--- title: What Samples an Analyser Cannot Take: Know the Limits url: https://www.sarveshanalytics.com/learn/what-samples-an-analyser-cannot-take.html description: The sample limits of standard gas analysers and conditioning systems: corrosive, toxic, flammable, wet, oily and dusty gases, and how to find out before you order. updated: 2026-11-02 source: html --- Learn · Sampling and conditioning # What samples an analyser cannot take, and how to find out early Every analyser has a sample envelope. The cheapest moment to find out you are outside it is on paper. Intermediate 3 min read Lesson 9 of 10[Sampling and conditioning](https://www.sarveshanalytics.com/learn/track-sampling.html) Helpful first: [How to design a gas sample handling system](https://www.sarveshanalytics.com/learn/how-to-design-a-gas-sample-handling-system.html) Quick answer Standard ACCURRA-S analysers expect a non-corrosive, non-toxic, non-flammable, non-condensing and dry sample, free of oil, at 2 to 10 psig and about 1 LPM, with dust below 3 micron. i-Cons and SGI-320 exclude corrosive and toxic samples; SGI-320 excludes HCl, HF and H2S. Samples outside these limits need conditioning, a different product or a different method, decided before ordering. Updated 2 November 2026 · Figures from Sarvesh datasheets **After this lesson you can** - State the standard sample envelope - Recognise samples that fall outside it - Know the three responses: condition, choose another product, or choose another method ## The envelope | Item | Standard ACCURRA-S sample | |---|---| | Composition | Non-corrosive, non-toxic, non-flammable | | State | Dry, non-condensing, free of entrained oil | | Pressure | 2 to 10 psig, regulated externally | | Flow | About 1 LPM | | Particulates | Dust below 3 micron | The i-Cons and SGI-320 sample systems exclude corrosive and toxic samples, and SGI-320 specifically excludes HCl, HF and H2S, with SO2, NO and CO below 1000 ppm. See [smart-systems-for-gas-analyser](https://www.sarveshanalytics.com/smart-systems-for-gas-analyser.html). ## Samples that fall outside - **Corrosive or toxic gases:** H2S, Cl2, HCl, HF, NH3 and similar. - **Flammable samples** in the safe-area enclosure: use a hazardous-area analyser and review the sample path. - **Wet or condensing samples** straight from a process, such as raw biogas. - **Oily or tarry samples** from compressors, gasifiers or coke ovens. - **Heavily dusty samples** beyond filter capacity. - **Multi-component syngas ratios**, which are a gas chromatograph job. **Good to know** Moisture below the lowest ceramic sensor range, ambient-air quality monitoring, personal gas detection, dissolved oxygen in liquids and ppb-level fab gases are outside what these analysers do. ## Three responses 1. **Condition the sample** with coolers, filters, scrubbers, heated lines and probes until it meets the envelope. 2. **Choose a different product,** such as a hazardous-area analyser or an in-situ analyser, that is built for the conditions. 3. **Choose a different method,** such as a chromatograph, when the measurement is not one of ours. The application data sheet captures the information needed to choose among these: [The application data sheet: what to send Sarvesh](https://www.sarveshanalytics.com/learn/the-application-data-sheet-and-what-to-send-us.html). ## Why we say no early A system installed outside its envelope may run for weeks and then fail expensively. We would rather tell you at the quotation stage that your stream carries H2S than see a cell poisoned. If you are unsure whether your sample is inside the envelope, send the composition, pressure and temperature. **In short** - Know the standard sample envelope: dry, clean, non-corrosive, non-toxic, non-flammable, 2 to 10 psig, about 1 LPM. - H2S, HCl, HF, NH3, wet and oily streams are outside it. - Respond by conditioning, choosing another product, or choosing another method. - Check on paper before ordering. ## Check your understanding Answer in your head or on paper first, then open the answer. Recalling an answer teaches more than rereading. **What sample pressure does ACCURRA-S accept?** 2 to 10 psig, regulated externally. **Which gases does SGI-320 exclude?** HCl, HF and H2S. **Name two ways to handle a wet sample.** Cool it to a fixed dew point with a Peltier cooler and drain the condensate, or choose a hot-wet extractive arrangement. ## Key terms - [Sample handling system](https://www.sarveshanalytics.com/learn/glossary.html#t-sample-handling-system) - [Scrubber](https://www.sarveshanalytics.com/learn/glossary.html#t-scrubber) - [Condensate](https://www.sarveshanalytics.com/learn/glossary.html#t-condensate) - [Probe](https://www.sarveshanalytics.com/learn/glossary.html#t-probe) ## Frequently asked questions **Can ACCURRA-S measure corrosive gases?** Not in the standard configuration. Send the stream composition and we will advise. **Can you analyse H2S?** No; H2S is outside the ACCURRA-S gas list and the i-Cons and SGI-320 limits. **Can I put an analyser on raw biogas?** Only after conditioning; moisture and H2S must be dealt with first. **How do I find out if my sample is suitable?** Send the gas composition, pressure, temperature, dust and moisture with an application data sheet. ## Related products [ ### ACCURRA-S Online analyser for trace, percent and purity O2, CO, CO2, CH4 and dew point; can measure two gases from one sample. View ACCURRA-S ](https://www.sarveshanalytics.com/safe-gas-analyser.html)[ ### i-Cons Smart Peltier sample conditioner with diagnostics, auto blowback and Modbus, in a compact 19 inch cabinet. View i-Cons ](https://www.sarveshanalytics.com/smart-systems-for-gas-analyser.html)[ ### SGI-300 / SGI-320 Peltier sample cooler with integrated pump, filter and condensate detector; SGI-320 for emission monitoring. View SGI-300 / SGI-320 ](https://www.sarveshanalytics.com/sample-coolers.html) ## Where this applies - [Biogas and compressed biogas (CBG)](https://www.sarveshanalytics.com/applications/biogas-and-cbg-methane-co2-analysis.html) ## Where to go next - [How to specify a gas analyser: A practical checklist](https://www.sarveshanalytics.com/learn/how-to-specify-a-gas-analyser.html)