• Ammonia

Auto emission measurements

Ever-incresing requirements for reductions in emissions of harmful compounds has led to an increased focus on the measurement of emission from cars, exhaust emission tests are now a normal part of roadworthiness tests for car, lorries and buses. For calibration of the measurement instruments used for these tests, Vadilal supplies a number of calibration gases; both standard mixtures and mixtures produced t customer requirement.

Drunk-driving test

As there is an established relationship between the alcohol concentration in the blood and on a person’s breath, drink-driving tests can be performed by measuring the concentration of alcohol on a person’s breath. This is a much easier test to perform than taking blood samples. In order to ensure reliasble results, the measurement instrument used must be calibrated with a certified gas mixture containing ethanol which corresponds to an alcohol concentration in the blood of 0.5 per mile.

Calibration gases for other limits can be produced on request.

Auxiliary gases for gas chromatography

Special gas mixtures are used as auxiliary gases for gas chromatography

Auxiliary gases for gas chromatography

Within the different spectrometry techniques, gas mixtures are used for several purposes;

Laser applications

Laser types

The most common laser systems are CO2, Nd-YAG, and excimer lasers. These laser types produce characteristic wavelengths of laser beams. The properties of the laser beams form the various laser systems will vary. Each laser type has separate requirements regarding gas composition.

The lighting industry

Vadilal supplies pure gases and gas mixtures to the lighting industry. A large range of pure gases such as Kr, Xe, Ar and Ne are available.

Lamp argon is used as fill gas in filament lamps, while rare gas compounds are used in fluorescent tubes. Rare gases are also used in halogen lamps.

Fruit ripening

In order to ripen fruit , e.g. bananas more quickly, ethylene is emitted to the air where the fruit is being stored.

Bananas can only absorb a limited amount of ethylene and it is therefore not possible to add large volumers of ethylene in order to make the process even quicker.