ventilation of lighting heat in multi-level layouts
wat...@delphi.com
If anyone else is doing any work on venting the heat of lighting systems on
multi-level layouts, please correspons with me. I built up a closed cube of
one square foot with connections for x-mas tree lights, 7.2 watt, 15 watt and
25 watt bulbs (the x-mas tree unit had 3 bulbs) and each in turn was turned on
for 6 hours with a recording thermometer inserted. This was done with the box
closed, and again with 3 sq inches of open vent, --no fan, and found all
combinations to generate increases beyond safety, Irealise no layout has
a closed system, but this gave control to the experiments. The 25 watt
bulb went to over 300 degrees after 5 hours...that is not far from the
flash point of paper. even the 7.5 watt went over 240 in the vented system.
Now WHO has an idea of a better designed experimental system or has lucked up
on a usable system.
My next tests are being done with 24 volt DC lamps that are intended for use
in walkway and yard locations.. they seem to burn much cooler though the
lumen output is low and I know of no colored bulbs.
Snowsnake. Frank Watson..... Valhalla & Styx Railway
Stephen Kay
Remember that a 25 watt lamp is a 25 watt HEATER also! I suggest you
look into compact fluorescent lamps--Some of these are 13-20 watts but
put out the light equivalent to a 60-75 watt lamp. Compact fluorescents
are sold as "Earth Lamps" and such. Should be available at Builders
Square, Lowes, etc.
-
STEPHEN KAY GPJ...@prodigy.com
Mike Dodd
wat...@delphi.com wrote:
>I built up a closed cube of
>one square foot with connections for x-mas tree lights, 7.2 watt, 15 watt and
>25 watt bulbs (the x-mas tree unit had 3 bulbs) and each in turn was turned on
>for 6 hours with a recording thermometer inserted. This was done with the box
>closed, and again with 3 sq inches of open vent, --no fan, and found all
>combinations to generate increases beyond safety, Irealise no layout has
>a closed system, but this gave control to the experiments.
I believe that your test is flawed.
You are correct -- no layout has a closed system, and this is the key
point. Don't underestimate the dissipating power of open air. When
air becomes warm, it rises and mixes with cooler air. It doesn't sit
in a closed box.
How well insulated was your box? If you take a perfectly-insulated
box and keep pumping heat into it (1 watt, 15 watts, who cares?), the
temperature will continue to rise until it reaches the filament
temperature. Is this a realistic test? What does it tell you?
Your box was 1' x 1 'x 1' = one cubic foot. Suppose you made it the
size of a typical room, say 12' x 12' x 9' = 1,296 cubic feet. How
hot would it have become with those bulbs in six hours? You'd
probably not notice the difference at all. Just consider your own
bedroom, which probably has a couple of 60-watt bulbs -- does the
temperature "increase beyond safety?"
The point is that surrounding a bulb with a small, somewhat-insulated
box doesn't really tell you anything. If you're concerned about
lighting under the top level of a two-level layout, perhaps you should
build a full-size model and try some experiments with it. If what you
are trying to do is illuminate the railroad room, then either don't
worry about it (or talk to an architect or lighting specialist if
you're planning to install kilowatts of lighting).
========================================
Mike Dodd Virginian & Western Railway
md...@rmond.mindspring.com
========================================
PETER PAN
In article <5jAvOQs...@delphi.com>, wat...@delphi.com writes:
>If anyone else is doing any work on venting the heat of lighting systems on
>one square foot with connections for x-mas tree lights, 7.2 watt, 15 watt and
>25 watt bulbs (the x-mas tree unit had 3 bulbs) and each in turn was turned on
>for 6 hours with a recording thermometer inserted. This was done with the box
>closed, and again with 3 sq inches of open vent, --no fan, and found all
>combinations to generate increases beyond safety, Irealise no layout has
>bulb went to over 300 degrees after 5 hours...that is not far from the
>flash point of paper. even the 7.5 watt went over 240 in the vented system.
>Now WHO has an idea of a better designed experimental system or has lucked up
>on a usable system.
>My next tests are being done with 24 volt DC lamps that are intended for use
>in walkway and yard locations.. they seem to burn much cooler though the
>lumen output is low and I know of no colored bulbs.
>Snowsnake. Frank Watson..... Valhalla & Styx Railway
I would recomend going into a radio shack and buying a small cooling fan. Or
you can buy two. I think that they are rather quiet, and you can use one for
intake of cooler air and one for the exhaust of the warmer air.
Dennis Rockwell
In article <DuLn8...@mv.mv.com>, Dick Lord <r...@sesame.curtech.com> wrote:
>Lighting for a lower deck, enclosed in the framing of the upper deck is
>contained in a 5-sided box with the opening at the bottom. While part of
>the radiated heat does escape downward, ALL of the convective heat and HALF
>of the radiated heat will be trapped under the scenery of the upper deck.
Which sounds like a fine reason to use the well-known
scenery idea of hiding your base-to-backdrop transition
behind a small rise or some such thing. If you leave space
between them, it will serve as (at least some) ventilation.
Beware: cobwebs blowing upwards in front of your backdrop
spoils the illusion!
--
Dennis Rockwell den...@osf.org
Open Software Foundation +1-617-621-7268
_______ _______ _______ _______ _______ _______
####(|oo=oo||_______||_______||_______||_______||_______||_______)#####
I love the smell of brakeshoes in the morning!
David Ramos
Hi Frank
Allow me to comment on your Ventilation of Lighting Heat posting:
First, your test is doomed to failure because you have established
conditions
beyond what even a flourescent lignt (with ballast) could handle. What
you've
created is called an OVEN! You have to remember that any light bulb
converts
most of the electricity it uses (about 90% if I remember correctly) to
heat. NO
bulb can take being shut up in so small a space with only a single 3 sq.
in.
hole for ventilation without overheating. You are darn lucky you didn't
start a
fire, you'd have been very embarrassed when the fire marshall and insurance
agent started laughing at you. PLEASE don't try that again.
If you look at ANY lighting fixture made by a professional you'll see that
there
is some method built into it to allow ventilation in more than one place.
Even
in fixtures that appear to be sealed usually have some sort of baffled
vents
distributed around the fixture to allow air to circulate through. A fairer
test
would have been to provide 9 - 1 sq. in. vents (Note the same area, but
properly
distributed), some at the bottom and some at the top, so that air could be
drawn
through the box. I am NOT suggesting trying that stunt again but if you
did I'm
sure you'd find the temperature inside the box would be much cooler.
It is extremely important for saftey reasons to allow some sort of method
to
ventilate the fixture. Even a bare light bulb in a porcelain socket
attacted to
the cieling ventilates itself. The heat from the bulb heats up the air
around
it, causing it to rise and spread out along the cieling. This causes
cooler air
below the bulb to be drawn up and heated in turn, cooling the bulb in a
constant
cycle dissipating the heat. That's why the room gets warm all over instead
of
just around the bulb.
Even on fixtures made of metal, you'll usually find vents around the base
of the
fixture where the socket is mounted. This is so heated air within the
fixture
can escape upwards and draw in cooler air from below. It's a process
called
convection. To be UL listed, as an example, a fixture must be able to
allow
enough convection to keep the ambient temperature of the fixture below a
certain
temperature. That's why a fixture like a desk lamp is often rated for 60W
or
less bulbs, though the wire and components it's built from are probably
rated
higher.
A metal housing also helps to keep the bulb inside the fixture safe by A)
surrounding it in a non-flammable ventilated container, B) metal is an
excellent conductor of heat, both wicking it away from the bulb and
radiating it
to the air outside, C) it protects stray arms and fingers from
accidentally
touching the extremely hot bulb inside.
In your development, I strongly suggest you take care not to build a
fixture in
a flammable housing, or that will directly contact something flammable. If
you
leave ample vent holes around the fixture, you should not have any problems
with
instruments overheating and starting a fire. Cooling your space, however,
may
be a problem if you use a LOT of lights. I also suggest that more fixtures
with
smaller wattage are probably safer and more aesthetically pleasing than
fewer,
stronger fixtures.
If you like I'll be happy to send you a 'white paper' I'm working on
regarding
building safe, 120V low-wattage layout lights with commercially available
parts
obtainable at any home products or hardware store. It's not a finished
article
but you might find it helpful. That goes for anyone else interested too --
just
send me your EMail address and I'll fire off a copy to anyone interested.
Please bear in mind it is copyrighted material. It will also be available
in a
couple of weeks, with illustrations, on my website:
http://ourworld.compuserve.com/homepages/cbisgeier. And in the TrainNet
forum
library too.
My current experiments are in really low-voltage fixtures, centered around
12
volt automotive fog light halogen bulbs. they are not the cheapest
solution but
they should be relatively safe and low-heat, with adequate and even
coverage. I
have not progressed far enough to report on this yet but when I do I'll be
sure
and post something about it. I am actively recruiting suggestions for a
cheap
and easy to obtain / modify metallic, ceramic or other non-flammable
material
pseudo-parabolic reflector, approx. 4 - 5" in width... Any suggestions
greatly
appreiciated...
You will probably not have much luck with the 24v outdoor lights. I have
heard
of others who have tried them without success, they are too expensive,
bulky and
not bright enough.
I am also developing a lighting design for a multi-deck layout, and I'd be
happy
to share my experience and ideas with you. My scheme will probably be a
combination of methods, using floodlights from the aisle areas and strings
of
long but narrow striplights made from mini-Xmas lites with a metal
reflector
mounted behind the fascia edge... Mutiple rows of striplights might be
used in
deeper areas to provide even coverage... Possibly even extra colored
striplights
interspersed for dawn-dusk-night effects. The striplights will have to be
low-heat or insulated because they will be mounted next to styrofoam boards
used
to make the scenery base and subroadbed.
Frank -- please don't put yourself at risk any further. I'd hate to read
about
you in the paper.
Craig Bisgeier
72724...@compuserve.com
Asst. Sysop for Model RR Layout Design, CompuServe TrainNet forum
(And Former theatrical lighting electrician)
--
Fowarded BY:
David Ramos
Rick Vera-Burgos
In reply to Frank's posting which has expired on my system so I can't quote
it:
An idea occurs to me, but without some construction experimentation I can't
speak to it's difficulty (or expense). It seems to me if you built your upper
level with a backdrop other than the wall, with some space (I bet as little
as an inch would do it) between it and the wall, you could construct the
bottom of the upper level (over the lower level lighting) in such a was as to
"spill" the hot air behind the upper level backboard and in front of the
wall. This is assuming that your upper level lighting/valence/whatever was
set up to be ventilated adequately too. In case you're thoroughly confused,
I'll try some ascii artwork (turn off your proportional fonts):
-------------|
|^ | 0| <---- upper level lighting
|h |
|e | <-upper level backdrop
|a |
|t |
| ---------\
| o| <--- lower level lighting
| <- wall
|
|-----------| <--lower level
| |
If this is in a basement, you could just leave an open space in the lower
level backdrop (drywall or whatever) at just below the bottom of the upper
level, and again just below the ceiling and achieve the same effect.
Obviously, any of this would complicate construction, and without actual
experience, I couldn't tell you if it's worth it. Just an idea for folks to
chew on...
--
Rick Vera-Burgos
Div. Supt. B&O Cumberland Division East End (under construction)