Air Cooled Hood Glass Explosion! Reasons?

[Sinner D]

Hello fellow farmers! This morning when my flowering room got started, I was surprised to find that one of the four air cooled fixtures that I run apparently had the glass shatter in place and rain down on my unsuspecting White Rhino's. All's well with the ladies, nothing too damaging, but I'm still left wondering how?!
I cool all my fixtures in a loop that emits all the hot air to the outdoors. All the fans stop runnin' when the lights go out in the evening. Nearest I figure, the change in the seasons allowed some cool air down the duct and too quickly cooled the glass causing it to shatter. But there are two other fixtures closest to the out-take that would have had a similar, if not more immediate, reaction in this scenario. My intake fan is however right above the damaged fixture, and even though I shut it down promptly with the rest of the fans in the room, I feel it still may have been a factor. Has this ever happened to anyone else?? I mean, I've seen people selling their used air cooled hoods w/o glass on CL before, but I always imagined it was just by accident the glass was broken. Never thought it could just shatter in place for seemingly no reason...o_O

 

[seaslug]

Maybe there was an existing flaw/micro crack in the glass that broke. Like a windshield with a ding, a change in temperature can crack the whole thing. Just a guess.

 

[Sinner D]

i use outdoor air to cool mine and in winter that can be some very cold air,like 10f or lower and the only thing i have seen is some water condensating on the inside of the glass but i never had one break.are you sure someone didnt go in the room and bang their head on that hood? or maybe the glass was already weak and the vibrations from your fan overhead did it?thats the first i have ever heard of one just popping on its own.

You know, I've had some condensation on the inside of one of the four lights in the chain in the past. Although it was a different fixture, it was neighboring. After more careful thought, I do have a slight recollection that the piece of glass that broke, may have had a chipped corner. So, you could be right on in assuming that a weak spot in the glass along with the inline fan vibrations, climate change, may have been what did it.