Re: Re: Boilers, Burners etc.
Hi all. I must take issue with a couple of Rays points. The fact that pumping water into an overheated dry boiler is a bad idea is of course correct. If the firebox crown plates are red hot then hitting them with cold water will cause local contraction and stressing, and although it may cause problems later it is unlikely to cause a huge rise in pressure, even if the boiler is in fact dry at the time. A working dry boiler probably does not have much pressure - no water - no steam, unless it has been left standing under fire but no steam draw. Under these conditions of low water and normal steam pressure it is probably either blowing off or near to it, and adding water will generate some extra steam pressure, but much less than you might expect. Consider the physics of the thing.The specific heat of copper or steel is far lower than that of water (Copper = approximately 0.09) so even if the plates are red hot the contained stored heat in them is not sufficient to evaporate much water and raise it to dangerous pressures - the figure of 1400 x volume water to steam is probably correct but quoted at standard or atmospheric pressure, it will be far less as pressure rises (Gas Laws). The formula is something like Heat Energy in plates = temp x Specific Heat of metal x Mass of metal. To raise water temp this must = Specific Heat of Water x temp rise of water x mass of water. But to boil the water to steam will take a further 540 cals per gramme of water. That means that the amount of water actually converted to steam will be quite small, and the pressure rise will be fairly small, since the mass of metal is much less than the water, and the specific heat of the metal is less than 0.1 of that of the water. Where the failur hazard comes from is the reduced strength of the plates at high temperature, allowing them to be forced down by steam pressure, often at a pressure below the normal working pressure of the boiler. At least one commercial Gauge 1 boiler will fail this way if operated at low water level with the gas burner full on and the water level too low so the crown is exposed. It usually fails unspectatularly by collapsing so a cross tube leaks and the burner gets extinguished. Note the crown is forced down by the steam pressure not vice versa. The issue of fusible plugs is not simple either. They do bring their own problems - At least one fireman has been killed in recent years when a fusible plug failed on a full sized loco, when the plug blew when a loco boiler was operating correctly with adequate water over the crown sheet. I know of another case a few weeks ago in full size, where the plug failed with about 20 psi on the gauge and also with adequate water over the crown sheet while steam was being raised. In 7.25 gauge on a very large narrow gauge ride in loco, a similar failure at full pressure dumped most of the contents of the firebox into the drivers lap. This one was not actually a fusible plug, but a firebox coil which perforated with a hole about the size a fusible plug would have opened. Jim Gregg. At 03:04 PM 10/6/03 -0400, you wrote: I've been following this thread, and I'd like to put my two cents in. I've worked with full sized stationary steam engines, and thought I do not have my operator's license as yet, I'm planning to take the test some time in the not too distant future. First the fusible plugs primary job is not to extinguish the fire, but to notify the operator that a problem exist, and when it melts you'll know it. When the fusible plug melts, the first responsibility of the operator is to extinguish the fire. To understand the dangers, one must first understand the why they occur. Two things to know about water and steam. For every on pound of pressure in the system, the temperature required to create steam rises one degree Fahrenheit. At just forty psi the temperature of the water and steam is well over 250 degree, and at 100 psi, its over 312 degree. The second thing to know is that one cubic inch of water will produce over 1400 cubic inches of steam. With this in mind, when water hits a dry heated crown plate, and instantly turns to steam, the pressure in the boiler raises drastically, the crown plate which is already too hot, is usually the first failed component, forcing the steam downward, as the failure occurs, pressure in the boiler drops drastically, as the pressure drops, the temperature required to turn water to steam decreases, causing the water in the boiler to turn to steam, again 1 cubic inch of water, produces over 1400 cubic inches of steam, and the boiler is history, and no longer setting where it was, this is the primary cause of steam explosions. The biggest danger with a boiler is not the steam in it but the water within. For this reason the fusible plug needs to be sized for the boiler, so as to allow steam to escape but to fast as to greatly effect
Re: Re: Boilers, Burners etc.
I have modified the tube in my Ruby such that it does not spit out the stack anymore. I shortened and pinched the origional tube then filed a hole just below stack level. This way the spray goes in the smokebox and falls down onto the track but most of the steam still goes out the stack. What little goes down below just adds to the effect of the locomotive. ; ] Trot, the modifyable, fox... | /\_/\ TrotFox \ Always remember, | ( o o ) AKA Landon Solomon\ There is a | \_/ [EMAIL PROTECTED] \ third alternative. From: JR May [EMAIL PROTECTED] A few weeks ago at Pine Creek we had our Railroaders Weekend/Open House and I set up some track for Ruby to run on in front of our machine shop. Actually used the tender deck for our 1914 Porter which was an ideal height. _ Instant message during games with MSN Messenger 6.0. Download it now FREE! http://msnmessenger-download.com
Re: Re: Boilers, Burners etc.
I've been following this thread, and I'd like to put my two cents in. Ive worked with full sized stationary steam engines, and thought I do not have my operators license as yet, Im planning to take the test some time in the not too distant future. First the fusible plugs primary job is not to extinguish the fire, but to notify the operator that a problem exist, and when it melts youll know it. When the fusible plug melts, the first responsibility of the operator is to extinguish the fire. To understand the dangers, one must first understand the why they occur. Two things to know about water and steam. For every on pound of pressure in the system, the temperature required to create steam rises one degree Fahrenheit. At just forty psi the temperature of the water and steam is well over 250 degree, and at 100 psi, its over 312 degree. The second thing to know is that one cubic inch of water will produce over 1400 cubic inches of steam. With this in mind, when water hits a dry heated crown plate, and instantly turns to steam, the pressure in the boiler raises drastically, the crown plate which is already too hot, is usually the first failed component, forcing the steam downward, as the failure occurs, pressure in the boiler drops drastically, as the pressure drops, the temperature required to turn water to steam decreases, causing the water in the boiler to turn to steam, again 1 cubic inch of water, produces over 1400 cubic inches of steam, and the boiler is history, and no longer setting where it was, this is the primary cause of steam explosions. The biggest danger with a boiler is not the steam in it but the water within. For this reason the fusible plug needs to be sized for the boiler, so as to allow steam to escape but to fast as to greatly effect the pressure within. To me this is the reason not to use soft solder, once it starts to soften and gives a little the drop of pressure coupled with the resulting increase in the amount of steam can cause an explosion even at a lower pressure. For this reason I believe water level is a much more import than pressure, assuming a well working relief valve. Dont get me wrong, pressure is important, and I dont think Id want to run with a pressure gauge, but watching the sight gauge is much more import than watching the pressure gauge. Ray Baughman From: Harry Wade [EMAIL PROTECTED] Date: 2003/10/06 Mon PM 12:20:44 EDT To: Multiple recipients of sslivesteam [EMAIL PROTECTED] Subject: Re: Boilers, Burners etc. At 05:57 PM 10/5/03 -0400, you wrote: On the other hand, a well designed silver soldered boiler will build up a very high pressure (probably more than 10 times operating pressure). In order for a theory to hold water all conditions, components, and influences on a system must be considered in proper proportion. I agree the above scenario could happen, in fact possibly as much as 14 x WP, if there was a constant and unlimited source of heat, but what's being ignored is that this condition could not occur with a burner the size of a fat pencil. There are simply not enough BTUs available to the system. If I were to apply a 1 oxy/acetylene rose tip (150,000+BTU/min) to a Ga1 boiler boiler of course I should expect trouble, but in actual typical operation that's not going to occur. The reason for building silver soldered boilers the way they have been, and should continue to be, is so that even a worst case scenario, where the boiler is dry and the burner is still on, a rather large margin of safety remains. I fail to see what some people in the Ga1 live steam hobby find so difficult and/or objectionable about that. When this eventually leads to failure, the steam/water escapes much more violently with parts being torn off and hurling through the air. Unsubstantiated rhetoric like this can do a great deal of harm if read and repeated by or to the wrong person. Rather than to conjur up disasters based upon incomplete and unrealistic physical scenarios, or constructing far-fetched justifications for doing it on the quick and cheap or indictments of doing it properly, I think the hobby would be much better served if that same energy were used to learn and promote good boiler building pratices. I continue to be amazed how many people still fail to undersand that there is a direct connection between certain time-proven boiler building practices and safety, meaning that if good practices are used there is no further need for discussions or conjecture about what might happen in the event of a boil-dry. We would, and do, know what would happen. As for the actual dangers, historically then overwhelming majority of steam and boiler-related injuries are from scalds and burns and it's no different for us. The ultimate solution could be a well designed copper boiler with one or two soft soldered melting plugs as last chance safety valves. These are
Re: Re: Boilers, Burners etc.
A few weeks ago at Pine Creek we had our Railroaders Weekend/Open House and I set up some track for Ruby to run on in front of our machine shop. Actually used the tender deck for our 1914 Porter which was an ideal height. I was not so much concerned about boiler safety as I was about Ruby spitting hot water out the stack. We carried 2000 passengers that weekend and I'd guess half took the shop tour with many taking the time to check out Ruby pulling a seven car mixed train (with power to spare!). Lots and lots of kids. Before starting Ruby up, I'd have to clear the kids back a few feet to keep the hot water and oil spray off of them. At Diamond Head and other public runs, is there a concern about the hot water tossed from the stack getting on kids? In other words, its not so much a boiler failure (very rare) that is a concern to me but rather the normal water tossing nature of a steamer when its cold and first moving out (very common). Seems like the operator has to be very aware of who is near him/her before starting out. BTW, if anyone is interested I can email a picture of Ruby running that weekend. Off hand I forget how many laps it ran, but it was two solid days, 11Am to 5PM with time off only for fuel and water. The train was three LGB log cars (very nice cars too), two LGB 4 wheel flats with load, Bachman Ely-Thomas caboose, an 8 wheel coach of unknown make, and a LGB 8 wheel caboose. Interestingly, the LGB caboose had coupler problems and was not used much. The log cars were jewels and I would recommend them highly. The true link and pin works nicely and the long link I used between the first car and the engine gave me plenty of room for my big hands to reach in quickly and control the throttle on the fly. Seemed like the heavier the load the better the control was of the locomotive.It was a very short track and speed was critical. Oh well, enough rambling. I'll have a pressure gauge for next year for sure! And a bigger track. J.R. www.njmt.org - Original Message - From: [EMAIL PROTECTED] To: Multiple recipients of sslivesteam [EMAIL PROTECTED] Sent: Monday, October 06, 2003 3:04 PM Subject: Re: Re: Boilers, Burners etc. I've been following this thread, and I'd like to put my two cents in. I've worked with full sized stationary steam engines, and thought I do not have my operator's license as yet, I'm planning to take the test some time in the not too distant future. First the fusible plugs primary job is not to extinguish the fire, but to notify the operator that a problem exist, and when it melts you'll know it. When the fusible plug melts, the first responsibility of the operator is to extinguish the fire. To understand the dangers, one must first understand the why they occur. Two things to know about water and steam. For every on pound of pressure in the system, the temperature required to create steam rises one degree Fahrenheit. At just forty psi the temperature of the water and steam is well over 250 degree, and at 100 psi, its over 312 degree. The second thing to know is that one cubic inch of water will produce over 1400 cubic inches of steam. With this in mind, when water hits a dry heated crown plate, and instantly turns to steam, the pressure in the boiler raises drastically, the crown plate which is already too hot, is usually the first failed component, forcing the steam downward, as the failure occurs, pressure in the boiler drops drastically, as the pressure drops, the temperature required to turn water to steam decreases, causing the water in the boiler to turn to steam, again 1 cubic inch of water, produces over 1400 cubic inches of steam, and the boiler is history, and no longer setting where it was, this is the primary cause of steam explosions. The biggest danger with a boiler is not the steam in it but the water within. For this reason the fusible plug needs to be sized for the boiler, so as to allow steam to escape but to fast as to greatly effect the pressure within. To me this is the reason not to use soft solder, once it starts to soften and gives a little the drop of pressure coupled with the resulting increase in the amount of steam can cause an explosion even at a lower pressure. For this reason I believe water level is a much more import than pressure, assuming a well working relief valve. Don't get me wrong, pressure is important, and I don't think I'd want to run with a pressure gauge, but watching the sight gauge is much more import than watching the pressure gauge. Ray Baughman From: Harry Wade [EMAIL PROTECTED] Date: 2003/10/06 Mon PM 12:20:44 EDT To: Multiple recipients of sslivesteam [EMAIL PROTECTED] Subject: Re: Boilers, Burners etc. At 05:57 PM 10/5/03 -0400, you wrote: On the other hand, a well designed silver soldered boiler will build up a very high pressure (probably more than 10 times operating pressure). In order for a theory to hold water all conditions, components
Re: Re: Boilers, Burners etc.
At 03:04 PM 10/6/03 -0400, you wrote: First the fusible plugs primary job is not to extinguish the fire, but to notify the operator that a problem exist Ray I agree when the boiler in question is full size, in which case the free area of a fusible plug is a tiny fraction of the area of the grate, however in typical large scale model practice the free area of a minumum sized effective fusible plug is relatively large compared to the grate area. In the event of a low-water emergency the net effect of a release is to extinguish the fire and rightly or wrongly those who use fusible plugs in model boilers rely on it to do that. Yes additional action, like dumping a coal fire, will probably be taken but all this happens in an instant and not all model locos have the ability to completely dump the fire on short notice so in model practice the fusible plug, when present, is thought of as a fire extinguisher rather than a warning device. Those without fusible plugs, and that would be the overwhelming majority of model boilers, and those with fusible plugs who want to run without an extended shut-down, rely upon a well maintained water gauge and feedwater pump or injector and paying attention to business to avoid trouble. There is a wide difference of opinion (in the U.S. anyway) amongst live steamers as to the benefits of fusible plugs in model boilers vs. their drawbacks. Some wouldn't be without them, some won't be bothered them. Neither camp can lay claim to be the lesser group of idiots so the friendly exchange of opposing ideology continues without a definite resolution. Personally I haven't used fusible plugs in a large scale boiler because those who I learned from didn't use them and/or it wasn't requested that I do so but that doesn't prevent me from seeing they do have their benefits. However I think the case for fusible plugs gets much stronger as scale, and boilers, gets larger and they are impractical in typical Ga1 boilers. Regards, Harry
RE: Re: Boilers, Burners etc.
Most users install a exhaust diverter in the snoke stack. It is nothing more than a larger tube with the end pinched off and holes drilled about 1/2 down from the top. It has also been called a chuff tube. Keeps the loco cleaner and stops the spitting. Steve -Original Message- From: JR May [SMTP:[EMAIL PROTECTED] Sent: Monday, October 06, 2003 10:49 AM To: Multiple recipients of sslivesteam Subject: Re: Re: Boilers, Burners etc. A few weeks ago at Pine Creek we had our Railroaders Weekend/Open House and I set up some track for Ruby to run on in front of our machine shop. Actually used the tender deck for our 1914 Porter which was an ideal height. I was not so much concerned about boiler safety as I was about Ruby spitting hot water out the stack. We carried 2000 passengers that weekend and I'd guess half took the shop tour with many taking the time to check out Ruby pulling a seven car mixed train (with power to spare!). Lots and lots of kids. Before starting Ruby up, I'd have to clear the kids back a few feet to keep the hot water and oil spray off of them. At Diamond Head and other public runs, is there a concern about the hot water tossed from the stack getting on kids? In other words, its not so much a boiler failure (very rare) that is a concern to me but rather the normal water tossing nature of a steamer when its cold and first moving out (very common). Seems like the operator has to be very aware of who is near him/her before starting out. BTW, if anyone is interested I can email a picture of Ruby running that weekend. Off hand I forget how many laps it ran, but it was two solid days, 11Am to 5PM with time off only for fuel and water. The train was three LGB log cars (very nice cars too), two LGB 4 wheel flats with load, Bachman Ely-Thomas caboose, an 8 wheel coach of unknown make, and a LGB 8 wheel caboose. Interestingly, the LGB caboose had coupler problems and was not used much. The log cars were jewels and I would recommend them highly. The true link and pin works nicely and the long link I used between the first car and the engine gave me plenty of room for my big hands to reach in quickly and control the throttle on the fly. Seemed like the heavier the load the better the control was of the locomotive.It was a very short track and speed was critical. Oh well, enough rambling. I'll have a pressure gauge for next year for sure! And a bigger track. J.R. www.njmt.org - Original Message - From: [EMAIL PROTECTED] To: Multiple recipients of sslivesteam [EMAIL PROTECTED] Sent: Monday, October 06, 2003 3:04 PM Subject: Re: Re: Boilers, Burners etc. I've been following this thread, and I'd like to put my two cents in. I've worked with full sized stationary steam engines, and thought I do not have my operator's license as yet, I'm planning to take the test some time in the not too distant future. First the fusible plugs primary job is not to extinguish the fire, but to notify the operator that a problem exist, and when it melts you'll know it. When the fusible plug melts, the first responsibility of the operator is to extinguish the fire. To understand the dangers, one must first understand the why they occur. Two things to know about water and steam. For every on pound of pressure in the system, the temperature required to create steam rises one degree Fahrenheit. At just forty psi the temperature of the water and steam is well over 250 degree, and at 100 psi, its over 312 degree. The second thing to know is that one cubic inch of water will produce over 1400 cubic inches of steam. With this in mind, when water hits a dry heated crown plate, and instantly turns to steam, the pressure in the boiler raises drastically, the crown plate which is already too hot, is usually the first failed component, forcing the steam downward, as the failure occurs, pressure in the boiler drops drastically, as the pressure drops, the temperature required to turn water to steam decreases, causing the water in the boiler to turn to steam, again 1 cubic inch of water, produces over 1400 cubic inches of steam, and the boiler is history, and no longer setting where it was, this is the primary cause of steam explosions. The biggest danger with a boiler is not the steam in it but the water within. For this reason the fusible plug needs to be sized for the boiler, so as to allow steam to escape but to fast as to greatly effect the pressure within. To me this is the reason not to use soft solder, once it starts to soften and gives a little the drop of pressure coupled with the resulting increase in the amount of steam can cause an explosion even at a lower pressure. For this reason I believe water level is a much more import than pressure, assuming a well working relief valve. Don't get me wrong, pressure is important, and I don't think I'd want to run
RE: Re: Boilers, Burners etc.
That's a great point, Steve, Thanks for bringing it up. It saves a lot of hot water and oil in the eye (and oil and crud on the Missuss's dress!) when firing most butane locos. However, it can't be done where a blower or exhaust nozzzle is required such as a coal or alky fired loco. Interestingly, with my two Merlin locos, (1985 and 1989) the exhaust tubes came as you suggested except that the tubes were slotted rather than drilled. I can't understand why all small loco builders don't do this. If done with imagination it can also produce a chuff sound. Every Ruby owner should do this. I like your mistype snoke box--that's at excellent term for our small locos! Geoff. Most users install a exhaust diverter in the snoke stack. It is nothing more than a larger tube with the end pinched off and holes drilled about 1/2 down from the top. It has also been called a chuff tube. Keeps the loco cleaner and stops the spitting. Steve
Re: Re: Boilers, Burners etc.
Diverters come in several forms. The Berkley Cricket came supplied with a curved, small brass tube, flared just enough to fit over the blower (exhaust) tube. I made some larger ones from flexible BX? cable covers, curved to direct the oil and water to the side of the loco. Made a couple with different tapers to fit the differing smoke stack diameters. Don't use when raising steam, only slip on when first valve movement clears the valves and cylinders. Remove then and put in pocket to achieve dirty look of engineer. - Original Message - From: Geoff Spenceley [EMAIL PROTECTED] To: Multiple recipients of sslivesteam [EMAIL PROTECTED] Sent: Monday, October 06, 2003 7:50 PM Subject: RE: Re: Boilers, Burners etc. That's a great point, Steve, Thanks for bringing it up. It saves a lot of hot water and oil in the eye (and oil and crud on the Missuss's dress!) when firing most butane locos. However, it can't be done where a blower or exhaust nozzzle is required such as a coal or alky fired loco. Interestingly, with my two Merlin locos, (1985 and 1989) the exhaust tubes came as you suggested except that the tubes were slotted rather than drilled. I can't understand why all small loco builders don't do this. If done with imagination it can also produce a chuff sound. Every Ruby owner should do this. I like your mistype snoke box--that's at excellent term for our small locos! Geoff. Most users install a exhaust diverter in the snoke stack. It is nothing more than a larger tube with the end pinched off and holes drilled about 1/2 down from the top. It has also been called a chuff tube. Keeps the loco cleaner and stops the spitting. Steve
