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Fuel Systems

 

Aster locomotives are fired by alcohol, butane gas or coal.  Fuel choice is a major factor in determining what type of boiler will be selected for a miniature locomotive.  While denatured alcohol is probably the most common fuel for Gauge 1 steam locomotives, gas and coal are viable alternatives.  Each fuel has its advantages and disadvantages.  The chart contains comparisons.  A discussion of each system follows.

 

 

ALCOHOL*

BUTANE GAS

COAL

SAFETY

Extremely Safe

Safe

Extremely Safe

FUELING

Not temp. sensitive

Very temp. sensitive

Not temp. sensitive

BURNING

Irritates eyes

No eye irritation

Irritates eyes

FAN

Required **

Not required

Required

BLOWER

Required**

Not required

Required

 

* 200 proof denatured ethyl alcohol gives the best results when the burner wicks are in good condition and properly trimmed.  It can be purchased from a chemical / scientific supply dealer.  Methyl alcohol vaporizes and burns at a lower temperature than ethyl alcohol.  However,  it is also satisfactory for use in Aster locomotives.  The key point is to use a fuel which is free of water.  Ethyl or methyl alcohol purchased in paint or hardware stores may contain up to 9% water.

** Not required for a vaporizing alcohol burner system with a pot boiler.  (see Figure 43 in Alcohol section)
Alcohol

Most Aster locomotives are fired by denatured alcohol using either a forced draft wick burner or a vaporizing burner.  USE ONLY DENATURED ALCOHOL.  200 PROOF DENATURED ETHYL ALCOHOL WILL GIVE THE BEST RESULTS. When adding fuel to a locomotive which is under steam, close the fuel tank needle valve and extinguish the burner.   After this is done, fuel can be added to the tank either by means of a funnel or by a squeeze bottle. 

TO AVOID INJURY, NEVER ADD FUEL TO AN ASTER LOCOMOTIVE FIRED BY ALCOHOL UNLESS THE FIRE IS EXTINGUISHED AND THE FUEL TANK NEEDLE VALVE IS CLOSED.

Figure 40 shows a typical forced draft wick burner fitted to a Gauge 1 locomotive.

Figure 41 illustrates the tools required to operate it.

This system requires a draft so that there is sufficient oxygen to maintain combustion. If the boiler should run dry, the draft caused by the exhaust ceases and the fire will quickly die out.  Inspect the wicks and silicone tube connecting the burner and alcohol tank to insure they are in good conditions.  Replace if necessary. 

 

The needle valve on the fuel tank should be closed, the filter plug removed and the tank filled to its specified capacity using denatured alcohol.  Be sure to immediately replace the cap on the fuel supply can, since alcohol will absorb water from the atmosphere.  Replace the filler plug and tighten it unit its O-ring begins to distort.  Put a drop of oil around the plug / O-ring after it is tightened to insure an air tight seal.  The fire is not ready to be started. 

 

1.  Place the suction fan in the stack and start it.

 

2.  Make sure the locomotive regulator is closed

 

3.  Open the needle valve on the alcohol tank one turn.

 

4.  As the wicks soak fuel, check for leaks.  If the wicks overflow, close the needle valve and check the filler plug to be sure it is making an air tight seal.

 

5.  Light the wicks using the igniting bar.  The can be more easily accomplished if a stand is use which raises the locomotive up about twelve inches and which has a large hole directly beneath the burner wicks. 

 

6.  Check the burner flame by means of a mirror.  The flame color should be predominately blue.  If the color is predominately yellow, the fuel is contaminated and should be replaced.

 

7.  When the pressure gauge reads 2 kg/sq cm, crack open the blower and remove the suction fan.

 

8.  When the safety valve blows, set the valve gear for forward running.  Wit the regulator slightly opened, roll the locomotive forward for a few feet to clear the cylinders.  KEEP YOUR FACE AND HANDS AWAY FROM THE STACK AS HOT WATER AND OIL WILL BE EJECTED.  Close the regulator.

 

9.  Couple the train to the locomotive and open the regulator so that that the load can be pulled at a reasonable speed.  Close the blower.  Have people stationed along the track to slow the locomotive in case it "runs away."  

 

10.  When the locomotive is stopped, immediately open the blower so the fire will have sufficient draft.

 

11.  When operating a compound locomotive, such as the BR-96, the low pressure cylinders require a brief period of time to warm up and the locomotive will run somewhat slowly until it begins to "compound."  When the low pressure cylinders are warmed, the locomotive's speed will suddenly increase for a given regulator setting, so car must be taken to avoid a derailment.  The locomotive should be warmed up on a straight portion of track, running back and forth, for a few minutes.  Then it can be connected to its train and the proper regulator setting selected for the load to be hauled.

 

It is always necessary pull a heavy train other wise the locomotive will accelerate to a high speed and derail.  The track's curves should be slightly banked and the rust must be free of grease and oil.  Freight cars can car loads, such as small castings or electric motor armatures, which will increase the train's weight as well as add realistic detail.  The heaviest cars should be coupled nearest to the locomotive.  Be sure all cars couplers are in good condition and will not come open or fail during operations.

A vaporizing burner, as show in Figure 42, is used on some Aster models,

which utilize pot boilers such as the BR-86. 

Operation of this system is very simply since a forced draft is now required.  The pilot light heats the nozzle tube and vaporizes the alcohol, which then burns with a very hot flame.  A vaporizing burner does not have the automatic fire extinguishing feature, as does a forced draft system.  Care must be taken to prevent the boiler from running dry.  If it should, immediately close the fuel tank needle valve.  The burner will be extinguished in a minute or so.  NEVER ADD WATER TO AN OVERHEATED BOILER.  Let the boiler cool for about 20 minutes before refilling it.

Another style of vaporizing burner, which is also called a blow lamp, is show in Figures 43.   It consists of two major parts, the main blow lamp burner and the preheating burner.  The alcohol tank becomes pressurized after being heated by the preheating burner and blows a stream of vaporized fuel through the nozzle where it is ignited by the preheating burner.  This type of burner is most suitable for a center flue boiler.  Both the main and preheating burner tanks should be filled to no more than 80% of their respective capacities to avoid fuel waste and spillage.  The main tank is fitted with a safety valve to limit pressure.  The performance of this system varies with ambient conditions.

  

Figure 44 shows different nozzle settings which result in different flame intensities.  The position of the nozzle determines how much air mixes with the vaporized alcohol and the temperature of the resulting flame.  In general, the greater amount of air in the mixture, the hotter the flame of will be. 

 

NEVER USE GASOLINE OR PAINT THINNER AS FUEL SINCE THEY COULD EXPLODE AND CAUSED DAMAGE AND INJURY.  USE ONLY DENATURED ALCOHOL. 

Butane Gas

Butane gas is sometimes used as fuel for Gauge 1 locomotives and several Aster locomotives, such as the C&S Mogul and Climax, employ it.  Figure 45 shows the typical butane gas system.  It is most suitable for a center flue boiler. 

 

ASTER LOCOMOTIVES WHICH ARE GAS FIRED, ARE INTENDED TO BE FIRED ONLY BY BUTANE GAS.  NEVER USE PROPANE GAS OR A PROPANE / BUTANE MIXTURE AS A SUBSTITUTE SINCE AN EXPLOSION CAUSING SERIOUS DAMAGE AND INJURY COULD RESULT.  

 

Gas fired locomotives are sometimes fitted with an axle driven feed water pump and a bypass valve, which when properly adjusted, keeps the boiler water at a constant level.  If the water level falls below the flue level, the boiler will be seriously damaged.  The water level should be constantly checked to assure the proper level is maintained.

A butane tank pressurizes when it is filled.  The pressure of the gas is a function of the temperature of the fuel tank.  When the tank is first filled, the pressure may be quite low if the fuel system is relatively cold.  When the regulator valve is opened, butane gas flows through the nozzle mixes with air and flows to the burner. Aster locomotives situate the main fuel tank in the water reservoir. 

 

For the day's first run, the proper amount of butane should be added to the tank before any water is added to the reservoir.  Next, fill the reservoir with WARM (NOT HOT) water.  This will cause the butane in the main tank to pressurize so that the burner can be easily lit and will remain lit while the fuel system "warms up."   Once the fuel system is warm it will provide a stabilized flow of butane to the main burner.  Any additional water added to the reservoir can be cold.   

 

The tiny jet in the main burner should be frequently cleaned by means of a small wire "pricker."  Care should be taken not to enlarge the diameter of the jet.  The burner is usually lit through the smoke box or the stack.  The burner must be correctly adjusted to assure proper combustion.  A reduction of intake air will reduce noise, but may not result in proper combustion.  If butane an be smelled, the intake air flow must be increased.  Correct adjustment will maximize heat generation.

  

Not all Aster burners allow for adjustment with the burner on the C&S Mogul being an example.   If the burner lights but will not stay lit, the problem is most likely a cold fuel system.  On locomotives which are fitted with a preheating tank, such as the C&S Mogul, it is best to first open the valve between the preheating tank and the burner.  This is done when the locomotive is initially steamed and before opening the main fuel supply valve on the tender.  After the preheating tank has had a chance to "warm up," its valve can be use to control the fuel flow.  If the burner goes out immediately shot off the fuel supply and let any gas dissipate.

  

Keep spectators, especially children away from the locomotive.  Add warm water to the water reservoir, as described above, and re-light the burner.   When butane tanks are filled, it is common for a small amount of gas to escape and surround the locomotive.  For this reason, never attempt to fill a tank unless the fire has been extinguished and the locomotive is situated away from the main line where other locomotives are operating. thereby preventing flash burning.

  

Prior to filling the main fuel tank, inspect the system for damaged hoses and /or O rings.  Replace as necessary.  If there is evidence of frost on the hose or fitting this is an indication of a leak.  DO NOT ATTEMPT TO STEAM THE LOCOMOTIVE UNTIL THE LEAK HAS BEEN LOCATED AND ELIMINATED.    OTHERWISE, A FIRE COULD OCCUR. 

 

Hose replacements should be rated for high pressure.  Aster recommends only the use of Aster replacement hose with wire shielding.  The vapor pressure of commercial butane gas varies from 7 psi at 10 degrees C; to 31 psi at about 21 degrees; to 97 psi at about 54 degrees C;  to 180 psi at 100 degrees.  Butane is a safe efficient fuel, but like any fuel, whether solid, liquid or vapor, it must be handled with respect and care.

Coal Firing

Some Aster locomotives, such as the JNR C62, are fitted with locomotive type boilers, which may be fired by coal or alcohol.  When fired by coal, the alcohol burner is removed and grates are installed at the bottom of the fire box.  The figure below shows the typical equipment and tools need to fire a locomotive type boiler

Firing such a small boiler is quite interesting and challenging, since grate area may be as small as 47 mm by 64 mm, while the fire hole is only about 20 mm in diameter.  If low quality bituminous coal which is used to heat houses, is burned in a small fire box, the tubes will soon become plugged and clinkers will form on the grates.  The fire will be weak and unable to generate steam in the boiler.

 

The best coal for small seam locomotives is Welsh steam coal.  If it is not available, anthracite coal or hard charcoal, known as "Bincho" in Japan, can be used.  Hard charcoal will supply sufficient heat to steam the boiler.  If a little coal is also added to the fire, the aroma of a coal fire will be simulated.  The charcoal should be broken into small pieces about the size of a fingernail.  The pieces must not be too small or they will fall through the grates.  Lighting a hard charcoal fire may be difficult.  After the locomotive's bearings are lubricated and the lubricator and boiler filled to the specified limits, the following procedure can be used to start the fire.

 

1.  Place the charcoal bits evenly on the grates to a height of about 2 cm.  Pace a suction fan in the stack and turn it only.

 

2.  Ignite an alcohol blow lamp burner and play the flame on the charcoal and the smoke tubes.  Continue to do this until the pressure gauge shows 1 kg/sq cm and the charcoal glows red.  

 

3.  Close the fire box door and crack the blower valve.  Remove the suction fan from the stack.  After a few minutes, steam pressure should be rising.

 

4.  Open the fire box door and add additional charcoal evenly to the fire.  Close the door and listen for the fire to make a cracking sound.

 

5.  When operating pressure has been reached, the safety valves will blow.  The color of the fire should be yellow, which signifies excellent combustion.  The locomotive can be connected to the train and operated.

 

There are other methods of starting a fire, such as the use of an extension chimney and a foot operated bellows.  Soft charcoal pieces can be lit on a outdoor grill and then even placed on the grates in the fire box.  The door should be closed and bellows operated until the pressure gauge shows 1 kg/sq cm.  The blower should be cracked open and hard charcoal added evenly to the fire.  Remove the bellows and extension chimney and wait for the safety valve to blow.  Add additional charcoal as necessary.

 

Experienced operators can start a charcoal fire directly in the fire box by stacking soft charcoal evenly on the grates and laying oil soaked wood chips on top.  Once the fire is burning, hard charcoal is added.  A coal fire in a Gauge 1 locomotive does not yield constant heat, as does an alcohol or gas fire, because the heat release of the burning coal follows a cycle.  Firing the locomotive, so that long runs can be made, is an indication of the operator's skill and provides a significant challenge to both the beginner and the experienced live steamer.

 

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