An Improved Method of and Apparatus for Maintaining a Uniform Temperature in Laboratory Ovens, Incubators, Drying Rooms, and the like.
Year: 1896

page_text: Date of Application, 7th Sept., 1896-Accepted, 24th Oct., 1896
[Communicated from abroad by ADOLPH SCHWABE; of 49 Koniggatzer Strasse,
Berlin, in the Empire of Germany, Manufacturer.]
An Improved Method of and Apparatus for Maintaining a Uniform
Temperature in Laboratory Ovens, Incubators, Drying Rooms,
and the like.
I, WILLIAM ROBERT LAKE, of the Firm of Haseltine, Lake & Co. Patent
Agents, 45 Southampton Buildings, in the County of Middlesex, do hereby
declare the nature of this invention and in what manner the same is to be
performed, to be particularly described and ascertained in. and by the following
statement:-
This invention relates to a method whereby the temperature of the atmosphere
in an enclosed space may be automatically maintained, at a-pre-determined, degree,
and consists in bringing fluid into as close a contact as possible with the atmosphere
of such enclosed space, the temperature of the fluid being automatically maintained
constant in the following manner :-
The fluid is heated from a constant source capable of supplying it with more
heat than is required to keep up the desired temperature, the hot gases emanating
from the source of heat being so directed, that they envelope, or flow in contact
with, the walls enclosing the fluid: In the fluid; a float is arranged'; such float
being connected with a valve in such a manner that, whenever the float sinks, the
supply of hot gases is "throttled" or checked, and whenever it rises, such gases
are allowed to pass freely. As the temperature of the fluid rises beyond the
requisite standard, or limit, its specific gravity decreases, the float descending-in
the liquid' for a corresponding distance and checking the hot gas supply. But as
soon as the temperature is again lowered, in consequence of the reduction of the
heat supply, the specific gravity of the fluid increases, the float, rises; and the gas-
inlet is re-opened. It is necessary that the float should be so weighted that, when
the temperature within the chamber is normal; the float may be freely balanced in
such a position that the loss of heat will be precisely compensated for by the influx
of the heat from the heating gases supplied..
The apparatus which I consider. best adapted for the purpose above described,
is represented, by way of example, in the accompanying drawing, wherein
a designates the chamber or space the atmosphere of which it is desired to maintain
constantly at a pre-determined temperature. The chamber a is, on all sides,
enclosed or surrounded by double walls, the intermediate space (or jacket) between
being filled with water or any other suitable fluid. This fluid-jacket is in com-
munication with another fluid reservoir b, surrounded by the above-mentioned
chamber a; and in this reservoir b is placed the float c, which may be of any
suitable construction. From the float is suspended a chain passing down through
a tube f, and to the lower end of such chain is attached a hollow cup or ball g
containing shot or other weights and hanging over an orifice provided in the
heating chamber h.
The complete apparatus is enclosed in a case i, the walls of which, in conjunction
with the outer wall of the fluid jacket, form the heating flue, which is provided.
with outlet orifices at the top. The float is exactly weighted to ensure the
maintenance of the desired temperature in the chamber or space a. As a heating
medium, a gas flame or other convenient source of heat may be used, and this is

page_text: located in the lower space h. The hot gases rise through the orifice below the
ball g and flow upward around the walls of the fluid-jacket enveloping it on all
sides, and yielding up their. heat to the chamber a as they pass.
The moment the specific gravity of the fluid decreases owing to an undue
increase of temperature, the float sinks and the ball-shaped valve g closes the gas-
inlet orifice. This enables the apparatus to cool down again to such an extent
as to allow the fluid to become sufficiently dense to cause the float to rise again,
with the result that the ball-shaped valve galso rises from its seat to a proportionate
extent, thereby widening the aperture of the inlet and allowing proportionately
more heat to be supplied.
By means of the method and apparatus above described a constant temperature
may be maintained. This invention is applicable to ovens or chambers for
chemical laboratories, as it enables such pre-determined temperatures to be
maintained as are required for certain chemical reactions. The apparatus described
may also be utilised as an incubator. Again, comparatively large spaces, or
rooms, such as warehouses, drying-rooms, kilns, &c. used in the different
industries, may be uniformly heated by this improved method.
Having now particularly described and ascertained the nature of the said inven-
tion and in what manner the same is to be performed, as communicated to me
by my foreign correspondent, I declare that what I claim is :-
1. A method of maintaining uniform temperatures in closed spaces or chambers,
mainly consisting in submitting such spaces or chambers to the heating action of
a quantity of fluid the temperature of which is maintained constant by causing hot
gases to flow in contact with the sides or walls thereof, the admission of such gases
being checked by means of a float, balanced in the fluid, whenever a pre-determined
limit of temperature is exceeded, and vice versa.
2. Apparatus for carrying out the method referred to in the first claim, con-
sisting of a space or chamber such as a surrounded by a fluid-jacket, and of a float
balanced in the fluid; which float, whenever the specific gravity of the fluid decreases,
sinks lower down and through the medium of a ball or cup, such as g, filled with
shot or other weights, closes the heating gas inlet, substantially as and for the
purposes described.
Dated this 7th day of September 1896
HASELTINE, LAKE & Co.,
45 Southampton Buildings, London, W.C., Agents for the Applicant.