Well...except for that whole "Best Friend of Charleston" thing...
What About Gettysburg Disaster in 1989?. That was a Boiler explosion and the crew got seriously hurt!
Well...except for that whole "Best Friend of Charleston" thing...
What About Gettysburg Disaster in 1989?. That was a Boiler explosion and the crew got seriously hurt!
Sorry, it was NOT an "explosion". That was a Canadian Pacific steam locomotive, so the firebox was designed & built with special staybolts that relieved/gave way under very high stresses and thus prevented a total catastrophic "explosion". Yes, cab crew members were pretty badly burned when the steam and burning fire coals released into the cab, but nobody was killer. The locomotive had been operating with low water, and upon topping their grade, the crown sheet staybolts partially gave way. Again, the safety valves did not prevent the failure.
OK, I have one very objective question. Is there a Low Water Cut-out safety device? I'm assuming the answer is "no". I won't argue for a second that low water leads to explosions.
OK, I have one very objective question. Is there a Low Water Cut-out safety device?
Not sure what you mean by "Low Water Cut-out safety device", but many railroads had the "low Water Alarm" system, that sound a VERY audible alarm whistle inside the cab, when boiler water level went below a predetermined level. However, the "Low Water Alarm" was just that, an Alarm only, and the crew could simply ignore the Alarm whistle and simply keep on going, if they were stupid enough.
Some railroads had "Drop Plugs" that were threaded into sockets welded into many place in the crown sheet. The "drop" portion of the plug was silver-soldered into its housing with a tall portion that stuck up into the boiler water. Thus the boiler water kept the solder from melting, but if the water level became too low, the protruding of each plug was exposed to very hot steam, which transferred the heat downward and melter the solder, thus releasing the whole physical plug and resulting boiler water/steam into the firebox and extinguishing the fire (either oil or coal).
I'm assuming the answer is "no". I won't argue for a second that low water leads to explosions.
But there is just no way three pops will keep the boiler from exploding during the instantaneous pressure spike that occurs when relatively cold water hits a red hot crown sheet.
That apparently doesn't happen. The Pennsy did an experiment where they sprayed cold water on a hot crown sheet, and nothing happened.
So the crown sheet didn't rupture in the PRR "rest"? What about all the other catastrophic boiler explosions as a result of low water and a bare crown sheet? Multiple safety valves sure didn't help, did they?
Hot, you're so gung-ho to prove a point that you're all over the map.
I never said safety valves would prevent a boiler explosion in a low-water situation. I said SAFETY VALVES WERE INVENTED AND USED FOR AT LEAST A CENTURY BECAUSE EARLY ENGINEERS BELIEVED BOILER EXPLOSIONS WERE CAUSED BY OVERPRESSURE.
You don't have to believe this, and somehow I doubt you will.
Please keep in mind that my experience relates to stationary boilers.
The low water safety initiates a Master Fuel Trip. It applies to Pulverized Coal, Fuel Oil, and Natural Gas fired boilers. In short, low water trips a fuel cut-out. Assuming you have a load on the boiler, the pressure will drop pretty fast. The cut-out point is pretty conservative to prevent equipment damage.
For a locomotive, I can see how this could really be a real PITA.
Please keep in mind that my experience relates to stationary boilers.
The low water safety initiates a Master Fuel Trip. It applies to Pulverized Coal, Fuel Oil, and Natural Gas fired boilers. In short, low water trips a fuel cut-out. Assuming you have a load on the boiler, the pressure will drop pretty fast. The cut-out point is pretty conservative to prevent equipment damage.
For a locomotive, I can see how this could really be a real PITA.
You are correct about that feature being a real PITA. Same reason, back in the old days, when an EMD diesel unit got a Hot Engine Alarm, nothing happened except the alarm bell and a "Hot Engine" alarm light. The thinking was, in those days, NOT to derate HP so as to keep the train moving, and let the operating crew handle it per their railroad's policies.
One comment to support your statement. Technically it is low pressure, not high pressure that blows up the locomotive in a tube sheet failure. As an FYI to the Forum, what we regard as a "Steam Engine" is a Fire Tube Boiler.
Compromising a tube sheet on a steam locomotive would result in a boiling liquid expanding vapor explosion (BLEVE). The boiling temperature is dependent upon pressure (high pressures will yield high boiling temperatures). If the tube sheet rupture is catastrophic, you are left with a large mass of water @ high temperature transitioning to a low pressure. This causes the entire volume of water to change state from liquid to gas (steam) virtually instantaneously. The resulting expansion is so rapid and violent that it is classified as an explosion.
Keep in mind that this change in state is occurring on the fire side. Obviously the water side of the boiler is designed to contain high pressures. The fire side is not.
rattler21 posted:
I don't know what went wrong, but something did. John in Lansing, ILL
Low, or no, water over the crown sheet. Virtually ever case investigated was found to be operator error.
Hot Water posted:rattler21 posted:
I don't know what went wrong, but something did. John in Lansing, ILL
Low, or no, water over the crown sheet. Virtually ever case investigated was found to be operator error.
Well, that was the case after at least 1912. Before that, however, mechanical engineers believed quite a bit differently--and "virtually every case investigated" yielded a completely different conclusion than your experience will allow.
"The cause of boiler explosions is excessive pressure, and the fact that such disasters are of not infrequent occurrence, whether arising from neglect or otherwise, points forcibly to the necessity of providing against them in every possible way...The first is in the use of a perfect automatic pop safety valve, absolutely certain in its action, prompt in opening and closing, and fully sufficient in capacity to relieve the boiler from any excessive pressure beyond the amount intended to be carried as a safe limit."
[Emphasis added]
--The Science of Railways, Locomotive Appliances, by Kirkman, 1912
We obviously know differently today.
All well and good, however the two locomotive failures pictured above were NOT related to prior to 1912 conditions, and were BOTH the result of low water crown sheet ruptures. If you want to discuss 19 th century engineering and practices, I will bow out. Neither of us have any actual "hands on" experience in that area anyway.
Hot Water posted:All well and good, however the two locomotive failures pictured above were NOT related to prior to 1912 conditions, and were BOTH the result of low water crown sheet ruptures.
Not sure they were crown sheet ruptures, but point taken.
If you want to discuss 19 th century engineering and practices, I will bow out. Neither of us have any actual "hands on" experience in that area anyway.
If "hands-on" experience with 19th century engineering and practices, and the way those who came before us viewed the world, was the prerequisite for discussing history, we would be in for a world of hurt--and ignorance. The historical record exists. You can either read it and learn from it, as I've chosen to do, or ignore it--at your loss.
I have preferred to learn from those before me, i.e. the Machinists, Boilermakers, Blacksmiths, Engineers and Fireman, to name just a few crafts, from the 1930s and 1940s. That is the age and design of the equipment I prefer to work on.
Who do you think they learned from?
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