--- title: Furnace Atmosphere Gas Analysers | Sarvesh url: https://www.sarveshanalytics.com/applications/heat-treatment-furnace-atmosphere.html description: Oxygen, hydrogen, dew point, CO and CO2 analysers for carburising, annealing, galvanizing and colour-coating furnaces. Made in Pune. updated: 2026-11-02 source: html --- Steel, heat treatment and furnaces # Furnace atmosphere analysers for annealing, carburising and galvanizing The atmosphere in a furnace decides surface quality. Whether you run bright annealing in nitrogen and hydrogen, endothermic gas for carburising, or a galvanizing line, a few measurements keep the atmosphere in specification and the gas bill down: trace oxygen and dew point on one sample, hydrogen by thermal conductivity, and CO and CO2. - ISO 9001:2015, certified by TÜV - Designed and built in Pune since 2002 - Supplied to Reliance, Tata Steel, Indian Oil, Linde and ISRO Quick answer Furnace atmosphere analysis uses trace oxygen (3015, 0 to 1000 ppm), dew point (M015, minus 80 to plus 20 C), hydrogen in nitrogen (ACCURRA-TCD), and CO and CO2. A dual-channel ACCURRA-S reads oxygen and dew point from one sample. Updated 2 November 2026 · Figures from Sarvesh datasheets ## The measurement and why it matters Four measurements cover most heat treatment atmospheres. Trace oxygen, from ACCURRA-S 3015 at 0 to 1000 ppm, shows leaks and air ingress. Dew point, from M015 at minus 80 to plus 20 C, shows moisture. Hydrogen in nitrogen, from ACCURRA-TCD, shows the reducing component. CO and CO2, by NDIR and electrochemical sensors, characterise carbon-bearing atmospheres. ACCURRA-S can combine two of these in one enclosure. The dual-channel 3015 plus M015 reads oxygen in ppm and dew point from one sample. Each channel has its own electronics, outputs and Modbus address. Hot furnace gas needs a probe and cooler sized to the sample. Atmospheres with hydrogen and CO are flammable, so the conditioning must suit the area classification, and the standard ACCURRA-S sample specification asks for a non-flammable, dry sample; we review these streams case by case. ## Models and ranges | Model | Measures | Range | Sensor and notes | |---|---|---|---| | 3015 | Trace oxygen | 0 to 1000 ppm | Electrochemical | | M015 | Dew point | -80 to +20 C | Ceramic sensor | | ACCURRA-TCD | Hydrogen in nitrogen | Binary | Thermal conductivity | | 2015 / 2030, 6015 / 6030 | CO and CO2 | ppm and percent | Electrochemical and NDIR | | ACCURRA-Zr | Percent O2 in combustion zones | Up to 1400 C probe option | Zirconia, in-situ | ## Process notes ### Annealing furnaces Bright annealing heat-treats stainless steel, copper and other metals in a protective atmosphere so that surfaces stay clean. Nitrogen with a few percent hydrogen is common, and the atmosphere has to stay very low in oxygen and moisture or the work discolours. Three readings tell you the state of the furnace: trace oxygen at the exit, hydrogen percentage in the mix, and dew point. Together they show leaks, a failing gas supply or a wet muffle. Using the hydrogen reading to trim hydrogen flow can cut gas use, which is a real operating cost. Give us the gas mix, the furnace type and the sample point. For hydrogen in nitrogen, ACCURRA-TCD works as a binary measurement. For oxygen at ppm level, keep the sample line short and tight, since a small leak raises the reading. Verify zero with pure nitrogen and span with a certified oxygen-in-nitrogen mix. ### Carburizing furnaces Carburizing adds carbon to the surface of low-carbon steel at around 900 C, so that the part hardens after quenching. The atmosphere is usually endothermic gas, a mixture of nitrogen, hydrogen and carbon monoxide made from natural gas or propane and air, with additions to adjust carbon potential. Carbon potential follows from the balance between CO, CO2, CH4 and water vapour, so analysers that read those gases give a second opinion on a probe-based control loop. Sooting and tar in the atmosphere affect sample lines, so the gas is cooled and filtered before analysis. Atmosphere samples may carry soot and water. Pull the sample through a heated filter, cool it to condense water, and protect the NDIR cells from carry-over with a membrane filter. Calibrate with certified CO, CO2 and CH4 span gases at points near your operating values, and check zero with nitrogen. ### Galvanizing and colour coating On a continuous galvanizing line, steel strip passes through an annealing furnace with a nitrogen-hydrogen atmosphere that reduces surface oxide before it enters the zinc bath. Colour coating lines use furnaces to cure paint and need controlled combustion. In the protective zone, low oxygen and low dew point decide coating adhesion, so trace oxygen, hydrogen and dew point analysers read from several furnace sections. In the combustion zones, an in-situ zirconia analyser like ACCURRA-Zr reads percent oxygen in flue gas to control burner air. Match the analyser to the zone. In the protective atmosphere zone use trace oxygen and dew point analysers with cooled samples, and add hydrogen by thermal conductivity if the mix needs control. In combustion zones, install ACCURRA-Zr with air calibration. Tell us how many zones you want to measure, and whether one analyser should switch between them. ## Sampling and installation - Hot furnace gas needs a probe and cooler sized to the sample. - Atmospheres with hydrogen and CO are flammable, so the conditioning system must suit the area classification. - Use heated probes in Inconel or ceramic for hot sample points. - Keep lines short and tight; at ppm level a small leak raises the reading. ACCURRA-S sample specification: non-corrosive, non-toxic, non-flammable, non-condensing and dry, free from entrained oil; sample pressure 2 to 10 psig, regulated externally; flow about 1 LPM; dust below 3 micron. Where your sample differs, we design conditioning around it. ## Send us your process data **What the data sheet asks for** Send what you have and we will ask for the rest. - The gases to measure, the range, and the accuracy you need - Background gases and their typical composition - Sample temperature, pressure and dew point at the tapping point - Dust level, and whether the gas carries tar, oil or condensable vapour - Process connection and, for ducts, the duct diameter - Where the sample vents to, and at what pressure - Area classification of the tapping point and of the analyser location, and the IP protection needed - Distance between the tapping point and the analyser - Outputs you need: 4-20 mA, dual range, relays, Modbus RTU - Calibration approach, calibration gas available, and whether blowback is required - Utilities at site: power supply, instrument air, nitrogen, steam and cooling water, and the ambient temperature range - The atmosphere gas mix, furnace type and sample point temperature ## Recommended Sarvesh products [ ### ACCURRA-S 3015 and M015 on one sample, and CO and CO2. View ACCURRA-S ](https://www.sarveshanalytics.com/safe-gas-analyser.html)[ ### ACCURRA-TCD Hydrogen in nitrogen. View ACCURRA-TCD ](https://www.sarveshanalytics.com/binary-tcd-thermal-conductivity-analysers.html)[ ### ACCURRA-Zr Combustion zones. View ACCURRA-Zr ](https://www.sarveshanalytics.com/flue-gas-analysers.html)[ ### SP and SRP sample probes Heated and high-temperature probes. View SP and SRP sample probes ](https://www.sarveshanalytics.com/sample-probes.html) ## Frequently asked questions **What do I measure in a heat treatment furnace?** Typically trace oxygen, hydrogen percentage and dew point for protective atmospheres, and CO, CO2 and methane for carbon-bearing ones. **Can one analyser read oxygen and dew point?** Yes. The dual-channel 3015 plus M015 reads both from one sample. **Can the analyser output to the furnace controller?** Yes. Isolated 4-20 mA with user-configurable and dual range, relay alarms and Modbus RTU are standard on ACCURRA-S. **Which analyser for combustion zones?** ACCURRA-Zr, in-situ, calibrated on air. ## More in Steel, heat treatment and furnaces - [Steel plant process gases](https://www.sarveshanalytics.com/applications/steel-plant-process-gas-analysis.html) - [Float glass bath atmosphere](https://www.sarveshanalytics.com/applications/float-glass-bath-and-furnace-atmosphere.html) - [Cold rolling mill furnaces](https://www.sarveshanalytics.com/applications/cold-rolling-mill-furnace-atmosphere.html) - [Powder metallurgy and metal injection moulding sintering](https://www.sarveshanalytics.com/applications/powder-metallurgy-and-metal-injection-moulding-sintering.html) - [Aluminium controlled-atmosphere brazing furnaces](https://www.sarveshanalytics.com/applications/aluminium-controlled-atmosphere-brazing-furnaces.html) - [Bright annealing of copper tube, stainless steel and wire](https://www.sarveshanalytics.com/applications/bright-annealing-of-copper-tube-stainless-steel-and-wire.html) - [Carburising and endothermic gas carbon potential](https://www.sarveshanalytics.com/applications/carburising-and-endothermic-gas-carbon-potential.html) - [Continuous annealing and galvanising line atmospheres (HNX)](https://www.sarveshanalytics.com/applications/continuous-annealing-and-galvanising-line-atmospheres-hnx.html) - [Foundry cupola and melting furnace gas](https://www.sarveshanalytics.com/applications/foundry-cupola-and-melting-furnace-gas.html) - [**All steel, heat treatment and furnaces applications**](https://www.sarveshanalytics.com/industries/steel-metals-heat-treatment-gas-analysers.html) - [Browse analysers by gas](https://www.sarveshanalytics.com/gas-analyser.html)