Posted By martin knox Where Calcium Hypochlorite crystals are used in the dosing pool plant system, apart from someone inadvertantly mixing a acid by mistake or purposely, what are the real risks of any chlorine gas be generated in sufficient quantities to require a chlorine detector to be fitted with alarm. I have queried this with the pool plant installers, and their line is " Calcium Hypochlorite has been used for a number of years instead of Chlorine Gas, and we have not come across one incident where chlorine gas or chlorine levels have been generated in quatities that would justify installing a detector on a installation. The installation at question is a new build 2002. Can anyone advise me otherwise or give hard evidence that I may put forward to argue the point under CDM or is there no real chance other than operator error or sabotage of this scenario being realised. I know all the usual stuff - Chlorine heavier than air etc, normally measured at 10 ppm etc, what I need is hard tangible evidence or facts to justify the need to install this technology. NB - all of the pool plant operators x 3, have been trained on PPOC, so they are trained. Thanks in advance Martin