Close this search box.
Close this search box.


Mixing or Diluting Gases for Multipoint Calibrations

Designed and produced by AlyTech and distributed by CAC Gas & Instrumentation, GasMix™ products enable multipoint gas calibrations by mixing and/or diluting several calibration gases.

GasMix™ provides an on-site Gas Standard Preparation System for analytical laboratories that need to prepare gas standards for all kinds of analytical instruments including Gas Chromatography and Gas Spectroscopy systems; Refinery Gas Analysers; On-line Gas Analysers and more.

The GasMix™ software is fully automated allowing the option to run a single injection or a fully automated and pre-programmed sequence. The GasMix™ Software can be remotely controlled to drive an external injection valve and/or the Start command of an analyser.

 Using GasMix™ provides the following benefits:

  • Reducing the number of standard gas cylinders stored.
    • More profitable and safer
  • Multiple gas standards can be created.
  • Adaptation to all your gas analysis instruments
    • Being modular, it is a unique and universal gas sampler and injector.
  • Drastically reduces operator bench time.


The GasMix™ products can be used in a variety of industry applications including petrochemical, environmental, research & development, oil & gas, pharmaceuticals, and specialty gases. Below we discuss in further detail 2 of those applications.


Environmental Applications

Environment protection is one of the issues of this century. Many laboratories therefore conduct analyses of air emissions in order to meet environmental standards. To do so they need efficient and accurate analysers.

Being able to create standards according to the current application gives more flexibility to the user. Environmental standards such as EN 14212 (Standard method for the measurement of sulfur dioxide concentration by UV fluorescence) require multipoint calibration. Gas standards are expensive and certain gas mixtures require a long time to be obtained. These new conditions have created a demand for mixers producing accurate gas concentrations. GasMix™ meets these new requirements. Its accuracy allows the user to produce optimal mixes, even at low concentrations. GasMix™ reduces gas consumption, the operator time is decreased by its automation and the GasMix™ software helps with inventory management.

Application examples:

GasMix™: monitoring the performance of environmental analysers.

Calibration of SO2, NO-NOX & CO analysers.

The linearity and repeatability of a French air quality monitoring agency for SO2 NO-NOx and CO analysers are periodically assessed.

The tests are performed with a GasMix™ Aiolos dilutor. Automatic sequences were configured on the GasMix™ user interface.

These sequences are used to assess the analysers linearity on their six concentrations (80%, 40%, 0%, 60%, 20% and 95%) measuring range, and their repeatability at three concentration levels (zero, 95 % and the national calibration concentration). The measurements are performed in accordance with the methods specified in the NF EN 14212, EN 14211 and NF EN 14626 standards. Linearity residuals are calculated from “real“ concentrations generated, not the one calculated from the calibration curve. This implies the dilutor calibration for all the generated concentrations.

alytech blog 1.png

alytech blog 2.png

LiqMix : Biogas valorisation

The biogas produced by landfills and sewage digesters, is an excellent source of renewable energy for electricity production. The composition of the biogas produced by these methods is complex and traces of silica compounds are present. But this type of compounds is prohibited in many applications using biogas as fuel. As a matter of fact, at high temperature, siloxanes are transformed into silicon oxide and corrode the metal surfaces of an engine. It is therefore necessary to offer purification processes that are technically efficient and economically viable.

To assess the ability of some activated carbon to remove siloxanes and hydrogen sulphide in the biogas, one of our customers uses a gas chromatograph. This instrument needs to be calibrated but the gaseous standards siloxanes are not easily obtainable. LiqMix™ is used to generate a standard gas from a liquid standard of octamethylcyclotetrasiloxane. This siloxane standard may optionally be mixed with an H2S standard. A trial can last several days.


Oil & Gas Applications

Whether they are control laboratories in production plants or R&D labs for the Oil & Gas industry, petroleum refineries and gas plants use many analysers (such as GCs) in their laboratories.

Those analysers must deliver accurate and reliable measurements in order to meet product specifications according to ASTM or ISO standards.

By enabling the dilution and/or mix of 2 to 16 different gases, GasMix™ is the right tool for analysts needing certified gas standards at various levels of concentrations. This includes traces which are often not stable or not available in bottles on the market.

Application examples:

Automatic multipoint calibration of GC

One refinery customer from the Gulf region has ordered an analyser based on the UOP 603 method. This method involves the analysis of carbon monoxide, carbon dioxide and methane at trace levels in light hydrocarbon gaseous fractions. The analyser is fitted with a methanizer which converts the carbon oxides into methane, which itself is detected by a FID detector.

The customer has one certified gas standard whose concentration for each compound is around 10 ppm, and one must verify that the analyser can quantify down to 40 ppb.

A GasMix™ dilutor model Zephyr, fitted for aggressive gases, is installed between the gas cylinder and the GC. A sequence involving 5 different concentrations, 2 replicates per level, is built up. Each of these solutions is flown into the analyser for 2 minutes to purge the lines and take the possible adsorption phenomenon in account. The automatic sequence of Zephyr turns all gas flows down to zero once the sample has been injected, and remains that way during the remaining time of the GC run.

The use of the dilutor allowed the verification that the methanizer was performing well as well as verifying the linearity of the detector’s response. Additionally, and this is an essential point, we can quantify trace level analysis from calibration solutions which are close to the unknown samples (<100ppb), starting from only one calibration gas.

To complete this process without the use of the diluter would be to use several calibration gas cylinders, at least 4 or 5, whose concentration might go down to 1 ppm, not below. The supply of such gases may involve some long delivery times and can be expensive. Zephyr allows us to reach low levels (50 ppb and above in this case) using an unlimited number of points, and at a much lower cost. Zephyr can also then be used for other analysers and with other gases.

LPG dilution with Aura

A Liquefied Petroleum Gas (LPG) is a mixture of light hydrocarbon gases and is prepared by refining petroleum or “wet” natural gas. It is almost entirely derived from fossil fuel sources, being manufactured during the refining of petroleum (crude oil), or is extracted from petroleum or natural gas streams as they emerge from the ground. These gases are mostly propane, butane or a mix of both.

LPG will evaporate quickly at normal temperature and pressure. It is usually supplied in pressurized steel vessels for transportation and commercialization.

LPG is a mixed phase matrix, meaning that at atmospheric pressure, one can find at the same time liquid and gas. If a component is in a gas phase, it will not have the same behavior as being in a liquid phase or in a mixed phase.

The matrix can have a considerable effect on the way the analysis is conducted and on the quality of the results obtained; such effects are called matrix effects. The most common approach for accounting for matrix effects is to build a calibration curve using standard samples with known analyte concentration and trying to approximate the matrix of the sample as much as possible.

The AURA heats and vaporises the LPG containing the compounds of interest into GasMix™ which will then dilute it with another gas.The use of a gas mixing system with Aura allows us to check the linearity of the analyser. Using a LPG standard avoids matrix effects giving more accurate results.

GasMix™ can prepare low level standards, without limitations in the number of points, with only one LPG standard, saving time and money.


Overall Benefits

  1. Reduce the number of necessary gas standards

Components in cylinder mixtures have a fixed and defined ratio. A different ratio automatically implies a different gas cylinder. The use of the GasMix™ system provides flexibility in the laboratory. Two (or more) gas standards can be mixed with different ratios.Furthermore, different concentrations are required for a multi-point calibration. That means several gas cylinders must be purchased. GasMix™ only uses the high concentration standards and dilutes that to the needed lower concentrations.

  1. Optimizing the Efficiency of Gas Cylinders

All gas standards can be optimized to their fullest. Allowing all gas standards to be used at multiple concentrations. A higher gas concentration can be diluted down to lower levels which maximises the efficiency of the gas cylinder.

  1. Reduction of Bench Time

Manual gas injection requires lots of user intervention as there is no “automatic injector” for gas samples. GasMix™ software automates the steps that an operator has to do by creating an automated pre-programmed sequence.


Have a Question?

Request a quote

Request a quote today for our speciality gas products for your specific needs. Enjoy high quality products, competitive products & fast delivery. 

Scroll to Top