Posted By Charley Farley-Trelawney
Paul

As the effect of NSi is very small, (only 1 critical inclusion occurs in every 13 tonnes of glass that they produce, and that 90% of the inclusions will cause premature breakage during their heat soaking process. This means that only one nickel sulfide inclusion will ‘get through’ for each 12,700 m2 of 4 mm heat soaked toughened glass, or for each 8,470 m2 of 6 mm heat soaked toughened glass)and unless you are fully trained in the subject it is not quite so easy to spot, could you have a report produced by the original installers to satisfy you that all is as it should be before taking further action and is the glass causing you concern mounted overhead? If it is the latter then I have included a link that you will find of great benefit.

http://www.ehj-online.co...2000/july2002/july1.html

I think in the first instance I would be inclined to bring in a specialist. I once arranged for a very well knows chain of stores to include a retrospective film to be fitted to the main store front windows, which would prevent the spread of glass,(SFARP was all well and good but remote as it was the potential injury could be fatal, the cost was horrendous, but several did go over the years, mainly from a vandalistic prospective; they stayed in place, broke but remained in one piece; the biggest problem is overhead, netting is an option but very expensive and not great to look at, lower light levels but much safer.

Sorry can't be more help

Posted By Pete48
Paul, I cannot answer your technical question directly. As others have said you need a techie to do that for you.
By way of some lower level practical help I do know that the regulations allow the use of toughened glass overhead. The glass must be heat soaked if this a safety critical location.
When toughened glass breaks we all know that it breaks safely into small particles. However, when it is overhead the particles can fall as a "lump" forming a mass of glass that may cause impact injury (and maybe some very minor cuts.)
The codes suggest that to reduce the risk of injury the thickness and height above floor level is limited to reduce the risk of injury. For heights up to 5m above floor level toughened can be considered if the other glass products cannot be used. Between 5m and 13m above floor level restrict the toughened thickness to 6mm and 3m2 in one pane. Over 13m above floor level toughened is not recommended. Some form of laminated glass is usually specified here.
Recommend that you check out with the designers, installers or the glass supply company as to exactly what type of glass you have installed. The glass company would have supplied to the spec from the architect subject to meeting relevant codes.
Hope this helps to give you a benchmark as to the inherent risks in your installation.