Gas analysers

A gas analyser is an instrument that measures the concentration of one or more target gases in a sample, reporting the result as a percentage, a parts-per-million reading, or a partial pressure. It is used in combustion monitoring, emissions testing, process control and ambient air quality work.

The term covers any instrument that quantifies specific gases in a stream or sample rather than simply detecting their presence. The name says nothing about the detection method, which varies from electrochemical cells to infrared absorption to column separation.

The sensing method depends on the target gas: electrochemical cells react with oxygen and toxic gases, infrared absorption reads carbon dioxide and hydrocarbons, paramagnetic sensing measures oxygen, and chromatographs separate a mixture on a column and read the components in sequence. The instrument converts the sensor response into a concentration reading.

The listings here include bench gas analyzers for fixed sampling points, portable gas analyzers carried to the measurement, environmental monitoring equipment built for ambient concentrations and long unattended runs, and gas chromatographs that resolve complex mixtures. The choice follows the target gas and whether the instrument stays in one place or travels.

Common uses are combustion and flue monitoring, emissions testing, process control on a line, and ambient air quality. The chromatograph types extend into life sciences for separating and quantifying volatile compounds, and environmental monitoring instruments track carbon dioxide and oxygen exchange in bioprocessing off-gas.

Start from the target gas and the concentration range it must read, since a percent-level oxygen analyser will not resolve trace parts-per-million and a trace analyser saturates in a high-concentration stream. Confirm the gas list, the measuring range for each, and the sensing principle before looking at anything else.

A used unit is sold in its existing condition, while a refurbished one has been checked and brought back toward working specification before listing. For either, verify the sensor history and recalibrate against certified gas after delivery, since that is the part that ages regardless of label.

Prices here run from EUR 86 to EUR 14.000, averaging EUR 1.302. The low end covers single-sensor portable units and the high end multi-gas process benches with sample conditioning and chromatograph systems.

Servomex, Vaisala, Environmental Sciences, ATI and Dräger account for much of what is listed. Servomex and ATI are long-established in process and oxygen analysis, and Vaisala's measurement modules are widely deployed, which makes a given model straightforward to compare against others of its class.

A warranty is often possible and is arranged in consultation for the specific listing. Check the individual listing for what it states, since terms are not set centrally.

Parts can be sourced via Questpair. For established process and oxygen brands such as Servomex and ATI, sensor replacements and documentation tend to be findable.

The chassis often outlasts the sensor, which is the component that ages: electrochemical cells have a finite life and lose sensitivity whether or not the instrument has run, infrared sources drift over time, and paramagnetic cells are robust but react to vibration. The practical lifespan depends on how often the cell is replaced and recalibrated.

Used and refurbished units are listed below the price of the equivalent new instrument, which is what makes the second-hand route fit a constrained budget. Weigh the two against the specific listing and recall that warranty is arranged in consultation rather than set centrally.

The listings come from verified suppliers and distributors across 9 countries, gathered in the Questpair catalogue. You can compare new, used and refurbished units in one place across 11 suppliers.

Lead time and shipping depend on the individual seller and the unit's location, so they are set per listing rather than centrally. For a specific timeframe, contact Questpair through the listing and specialists respond within 1 hour.

Recalibration against certified gas is the first task after delivery regardless of what the seller reports, and a unit that cannot be spanned against a known concentration tells you nothing reliable. Ongoing maintenance centres on the sensor: track cell age, span and zero checks, and replacement intervals.

Bench analyzers suit a fixed process line where a conditioned stream is drawn in continuously, while a field technician reaches for a portable gas analyzer carried to the measurement. Environmental monitoring instruments serve ambient work and long unattended runs, and a lab reaches for a gas chromatograph when a mixture has to be resolved component by component.

Servomex, Vaisala, Environmental Sciences, ATI and Dräger hold much of the catalogue, and their presence matters as a guide to what comes after purchase rather than as a badge. Recognising the maker narrows where a model sits on price and how easily it can be matched against an alternative or supplied with parts.

The bottom of the band is a single-sensor portable device with one gas channel and a battery, while the top is a multi-channel analytical instrument or chromatograph with sample conditioning. Channel count, sensing principle and the presence of a conditioning system account for the distance between EUR 86 and EUR 14.000.