Evening star., 1926-11-20
REAL ESTATE
OIL BURNERS TESTED BY US.
RESULTS ARE GIVEN TO PUBLIC
Careful Investigation of Different Types
Advised-Grade of Fuel Used and
Boilers Stressed.

In response to a general demand for
information on oil burners for house
heating the United States Department
OF Agriculture has tested a number OF
oil burners Of different designs and
prepared the following Information tC
assist the home owner in deciding II
II is advisable to install such a burner
and the type to install.
Heating with such burners appeals
to many home owners because of the
relief from furnace attendance. dirt
the uncertainties of coal supply and
the ease Of heat regulation. Different
types Of burners have been placed or
the market and the tests conducted by
the department and a study OF many
installations indicate the character Of
performance that may be expected o1
the different types Of burners. the
adaptability Of existing heating plants
and facts concerning oil fuel supplies
and operation costs.
Different grades Of oil fuels are or
the market and the particular grade
required by a burner is an importa nj
consideration. For the laymen the
gravity Of the oil In degrees of the
A. p. I. (Baume sometimes used
scale Is the best guide. The gravity
is determined with a hydrometer grad
uated in what is called the A. r. l.
scale. high gravity indicates a
light thin oil. while low one indicates
heavier. more viscous oil.
Commercial Fuel Oils.
Oil fuels are commercially known in
most sections as furnace oil. distillate e
fuel oil. gas oil and fuel oil. The com
mon range in gravity is for furnace
oil 3s' to 40'. distillate oil as to 40o
In some sections and 33e to 36o and
% to 35' in others. gas oils 2Se to
3ae and fuel oil 24' to 2s'. all on the
A. p. /. scale. The name Of the oil
does not always indicate It's gravity.
One should know the range in gravity
NJ oil that a burner will use satisfac.
torily and use this information rather
than trade names In purchasing oils
More heating units per dollar Of cost
can be secured from the low gravity.
heavier oils. but they can he used only
with burners adapted for them.
There are on the market a number
~ burners for use in house heaters,
varying in the method employed to
prepare the fuel for combustion. They
may be divided into two general
classes-the vaporiZing, which In
cludes the gravity-feed type. and the
atomizing. which includes those in
which the OIL IL broken up by me-
chanical or spray devices.
This is the simplest type Of burner.
very often consisting merely Of one or
two rough castings which are set IN
side the furnace. and its initial cost
Is low. Some device. such as hot
plate" Ia essential for volatilizing the
oil SO that a vapor will be produced.
The air to support combustion is gen.
orally brought into the furnace by
the natural draft produced by the
chimney. Some rather ingenious
means are used to induce an intimate
mingling of this air with the vaporized
fuel. but In general good combustion
II not secured by this method unless
a highly volatile (high gravity fuel
is used
Manual Control In Some.
While the principle seems simple
enough. the fuel and the air are not
mixed with sufflcient thoroughness to
give good. clean fame. In the
cheapest burners Of this cla ss the CON
troll Is entirely manual: the burner is
started by hand and the control of
temperature Is effected In like manner.
In some cases automatic control has
been applied with apparent success.
The gravity-feed vaporizing burner is
limited to the use of the relatively
high priced fuels.
The atomizing type Of oil burners
may be subdivided into those which
break up the oil by purely mecha nical
mea ms and those which atomize the
oil by spray devices.
In one mecha nical type atomizing
burner tho oil is put under pressure
and forced through a small opening
to break It up into minute particles.
and it enters the furnace as a vapor
spray. Air In supplied by a blower or
pump and so regulated az to bring
about the proper combustion Of the
fuel.
In another tyne of mecha nical
atomiZing burner the oil is broken up
by being thrown from the periphery
OF revolving disc or cup driven by
an electric motor.
The spray type Of atomizing burner
consists Of air and oil nozzles. so ar
ranged that air supplied by a motor
driven compressor blows directly over
the oil nozzle and creates a partial
vacuum. The oil is drawn M from
the supply reservoir by the vacuum
thus formed and is atomized or broken
into minute particles by the air pres
sure in preparation for ignition. The
rate Of feed IL governed by the air
pressure and the size of the nozzle
openings. This principle Is not unlike
that of the ordinary carburetor EN-
ployed In the gasoline engine.
Domestic OIL Fuels.
The oil fuels that are now EN-
pioyed for domestic hea ating are quite
uniform In composition and contain.
roughly. 81 per cent carbon and l3
per cent hydrogen. and oxygen, nj
trogen and sulphur taken together
compose the other per cent. A
mound Of fuel OF this composition re-
ouires about 14H pounds of air for
complete combustion.
Insufficient air supply is one cause
NJ clouds Of dense smoke and SCOT.
sometimes the draft prevailing under
this condition IL not sufficient TO carry
IN the sootv. smoky products Of com
hustton and they permeate the entire
house. with damage to draperles.
hanrinss and household goods. rms
,orr, Of combustion Ia ineff1cient In that
the fuel is not entirely consumed. An
excess Of air is essential to insure sat
iafactorv combustion. In practice pos
siblv rs 10 80 per cent more air Is sup
plied than that which Is Theoretically
reouired. An excess ot air Is also al
yantageous with automatic operation
where the burner Is started and STOP
ned frequently. in that II lessons tne
smoky condition which almost lnVari'
ahly occurs when the burner comes
on"
With the manually controlled graV.
ity burner the hot plate Is preneateo
hv a wick. which Is saturated with OH
end tsnited by a torch. The heat OF
combustion after operation has begun
I. supposed TO vaporize the oil falling
on the hot plate. When the burner Is
ofy for few minutes the plate mus'
he again heated before the oil can oe
Veporized and ignited.
In Some automatically controlled va
..,,inr h,,rners gas flame Is used