"Notes from the Unit Shop"
Kevin O'Connor's advice for the beginning small scale live steamer
Getting Started with Frank S.
Part Three of a series on tapping the maximum potential of a Gauge 1 locomotive
"Efficient and Fun operation of a Gauge 1 locomotive"
The biggest difference between Gauge 1 live steamers and the rest of the operating garden railway fraternity is the need for “hands on” control of locomotive operation, with the attendant need to adjust speed, direction, boiler water levels, and fuel flow/addition as opposed to operations utilizing either battery or track power and/or radio control. This need to be “up close and personal” with the live steamer is what fascinates me and binds me to the hobby. I’m sure I’m not alone. This difference is also what discourages some garden railroaders from giving steam power a try.
The first issue is “What is the proper operating boiler steam pressure for my locomotive?” It depends on a couple or three things. Each boiler is designed for a particular working pressure and this pressure should not be exceeded. The Frank S. boiler steam pressure gauge indicates up to 5kg/cm (70 psig). There is a general rule of thumb in the full-scale engineering business that states that a pressure gauge should be able to indicate an internal pressure 2 times the working pressure of the vessel that it is monitoring.
From this general rule we can surmise that Frank S. is
designed around a maximum working pressure of 2-1/2 kg/cm (35 psig), but that is
not the most efficient boiler working pressure. The lowest operating pressure that will do the job is where
you want to be, because a boiler operating at a lower pressure will radiate less
heat per unit of time than will an identical boiler of a higher boiler pressure
and temperature. Boiler pressure
and temperature are directly related and heat radiated by a boiler does no
useful work and wastes fuel.
My personal preference is to operate between 1-1/2 to 2 kg/cm. A stock Frank S. safety valve will start to blow off at approximately 2 kg/cm (25 psig). This stock safety valve is really a pressure relief device and not a true safety, and so it is prone to weep steam and will not just blow off and reset itself. It is also not adjustable. If you want to operate with a proper safety valve you can obtain a safety valve from an Aster Americanized Mogul and replace the stock pressure valve.
As you ease your Frank S. onto the mainline you must pay close attention to the boiler operating pressure. If it drops or increases from the “ideal” pressure you must adjust the butane gas flow to the burner to maintain pressure within 10% of the ideal. Don’t do what most of the meths guys do and run with the safety popping, or weeping constantly. It may look colorful, but it is wasting fuel and water. They run that way because most do not understand the interplay between wick tightness, fuel hopper feed control, varying loads and grades, and they have no quick and easy way to adjust fuel flow to their burners. Most of them are just happy to be running at all, and if they haven’t lit off the track in doing so, so much the better.
As soon as boiler pressure is adjusted consistent with the load attention must be paid to boiler water levels. I do not let my water level fall below ½ glass before I top up to ¾. Having a Goodall valve in the boiler fill boss is mandatory for efficient operation.
There are three reasons not to let the boiler water level drop out of the glass.
Once it drops from sight you no longer know with certainty what the level is.
Once the hot gas flue tube starts to be uncovered by boiler water, the effective surface area available to generate steam pressure drops at an exponential rate and the chance of overheating the flue rears its ugly head. The last reason is that the more hot water that you have in the boiler as you top-up the less that the boiler pressure will drop as the result of adding water at ambient temperature.
The last fact, call thermal inertia, allows for fast pit
stops and timely, returns to operation. My
practice is to run at 2 kg/cm and then add water as needed till the boiler
pressure drops to 1-1/2 kg/cm. If
more is needed I just lap the track and repeat the drill until I’m up to
During the initial steamup and first few laps pay close
attention to the temperature of the water in the water bath surrounding the
liquid gas fuel tank. During the
steamup process we anticipated the cooling of the butane storage tank due to the
evaporation of liquid fuel into gas by filling the water bath with warm water,
but by now, depending on the locomotive’s load and the ambient temperature,
the water is most likely getting cool, if not cold.
The sound of the burner will signal this condition, but usually too late
to be on top of the situation.
Refreshing the water bath with warm water is a two-step
method involving the use of a 50cc animal syringe attached to a suitable length
of silicone tubing, and a pint Thermos bottle.
Stop the locomotive, remove the coal load if you have one, and using the
syringe draw the cold water out of the tender’s water bath.
Trickle warm water from the Thermos bottle into the bath.
Be careful not to pour too fast as a sudden increase in gas pressure can
extinguish the burner flame and you will have to relight when you are finished
topping off the bath.
If the fire should go out for any reason during operation,
it is imperative to make sure that the throttle valve is fully closed prior to
trying to relight the burner. If
your locomotive is equipped with R/C, just moving the motion control bar to
neutral will not cut it, as the reversing block will still leak a small amount
of steam through the piston valves. The
tiniest amount of steam vapor emanating up through the stack is enough to cool
the ignition source and prevent the gas path from igniting back to the burner.
After a few runs it will become second nature to not boiler
steam pressure and water level as well as tender water bath temperature and
Keep listening for any mechanical sound that was not
audible during the last run. If the
locomotive was lubricated properly, squeaks will not occur. The villain will be clicking or clanking noises.
This is probably due to fasteners that have come loose.
When such noises are heard, sideline the locomotive, shut it down, and
investigate until a cause is found. Remember
that Frank S. is an unsprung locomotive and all irregularities in the road bed
are transmitted by vibration full strength into the chassis and thus to all
If a Goodall valve is fitted, and boiler water level is properly maintained, the end of the run will be signaled by a gradual loss of boiler pressure and sound from the burner as the locomotive runs out of fuel.
A sudden and dramatic stop is an indication of no water in
the boiler, and this can happen in a boiler not fitted with a Goodall valve.
Ideally, a locomotive should run out of fuel before running out of water,
but this is not the case with Frank S. and so extreme care must be taken to
prevent this from happening. A good
rule of thumb is to follow for a boiler not fitted with a Goodall fill valve is
to fire the boiler for no more than 20 to 25 minutes, including steamup, before
shutting down, cooling down and refilling.
As pressure drops, shunt the fuel less locomotive off the mainline and prepare to shut it down. Add distilled water to the boiler via the Goodall valve. If your boiler is not equipped with a Goodall valve make sure that there is no remaining pressure in the boiler by venting the pressure relief valve.
Now add distilled water through the boiler fill fitting until ¾ of a glass is visible. This added boiler water helps to cool the boiler and to prevent the condensing residual steam from pulling a vacuum on the steamlines with the chance of sucking steam oil out of the lubricator and back into the boiler. As the boiler cools, the water level will drop to ½ glass as the water molecules contract. Now is the time to open the Roscoe displacement steam oil lubricator supply tank, suck out the condensate, and top off the tank with fresh steam oil. Once again the use of those slender scientific supply house plastic pipettes really eases this job. I reuse them by cutting a ½” diameter hole in the lid of a clean yogurt container and stocking the used ones in to drain.
Cap up the steam oil tank and move on to the tender water
bath. Syringe out the warm water
surrounding the liquid gas tank and leave it empty to cool.
If you want to refill it immediately, add cold water to the bath and
charge the tank with liquid gas from a warm storage container.
As you may remember from part one of this series, fuel, either liquid or
gas, will only transfer from one container to another when there is a difference
pressure between the decanting container and the receiving container.
Cooling the tender fuel tank aids this process.
Wipe the locomotive and tender down with a clean, lint free cotton rag. Full-scale locomotives are rarely pristine and a little oil gleaming on the boiler casing looks macho. If will pay to lubricate all the moving parts of the chassis, tender, and motion prior to the next run, and this is a good time to do so. Recheck all fasteners on the locomotive and tender for tightness.
This series of articles were originally published in Steam in the Garden. Appreciation is expressed to both the author, Kevin O’Connor, and Ron Brown, Publisher/Editor, for permission to post to the SouthernSteamTrains.com web site.