All my alcohol fired locos are self-regulating to some extent - it's the very nature of the a forced draft system - the less steam passes from the blast pipe into the smoke box, the less pressure drop you get in the smoke box which leads to less draft and vice versa. No steam in the smoke boxes means no draft which means no fire assuming the smoke box, fire tubes etc are properly sealed - it's why you have to use the blower to create draft when the loco is stationary. On all my alcohol locos (including an Aster Pannier) if you close the regulator and don't open the blower, the fire goes out or hunts for air. On a butane loco, the fire doesn't depend on vacuum in the smoke box, so running out of water is a seriously bad thing which is why most butane fired locos size their gas containers to be just less than the amount of gas which will cause a full boiler to go dry.
My 'alchies' all seem to run better when the water level is below the flues - I put it down to drier/hotter steam as the flues heat up without the cooling effect of water and act as unintended 'super-heaters'. Not good for the boiler, so not recommended but a good sign of needing more water. -----Original Message----- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Harry Wade Sent: Thursday, January 25, 2007 12:36 PM To: Small-scale live steam discussions Subject: Re: [SSLiveSteam] Aster JNR At 06:50 PM 1/25/07 +0000, you wrote: >After the water falls below the flues they are >forced to radiate their heat to the air (or >conduct their heat into surrounding metal >structures) so the water cools and pressure drops, >slowing the engine. But by this point the engine >is 'running dry' and may have suffered some damage. Perhaps, but as long as there is steam within the boiler you will not be running dry, or completely so. Remember, in a historical sense "running dry" meant that the crown sheet was uncovered, not that the boiler was empty of water or steam. Anyone who has tried to soft solder a joint in a copper plumbing line where water remains in the line can attest that the heat absorbing and conducting qualities of steam under certain conditions can carry heat away faster than it can be applied by a small flame or torch. Such is the case with our boilers. If, however, you run the boiler truly dry and don't douse the fire the result for us is generally fried O-rings, seals, gaskets, and paint. (You want fries with that?) I have a Pannier which exhibits visibly livelier behavior when the water level is very low. I have attributed this to drier/hotter steam, and the subsequent increase in expansion within the cylinders, the result of some superheating of the remaining steam taking place at the upper flues, which are by that time uncovered. This is not IMHO due to an increase in pressure for if that were the case the safety would lift constantly or at least more frequently, but it doesn't. I have never in my life seen and meths fired locomotive which was in any way self-regulating, or self-extinguishing, in the way described, nor would I want one. For many of us one of the pleasures of live steam is the challenge of driving the locomotive, learning its behavior, balancing the load, fuel, water, blower, throttle, and reverse to make it out and back. Regards, Harry Wade Nashville Tennessee _______________________________________________ SSLiveSteam mailing list Send messages: [email protected] Cancel subscription: http://postfix.45mm.com/mailman/listinfo/sslivesteam Rules: http://www.45mm.com/sslivesteam_guide.html _______________________________________________ SSLiveSteam mailing list Send messages: [email protected] Cancel subscription: http://postfix.45mm.com/mailman/listinfo/sslivesteam Rules: http://www.45mm.com/sslivesteam_guide.html
