one little tap? to break tempered glass?? I guess you've never actually tried that. to each their own i guess because if you hit untempered glass as hard as you did to break the tempered glass you'd have lots of big razor sharp shards coming at you. most if not all your tanks bottoms are tempered and they don't spontaneously break.
7x3x3 ft Tempered vs 7x3x2.5 ft ordinary glass tank
- Thread starter Dre07
- Start date
I am reading this thread and the opposing views with interest. Thank you guys.
John, are you stating this having read the really helpful link by RD or having not? It addresses exactly the spontaneous breakage of tempered.
I read it. as always he comes with excellent sources. BUT.... my point is that if it was such a concern then why does every major manufacturer put tempered glass on the bottom of the tank? surely there'd be more failures of the spontaneous variety.
when I redid my 150g the bottom was 1/2" thick tempered glass and it took quite the forceful impact to break it out. I replaced it with 1/2" tempered. it is a marineland tank, the one I told you about.
___________
· Breakage due to nickel sulfide (NiS) inclusions
Nickel sulfide inclusions are small polycrystalline spheres with a metallic appearance generally ranging from 0.1 mm to 2 mm in diameter. Sulfur is present in the raw batch materials in the form of sodium sulfate. Traces of nickel could also be present in the other batch material or could come from machinery that contains nickel-bearing alloys (i.e. stainless steel).
If sulfur ions and nickel ions are present in the batch material, there is no certainty that nickel sulfide will form. However, if this type of inclusion goes through a phase transformation from an alpha to a beta phase under a specific combination of time and temperature, there could be a change in crystalline structure, accompanied by a volume expansion of slightly over 2%. Although this volume change is slight, if the inclusion is located in the central tensile region in tempered glass, it can cause the internal tension stress to be released. The result is spontaneous breakage of the tempered glass into small fragments.
In conclusion, the requirement for a nickel sulfide stone to cause spontaneous breakage of a tempered glass can then be summarized as follows:
¨ Nickel, derived from trace amounts in the sand, firebrick or machinery must be present.
¨ Sulfur must be present.
¨ A rare crystalline from of nickel sulfide must occur.
¨ The rare crystalline form must end up in the center of the ribbon thickness as the ribbon of glass leaves the tin bath.
¨ That part of the glass ribbon in which that rare stone occurs must be made into a tempered glass.
¨ When the rare form of nickel sulfide undergoes transformation, it must develop sufficient additional tensile stress so as to exceed the tensile strength of the glass at the break point.
As mentioned above, all of these must occur, not just one, or two or three of them. Thus, the actual occurrence of a break caused by a nickel sulfide stone is an extremely unusual event, not an ordinary one.
so this is my main take away …. " the actual occurrence of a break caused by a nickel sulfide stone is an extremely unusual event, not an ordinary one."
when I redid my 150g the bottom was 1/2" thick tempered glass and it took quite the forceful impact to break it out. I replaced it with 1/2" tempered. it is a marineland tank, the one I told you about.
___________
· Breakage due to nickel sulfide (NiS) inclusions
Nickel sulfide inclusions are small polycrystalline spheres with a metallic appearance generally ranging from 0.1 mm to 2 mm in diameter. Sulfur is present in the raw batch materials in the form of sodium sulfate. Traces of nickel could also be present in the other batch material or could come from machinery that contains nickel-bearing alloys (i.e. stainless steel).
If sulfur ions and nickel ions are present in the batch material, there is no certainty that nickel sulfide will form. However, if this type of inclusion goes through a phase transformation from an alpha to a beta phase under a specific combination of time and temperature, there could be a change in crystalline structure, accompanied by a volume expansion of slightly over 2%. Although this volume change is slight, if the inclusion is located in the central tensile region in tempered glass, it can cause the internal tension stress to be released. The result is spontaneous breakage of the tempered glass into small fragments.
In conclusion, the requirement for a nickel sulfide stone to cause spontaneous breakage of a tempered glass can then be summarized as follows:
¨ Nickel, derived from trace amounts in the sand, firebrick or machinery must be present.
¨ Sulfur must be present.
¨ A rare crystalline from of nickel sulfide must occur.
¨ The rare crystalline form must end up in the center of the ribbon thickness as the ribbon of glass leaves the tin bath.
¨ That part of the glass ribbon in which that rare stone occurs must be made into a tempered glass.
¨ When the rare form of nickel sulfide undergoes transformation, it must develop sufficient additional tensile stress so as to exceed the tensile strength of the glass at the break point.
As mentioned above, all of these must occur, not just one, or two or three of them. Thus, the actual occurrence of a break caused by a nickel sulfide stone is an extremely unusual event, not an ordinary one.
so this is my main take away …. " the actual occurrence of a break caused by a nickel sulfide stone is an extremely unusual event, not an ordinary one."
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Yes, exactly, why is that do you think? If for safety purposes, then why not the entire tank? Why just the bottom?
1. Because the bottom pane of glass is the most likely to get broken.
2. Because it's too costly to use on the front/back/both sides, AND the bottom
3. Because tempered glass can fail from sharp force, and from spontaneous breakage, where annealed typically does not.
BIG companies = BIG CYA legal departments
This isn't a one off boys & girls.
Reports Of Spontaneous Glass Breakage On The Rise
Glass tables and shower doors are very popular. But there are a number of reports of them shattering without warning.
newyork.cbslocal.com
Video Consumer Alert: Spontaneously Shattering Glass
Why do some Tables, shower doors and other large panels of glass have the potential to suddenly shatter into a million pieces for seemingly no reason?
There's plenty more where that came from.
well
RD.
I agree with your points as you listed. as far as those glass tables and shower doors go theres other forces at work that aren't present in a tank. like being twisted or under edge pressure from frames etc also they're manufactured cheaply so quality control is an issue. I get my glass from a local supplier that only uses 100% made in America glass manufacturer and its at a premium price. I still think that the force needed to break tempered would break any glass even annealed.
RD.
I agree with your points as you listed. as far as those glass tables and shower doors go theres other forces at work that aren't present in a tank. like being twisted or under edge pressure from frames etc also they're manufactured cheaply so quality control is an issue. I get my glass from a local supplier that only uses 100% made in America glass manufacturer and its at a premium price. I still think that the force needed to break tempered would break any glass even annealed.
The point is, tempered glass is not exempt from breaking, spontaneously as seen above, or from blunt force, as seen in this video.
IMHO the only thing that tempered adds with regards to safety, is that if/when it does break, it breaks in a more safe manner. Then again, how many stories has one read over the years where someone lost an arm, or leg, or even a finger or toe, when an annealed tank broke? lol
IMHO the only thing that tempered adds with regards to safety, is that if/when it does break, it breaks in a more safe manner. Then again, how many stories has one read over the years where someone lost an arm, or leg, or even a finger or toe, when an annealed tank broke? lol
Correct - so then what's the point? I thought that it was all about safety, so when the glass breaks, no one gets hurt? That is clearly why many manufacturers use tempered glass - in the bottom pane. CYA legal reasons.
Yet at least in some cases, it does not. Watch the videos a few more times. lol
This is not something new, spontaneous breaking of tempered glass has been known about within the glass industry for decades. It is a very real problem, especially in commercial applications where consumers can get hurt. The fact that you never even heard about it until I posted it here just proves how little many people know about this phenomenon. Yes, it's a rare event, but certainly not so rare that one should rule it out.
Another common spontaneous tempered glass issue, found within ovens, this one being a Kenmore.
123 complaints in one year. (USA) Rare, but still, too frequent for my comfort level.
maybe we should stop the use of glass and just go with acrylic?
I think that it all boils down to the application, the overall cost, and ones personal comfort level. My point in posting here was simply to demonstrate that "safety" glass isn't always as safe as what it's cracked up to be. No pun intended.
