The S4 QUASAR Heated vacuum chemiluminescence gas analysers combine high levels of performance with flexibility and ease-of-use in the continuous measurement of NOx, Nitric Oxide, Nitrogen Dioxide or Ammonia. Heated vacuum chemiluminescence is the reference method for monitoring NOx (combined NO and NO2), offering higher sensitivity with minimal quenching effects, and a heated reaction chamber facilitates the processing of hot, wet sample gases without condensation. The reaction of NO (Nitric Oxide) and O3 (ozone) to produce the chemiluminescence is greatly improved under vacuum, with a better signal-to-noise ratio, and a fast response time makes it ideal for real-time reporting applications. This method is specified in many standards, such as EN 14792 and Method 7E.