| The Breakroom > The Water Cooler |
| Boiler Explosion |
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| DaveH:
GWRdriver, I think, also Ron wants to know if the boiler is tilted say from the horizontal with a low water level, then tilted back it likely to cause a major problem. DaveH |
| GWRdriver:
Thanks Dave. What will happen will depend upon several variables, among them he amount of water in the boiler, the depth and intensity of the fire, the state of the boiler (heat and pressure reading) before uncovering the crown, the number and size of safety valves, the length of time the crown is uncovered, and then of course the physical condition and design strength of the boiler. Lets say there is a good fire, the kind normally wanted for continuous running hauling passengers, the boiler is at full operating temperature and pressure and water is low but not in the danger zone if in a level position. What is most likely to occur if the crown sheet is uncovered and then quickly recovered is a momentary severe over-pressure which should be released by the safeties. If the crown is left exposed for longer and is allowed to get very hot the safeties probably can't release enough pressure soon enough and the probability is a failure will occur at the weakest point in the area closest to the pressure source. In the event of such a low water disaster-in-waiting the thing to do is stop the locomotive wherever it is, drop the fire immediately, and walk away (ie, wait) and allow the engine to cool. At that point whatever damage there will be has been done and under no circumstances should an attempt be made to introduce cold water into a hot boiler, even a tiny amount. This will produce an extreme over-pressure failure and a ruined boiler. Of the books listed above my favorite is the KN Harris book, but what I know about model boilers and boiler building (by far not everyhting there is to know) has been learned from several sources including books, magazines, my mentors, trial and error, and just building them. The photo is of a boiler for a 4.75" gauge (1"scale) tank loco I built for a fellow in Ohio a few years ago. |
| DaveH:
GWRdriver, I have the K N Harris book and the two by Turbal Cain. So I have no excuses :) :) :) :beer: DaveH |
| Ronkh:
Thank you DaveH, GWDriver, PTsideshow and all very much indeed for your replies. There is sooooo much to learn regarding steam. I have quite a few of the books mentioned, and I think it will be a fair while before attempting to make one once I've read and re-read them, plus taking in what has been posted on this site. Kind regards, Ron. |
| NickG:
I perhaps should have put a few more words around the video I posted. I agree completely with what GWRdriver is saying but I posted it to get across a point. In the UK small model boilers under 1.5 bar-litres (I think, but will check so correct me if I'm wrong), do not need testing or inspecting or anything. So the video is a good example of what can happen, any tom dick or harry could make or buy such a boiler and put it on show infront of thousands of people. It doesn't necessarily have to be an idiot either. When I was about 9 or 10 my grandfather gave me the Mersey model steam engine he bought as a kid, but the boiler had a leak so he soft soldered one end up using a soldering iron heated up in the coal fire, this did the trick and it worked a treat. I was thinking the other day it'll soon be getting to the time where I pass the model on to my children, but then I had 2nd thought - it's made from brass, soft soldered (neither of which are considered good practice now), doesn't have any stays, who knows whether the safety valve works, never been tested etc etc the list goes on. Imagine if I gave it to my children and something happened similar to that video - unlikely I know, but unlikely isn't good enough for me - I think it'll have a new boiler before my sons go anywhere near it. My grandad wasn't an idiot, he was a skilled engineer but maybe just wasn't aware of what could happen? There are other certain parameters that are designed in with such commercial boilers for instance, the meths runs out before it can boil away all of the water but these things can be by passed in the wrong or naive hands. So I posted that video just to try to make people aware of what could happen. With anything over 1.5 bar litres the boilers are subject to all the regulations and inspections etc so I agree such an incident is so unlikely if you did a risk assessment like we do at work, the risk would be very low due to the probability being so low. The consequences remain high though. Anyway, thanks GWRdriver for the information. It has been useful discussion for a few people I think. |
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