¡Improvements in and relating to Pyrometers.
Year: 1893

page_text: Date of Application, 15th Aug., 1893-Accepted, 23rd Dec., 1893
COMPLETE SPECIFICATION.
¡Improvements in and relating to Pyrometers.
We EDWARD A. UEHLING, a citizen of the United States of America, and
ALFRED STEINBART, a subject of the Emperor of Germany, both residing at
Birmingham, in the County of Jefferson and State of Alabama, United States of
America, Gas Engineers, 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:-
The object of our invention is to produce an instrument for accurately and
continuously indicating high temperatures. The principle involved is the law of
the passage of gas or air under a constant forced flow through small apertures.
In the provision of a device for effecting this object its primary feature is the
forcing of air or gas through two successive small apertures, whereby the tension
between them will remain constant so long as the temperature of the passing fluid
remains equal and constant at both apertures; and whereby a change of
temperature at either one or the other of the apertures will also cause a change of
tension between them. If therefore, the fluid as it passes through one of these
apertures, is made to vary with the temperature to be measured, while at the other
it is constantly kept at a certain normal temperature, then the variation of the
tension between the apertures will be a measure of the degree of heat the air has
at the time of entering into the space or conduit between and connecting the two.
apertures, and, hence, of the temperature to be measured.
For carrying out this operation and obtaining this result, our invention consists
of certain novel parts and combinations of parts which are embodied in the
structure illustrated in the accompanying drawings. This structure, however, we
desire it to be distinctly understood is intended only as an illustration of one form
of device embodying our invention, which may be embodied in other and different
forms.
In the apparatus illustrated in these drawings, it will be understood that the
end A' of the tube A, A' is located in the space, or closure, or connected with the
device, the temperature of which is to be determined or constantly indicated, such
for instance, as the hot air blast now universally used in the smelting of iron; or
of an annealing furnace.
For this purpose the inner end of this tube is closed, and is preferably turned up
or swelled. The other end of this tube extends outside of the closure and has an
opening A through which the fluid to be heated enters. Within this tube is
placed a tube a, a, so that there will be a free space all around it. That end which
terminates within the closed end of the outer tube, has a small opening or aperture
at a¹; while its other end which passes through and out of the outer tube, at that
end which is outside of the closure the temperature of which is to be determined,
connects with a coil or worm b, 61, 62, which at its other end, at b³, connects with
the T-couplings, c, c², c², and d, d', d², between which at their juncture, e and d, is
located a diaphragm or thin plate having an aperture similar to that in the tube
at a', within the outer heat transmitting pipe. The T-couplings are connected by
their vertical branches, c, d, with barometer tubes f, and e,
which are immersed
in a suitable liquid in a reservoir F open at i to the atmosphere.
A scale marked off in degrees can readily be attached to the tube f, so that the
degrees of heat can be read off, but any other form of vacuum gage may be used
and graduated suitably for the same purpose.
C is a vessel containing a liquid kept at a constant temperature, preferably water

page_text: at the boiling point or the melting point of ice, through which the worm or coil
passes which forms a prolongation of the inclosed pipe a, a¹.
The operation is as follows.:
The heat receiving tube being open at A and receiving the air to be heated, and
the T-coupling connected with a partial vacuum of constant tension, indicated
by the column e¹ of the pipe e, the hot air from the heated tube A, A', is drawn
through the aperture at a into the inner tube a and through its coiled pro-
longation b, which may, in fact, be of any shape or construction, which offers
sufficient surface to insure a constant temperature, thence through the aperture c
into the partial vacuum which is connected at d¹ to the T-coupling in communi-
cation with said aperture at c. So long as the air which enters at a¹ is of the
same temperature as when passing through the aperture at c, the tension between
the two apertures at a' and c, will remain constant and be indicated by the scale f¹
on the tube and the column therein. Thus, if the end A¹ of the air receiving
tube becomes heated, the air entering the aperture at a' from said heating tube
will assume the same temperature, but in passing through the cooling worm it is
reduced back to a constant normal temperature. This being the case, the
difference of temperatures of the air as it passes the two apertures is due to the
temperature at A¹, and hence the change of tension which results and which is
indicated by the column inf, on the scale f¹, is a measure of the temperature at A².
If, however, the temperature at either aperture is changed, the flow of the gas or
air through the apertures will be changed, and with it the tension between the
apertures, causing the column in f to rise or fall.
The apparatus can be adapted for use anywhere for the purpose designed; and
the degree of heat which it will indicate is limited only by the material of which
the tubes subjected to the heat, are made.
Referring to the registration of the temperature, it will be understood that there
are no thermometer tubes, nor, necessarily, any mercurial tubes in connection with
our pyrometer. Our invention requires simply some form of vacuum gage if the
pyrometer is operated by suction, or pressure gage, if operated by pressure, which
may be a mercurial or any other liquid column, or a spring-gage, many forms of
which are available.
It will also be understood that the action of our pyrometer depends upon the law of
the flow of the gas through small apertures, according to which, if air be drawn
through two successive apertures, by the aid of a common suction, the tension
between these apertures will remain constant, so long as the temperature of the air
remains equal and constant at both apertures, i.e., while flowing through. A change
of one temperature, however, at either one or the other of the apertures will also
cause a change of tension between them. This tension is the measure of the
temperature to be determined. To make this an accurate measure of the tempera-
ture at a (which is the same as that of the space surrounding the enclosing
tube A, A', which may be filled with air, as in the illustration, or with molten metal,
slag, glass or any other substance into which the tube a, a' may be inserted) it is
essential that the air in passing through the aperture c should be of a constant
temperature, and for this reason it is passed through the cooling tube b, while
at a' it varies with the temperature to be measured.
Of course it is well known that gases expand by heat and contract in cooling.
If the temperature of the air passing in at a¹ is the same as in passing out at c, the
tension between the two apertures (shown by the column in f, f) will be due to the
friction in passing through the small holes or apertures. If, however, the air at a¹
is heated, its volume will be proportionately increased, and hence less of it can
enter through a¹. If now, it be cooled to the normal temperature before it passes
out at c, a less volume will have to pass through c, in consequence of which, the
partial vacuum (suction) will act more on the space between the two apertures and
the column in ff will rise to show the change of tension, and thus will indicate the
exact temperature at a'.

page_text: Having now particularly described and ascertained the nature of our said inven-
tion and in what manner the same is to be performed, we declare that what we
claim is:
1. The herein-described method of determining the temperature, which consists
in passing a gas through a tube or chamber having two apertures, the gas entering
one aperture at the degree of temperature to be indicated and flowing through the
other aperture at a constant temperature, the changes in the tension of the
gas between the two apertures being the measure of the temperature to be
indicated.
2. The herein-described method of determining the temperature, which consists
in passing a gas through a tube or chamber having two apertures, the gas being
raised to the degree of temperature to be indicated prior to entering one of the
apertures, then reducing the gas to a normal degree before it flows through
the other aperture, the change in the tension of the said gas between the said
apertures being a measure of the temperature to be determined.
3. The herein-described means for determining temperature, consisting of a tube
having two apertures, means for passing a gas through the tube under pressure, the
gas entering one aperture at the degree of temperature to be determined, and
a reducing device to bring the gas to a normal temperature before flowing through
the other aperture, the change of tension of the gas between the two apertures being
a measure to determine the degree of temperature to be ascertained.
4. The herein-described means for determining temperature, consisting of a tube
having two apertures, means for passing a gas under pressure through the tube, the
gas being raised to the degree of temperature to be ascertained before entering one
aperture, a reducing device to bring the gas to a normal temperature before flowing
through the other aperture, and a register having connection with the tube to
indicate the change in tension between the said two apertures, and the degree of
temperature to be determined.
5. A pyrometer consisting of a chamber in which a gas is raised to the degree of
temperature to be ascertained, a tube having a portion projected into the said
chamber, and having two apertures, a reducing device applied to the other portion
of said tube to bring the gas to a normal temperature before leaving the tube, a
register having connection with the said tube to indicate the change in tension of
the gas between the said apertures, and means for passing a gas through said tube
under pressure, substantially as and for the purpose set forth.
6. A pyrometer consisting of a tube having two small apertures and adapted to
be connected at one end to a pressure or partial vacuum chamber, a gage to indicate
the tension of said chamber, the gas being raised to the degree of temperature to be
determined before entering one aperture, a cooling device to reduce the temperature
of the gas to a normal or certain degree before flowing through the other aperture,
and a register to indicate the change in tension of the gas between the said
apertures, substantially as described.
7. The herein-described pyrometer consisting of a chamber having an inlet at or
near one end, a tube having a portion inserted within the said chamber and having
two apertures, a cooling device applied to the other portion of the tube to reduce
the gas passing through the same to a normal temperature before leaving the said
tube through the outlet aperture, means for creating a tension on the gas in the
tube, and registers to indicate the primary tension of the gas and the differences in
tension between the said two apertures, substantially as described.
Dated this 15th day of August 1893.
JENSEN & SON,
77, Chancery Lane, London, W.C., Patent Agents.