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Environmental monitoring

Gas stack emission simulator

Low uncertainty in instrument testing, calibration and operator proficiency 

NPL have developed a facility to create controlled concentrations of gases within a circulating stream aimed at replicating the emissions typical of stacks. Coupled with traceable primary reference gases, this system can simulate gas emissions with low uncertainties ideal for instrument testing, calibration, as well as enabling proficiency testing of operators in making accurate measurements of stack emissions. 

The facility pumps either air or nitrogen as the main gas along with a selection of pollutant gases around the system to create a homogeneous mixture at a defined concentration which flows across the instrument sensors or sampling devices at speeds of up to 12 m/s.  The temperature of the system can be varied from ambient up to 180 °C with water vapour concentrations between 2% - 25%. The facility has two 5-inch ports at one end of the path length and two ports at the other end to allow instrument/sampling insertion.  




System summary 

Controllable operating temperature 

Up to 180 °C 

Vertical gas velocity 

Up to 12 m/s 

Sampling ports 

Sampling planes 

Maximum transverse distance 

1.5 metres 

Oxygen concentration 

0 – 25% 

Water vapour concentration 

2 – 25% 

Pollutant concentrations 


0 – 300 ppm 


0 – 300 ppm 


0 – 100 ppm 


0 – 50 ppm 


0 – 50 ppm 


0 – 50 ppm 


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