New to gas analysis

What you will be able to do

• Say what an online analyser measures and what it cannot
• Read ppm, percent and dew point without confusion
• Explain accuracy, drift and response time
• Name the main sensor technologies and when each fits
• Describe why sampling and calibration decide real-world results

Follow these lessons in order

1. What is online gas analysis? A plain introductionOnline gas analysis measures the composition of a process gas continuously, as it flows, and sends the result to a display, an alarm or a control system.The whole subject in one lesson.Beginner3 min
2. Online vs laboratory vs portable gas analysisUse an online analyser when the answer is needed continuously to control or protect a process.Why plants measure online at all.Beginner3 min
3. How gases behave: pressure, temperature and partial pressureIn a gas mixture each component contributes a partial pressure equal to its fraction times the total pressure.The physics behind most surprises.Beginner3 min
4. ppm, percent and ppb explained for gas analysisPercent, ppm and ppb are volume fractions: 1 % equals 10,000 ppm, and 1 ppm equals 1000 ppb.Units, so numbers mean the same to everyone.Beginner3 min
5. Dry basis vs wet basis in gas measurementA wet-basis reading counts water vapour as part of the gas; a dry-basis reading removes it.A hidden assumption in every reading.Intermediate3 min
6. Accuracy, precision, repeatability and drift in gas analysersAccuracy is how close a reading is to the true value; precision or repeatability is how closely repeated readings agree; drift is how the reading moves over time.What the specification promises.Intermediate3 min
7. Response time, T90 and sample lag in gas analysisT90 is the time an analyser takes to reach 90 % of a step change in concentration.Why a reading is late.Intermediate3 min
8. Gas analysis technologies compared: which sensor for which gasEach gas analysis technology works only on gases with the right physical property: electrochemical and paramagnetic sensors for oxygen, zirconia for hot oxygen, NDIR for gases that absorb infrared (CO, CO2, methane), thermal conductivity for binary mixtures such as hydrogen in nitrogen, ceramic or chilled-mirror sensors for moisture.A map of the sensor world.Beginner3 min
9. How to design a gas sample handling systemA good sample handling system delivers a representative, clean, dry sample at constant pressure and flow.Why the sample matters as much as the sensor.Intermediate4 min
10. How gas analyser calibration works: zero and spanCalibration compares the analyser's reading with a gas of known concentration and adjusts it to match.How a reading is kept true.Beginner4 min

Stuck on a real problem while you learn? Ask an engineer. Every lesson is checked against the figures in our catalogues.