Question

We've recently experienced excessive corrosion on stainless steel within indoor pool environments. We believe this is due to chloramine (gasses) in the atmosphere. To test this, I plan to create a small, closed environment (loosely sealed to contain gas but limit pressure buildup), in which I'll mix a solution to create some chloramines and hang material samples.

I assume (not from chemical background) that introducing pool chlorine (granular calcium hypochlorite 70%) and ammonia (as cloudy ammonia NH3 20g/L) to water, will kick most of this off. Attempts to maximise chloramines (Fig.1) will hopefully be achieved by keeping chlorine levels below breakpoint (Red local minimum - Fig.2)

I am slightly concerned after reading some articles and forums stating nitrogen trichloride (trichloramine) can be explosive. This factsheet states its only formed 'after breakpoint'. Additionally, some say 'in sunlight, will decompose', whilst others show it exploding in sunlight

Can anyone provide advice on how to safety generate monochloramine and dichloramine gasses without generating dangerous amounts of nitrogen trichloride?

I have an (ancient) Palintest photometer to monitor free/total chlorine but does not display ammonia.

Answer 1

To generate monochloramine and dichloramine gases without generating dangerous amounts of nitrogen trichloride, it's important to carefully control the levels of chlorine and ammonia in the solution.

Step-by-step explanation:

To generate monochloramine and dichloramine gases without generating dangerous amounts of nitrogen trichloride, it's important to carefully control the levels of chlorine and ammonia in the solution.

Chloramines are formed when chlorine reacts with amines in organic substances such as ammonia. By keeping the chlorine levels below the breakpoint (where free chlorine is no longer present), the formation of nitrogen trichloride can be minimized.

This can be achieved by using a low concentration of pool chlorine (calcium hypochlorite) and ammonia in the solution.