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Nitrogen trichloride in Dry Chlorine

The EZ-NCl3™ on-line analyzer system protects chlorine production units from dangerously high nitrogen trichloride concentrations that can potentially lead to explosion incidents. Considered as Best Available Technology (BAT) by several chlor-alkali associations, the analyzer system combines a process analyzer with a proprietary sample preconditioning system.


Manufacturing of chlorine by electrolysis of brine is common practice in the chlor-alkali industry. Side reactions with nitrogen impurities in the salt, however, may lead to the formation of nitrogen trichloride (NCl3) during the electrolysis process. Nitrogen compounds, mainly ammonia present in the brine are the main source for the formation of NCl3.  In certain parts of the chlorine production, the chlorine is either liquefied or evaporated. Due to its lower volatility NCl3 tends to accumulate in liquid chlorine. Downstream measurement of nitrogen trichloride levels helps to protect your process before certain thresholds are exceeded.

Best Available Technology: reliable and accurate analysis method described by Eurochlor and the Chlorine Institute (Pamphlet 21)

Field proven analytical technology

Avoids liquid chlorine degassing risks in laboratory

No need for laboratory staff to sample chlorine in the field using concentrated hydrogen chloride

Typical measuring ranges
0 – 1 ppm / 0 – 10 ppm / 0 – 100 ppm / 0 – 1,000 ppm / 0 – 2,000 ppm / 0 – 5,000 ppm NCl3

Analysis method    
Colorimetric measurement of NH4+ after absorbing of NCl3 in acid absorber

Detection limit    

Cycle time    
10 minutes (analysis)

Response time    
Higher ranges: 2 hours (incl. absorption of Cl2 gas)
Lower ranges: 4 hours (incl. absorption of Cl2 gas)

Product type: Process analyzers

Measuring technology: Colorimetry

Type of application process: Chlorine drying compression

Industries: Chlor-alkali