Models with real boiler installations

[Derek Warner]

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> The exhaust steam from each engine goes into a little manifold I have made
> from tube and thence to an oil trap/condenser. The output from the
> condenser is then piped into the funnel so that the rising heat from the burner
> exhausts it, fresh and clean, to the atmosphere
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Yes it's me again Stuart - Derek with more questions

In the shot "Reliant drive 2" - I see the lagged pipe from the boiler steam dome returning,
then in shot "boiler piped" - I see the same lagged line returning to the boiler

So I looked in my 1973 text "Heat Engines & Applied Heat" (ISBN0304298015) and found
on page 168 - the reason for the return of steam to the boiler is "to super heat it" - "the
things you forget after all these years!"

So irrespective of the size of the boiler or pressure the same principal applies - to get
the steam to do some (more) work we must make it hotter ie., expand it>>

So is that what the Cheddar designers are providing? - as I see another lagged line from
the same area (full length reversal) branching out as steam supply to both engines
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Condensing - I have re-read the principals from the above text, however I would have thought
the exhausted "steamy/oilywater/condensate" from simple marine model applications would
go directly to the boiler flu with the hot boiler gases providing a venturi effect and pulling
condensate up without the need to pump it?

So in real life, steam condensers do have a pressure side and a side with potential for vacuum,
what do model condensers do? - I looked at some associated Chedder sites & noted
photoghaphs & text of model ship condensers, but there was no mention of the need to
surface condense (under water cooling tubes) or reuse water via make up pumps etc

Decoy is listed as having a "common, non condensing, direct acting, diagional steam engine"
so I can only assume she had some sort of make up pump to slurp up great volumes of the
sometimes muddy river Murray for her boiler to injest - again from old photographs I can
only assume steamy/oilywater/condensate went straight overboard

In older or current model stream trains, does this same steamy/oilywater/condensate not just
expelled to atmosphere??
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Decoy had an open boiler room, simply covered by the deck above, (so the planned fake boiler
- smoke generaator would have been in full view) - the problem with the real Puffin horizontal
boiler is that I would have to move the existing bulkhead between the boiler room & the FWD
hatch by some 25 mm - however the axis of the funnel would amazingly be less than
1/16" out!! - so apart from that no problems

Decoy reportedly had a hot box of an engine room, so without too much licence I could
provide port, stdb & fwd viewing of the Puffin twin in the engine room again under the same deck

Decoy was chosen to model so as to provide the splash of paddles, the view of the (fake)
boiler & plenty of boiler smoke etc - but now Stuart's postings have provided the extra
potential of reality - but have you seen the little aussie $ rate against the $US or your new
EURO!!

regards Derek

[Derek Warner]

on Sunday, April 07, 2002 11:01 PM Stuart Badger wrote

Decoy would, I expect have been fitted with a feed pump to pick up river
water - and I expect the boiler had to have the inspection plates regularly
removed to 'de-gunge' the boiler!.

Do you know who the builders of Decoy were and when she was shipped out in
kit form to Oz??
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Thanks for your response again Stuart

In certain text's that I have read suggested paddlers on muddy rivers did require this facility of
opening the boiler casing and cleaning the boiler tubes after an apparent loss of steam - further
the salinity of lake Alexanderina (near the Murray mouth) would have compounded boiler issues
for vessels plying that area - I can only assume that you will be using distilled boiler feed water?

My listing nominates that Henderson & Co from Renfrew (Scotland) were the builders (hull
components and engine) - I suspect that the engine would have been fully assembled & tested
then shipped out with the pipework as loose supply - I do not have an understanding of the level
of hull plate trial fitment in Scotland, however she was reassembled in June 1878 by Forman &
Co in Melbourne (Australia)

regards Derek

[Derek Warner]

on Sunday, April 07, 2002 11:01 PM Stuart Badger wrote

The condenser/oil trap on the exhaust side of the engines is almost entirely
for environmental reasons. You are quite right to say that the oil/water
exhaust would simply be carried away up the funnel by the heat of the
burner - but it would settle out of the atmosphere onto the water causing
damage to wildlife and plants
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Thanks Stuart, and all of this makes sence etc - but?

I understand we are taking exhaust steam with say less than 0.5% lubricating oil mist
into a non pressurised container to condense (as water with minute steaming oil %
sitting on top)

I have spent a few hours over the past evenings trying to understand how the condensed
water component gets to the boiler chimney hot gasses to be burnt off without pumping

Also it didn't matter how many weir or baffle plates I sketched in the container, I still
ended up at some stage with the minute steaming oil % going up the stack again

One of the sites associated with Cheddar showed steam plant marine models with grey
painted "condensers" but explained no detail

I am intrigued - regards Derek

[Stuart Badger]

Hi Derek

I see where you are coming from with your comments about the oil/water. I
must admit I found this strange myself until I SAW what comes out of the
condenser when one 'blows out' ! The steam oil emulsifies with the water
and forms an unholy gunk - I think one of the properties of steam oil is
that it has an ability to emulsify but still lubricate. After about 10
minutes running time there is about 20ml of thick emulsified oil. I presume
the steam/water vapour that is exhausted is the non oil saturated component.

Perhaps it's better to think of the can as an oil separater rather than a
condenser?

Stuart