Foundations

What this track covers

Everything else in gas analysis rests on a small set of ideas: how a concentration is stated, how pressure and temperature change what a sensor sees, and what words like accuracy, drift and T90 promise. This track builds those ideas in nine short lessons.

If you already work with analysers you can skim it. If you are new, read it in order; later tracks assume it.

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.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.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.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.Beginner3 min
5. ppm to mg/Nm3: volume vs mass concentrationMass concentration in mg per cubic metre equals ppm times molar mass divided by molar volume, and the molar volume depends on temperature and pressure.Intermediate3 min
6. 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.Intermediate3 min
7. 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.Intermediate3 min
8. Response time, T90 and sample lag in gas analysisT90 is the time an analyser takes to reach 90 % of a step change in concentration.Intermediate3 min
9. How to read a gas analyser datasheetRead a datasheet in four groups: what it measures (gas, range, minimum range), how well (accuracy, repeatability, drift, response), what it needs (sample conditions, power, utilities, ambient limits) and what it gives (outputs, approvals, options).Intermediate5 min

Next track: Measurement principles