This is what I was concluding also. When the concave base “pops,” there’s enough pressure that it just basically keeps going.
You know what this means, of course: The MythBusters need to explore this “why does the bottom fail and the tank go up like a rocket?” question, and validate the analysis in this thread, by testing a variety of water heaters and other high-pressure vessels to see how the design of the tank influences the likely failure points. We get concrete data, and lots more things blowing up. Win-win.
I apologize for being unclear. The city provides cold water to my house, via a system of pipes that are pressurized by water towers. Some of this cold water is diverted to my water heater, which heats the water and returns it back into my house system, where it can be accessed by opening one of two valves (the one labeled “hot”) at various sinks, a washing machine, and a shower.
It doesn’t provide the water. It heats the water. Hence the name – water heater.
I think the weight of the water does add to the stress and when the whole container is near failure the added weight would make the bottom pass the fail point first, This is if the bottom and top have the same strength in construction.
You know, I now believe that your confusion is not my fault. Can you really have read my posts and wonder if my water heater actually heats water? I said it was around 120 degrees F, just upthread. I suppose you could argue that that isn’t hot, but it would seem to me to be quibbling.
It would be a hot water thermos if it didn’t heat the water, and it does heat the hot water that is starting to cool down, but is still hot. Technically it is a hot water heater.
Thing is that English as used isn’t logical. Or, it is but at a contorted level. We refer to the stuff that comes out of the tap with the red “H” on it as “hot water” not merely because it is water and it is hot, but because that is the usual term for domestic water that comes out of the tap with the red “H” on it.
The thing that produces said “hot water” is a water heater. So just as we call the thing that produces bread a bread maker, we call the thing that produces the hot water a hot water heater. Yes, there is redundancy, but there you go.
I watched the vid via provided link and paid attention to the footage during the comment “went from concave to convex”. There are remnants of weld visible with shell metal surrounding, not surprising with a mild steel at ~45k PSI and weld at 70k PSI.
The inverted bottom head is forced outward and rips the weld seam loose.Note the shell maintains cylindricity until return to tarmac.
Had they maintained a true hydrostatic test ( Let’s not fill it all the way!) it would have made for boring TV. The ullage allowed the formation of steam and corresponding enormous expansion.
My question amounts to: why is the bottom *consistently * the weakest point. And between **Matt ** pointing me in the right direction and my own research (see #13) the answer would seem to be: it is constructed completely differently, as it is concave while the top is convex.
What really held me up was that (as I mentioned above) I once pulled one apart and the top and bottom were constructed the same. So I couldn’t see any obvious reason why they would always blow out the bottom. But it seems, according to one cite I found, that at least in Australia the common design changed from “top and bottom both concave” to “top convex, bottom concave” in about 1981.
And the thing that produces sliced meat is a sliced meat slicer. The thing that sews button holes is a sewn button hole sewer. The thing that paints lines on the road is a painted line painter. Right?
The thing that produces hot water is a hot water producer perhaps, but not a hot water heater. My cite is your quote, above. As well as my link upthread to where they sell water heaters.
There’s a hill in the UK the name of which, if you translate it, means “hill hill hill” , each “hill” being in a different original language. Nonetheless, the name of the hill, is the name of the hill
“hot water heater” gets 1.7m hits on google including hits on manufacturer websites, wikipedia, howitworks etc.
It’s a recognised term. It may be illogical, but that’s English for you. Get over it.
The proper name, perhaps, but the thing named is simply a hill, as you point out yourself.
And “water heater” gets 2.44m hits.
Brilliantly played. I was a little foggy on where you were going with your pseudo Socratic musings, but now I see that it was all a clever trap. So clever you could put a tail on it and call it a weasel. My hat is off to you, sir!
