US 1140701 A
Description (OCR text may contain errors)
A. F. MITCHELL. PROTECTING HOOD FOR THERMO-COUPLES.
APPLICATION FILED JUNE 23. I9I4.
Patented May 25, 1915.
.r IIIIIIII!IIIIIIII Z Z I. VENTOR r. MITCHELL, or nomnsrmn, PENNSYLVANIA.
PROTECTING-HOOD FOB THERIMO-GO'III'I'LES.
Specification of Letters Patent.
Patented May 25, 1915.
i Application filed June 23,1914. Serial No.- 846,716.
and while not restricted to such use more particularly relates to the construction of the hot end of thermo-couples forming part of electric pyrometers, used in determining the temperature of armor plates and similar metal bodies while such plates are being heated within a furnace.
Heretofore it has been the practice to in case the hot end of the thermo-couple within a cover made of iron', quartz, porcelain or similar heat resisting material, the covering being employed to prevent oxidation of the is brought iii-contact with the article whose.
thermo-couple and the thermo-couple, of course, being connected by suitably insulated wires to the galvanometer forming part of the pyrometer. It has also been the practice heretofore to use the apparatus by placing the naked or uncovered hot end of the thermo-couple in contact with the plate or other article, of which the tem erature is to be determined, the cold end 0 the thermocouple b connected by suitably insulated wires to the galvanometer forming part of When used in this manner, the hot end of the thermo-couple is subj ect to the heating influence of the gases or' products of combustion passing throu h the furnace, while the reading is being ta on and is also subjected to the cooling influence of the furnace bottom when applied to the under side of the plate or other metal body, both influences acting to make the readings inaccurate.
One object of my invention is to provide a thermo-couple having novel means whereby the hot end thereof is protected or insulated from the direct action of the highly heated gases of the furnace. 7 V.
Another object of my invention is to provide a thermo-couple having -novel means whereby the hot end of the thermo-couple temperature is to be measured while excluding it from the highlyheated atmosphere of the interior of the furnace in which the plates or other articles are situated.
Still further objects of my invention will become apparent hereinafter as the invention is more fully described and specifically pointed out in the appended claims.
My invention. consists in a protecting hood, which surrounds the thermo-couple and hasan open side which enables the thermo-couple being brought and held in di-' rect contact with the heated article, while its temperature is being determined and thereby excluding the thermo-couple from the action of the highly heated gases passing through the furnace.
Referring now to the drawings forming part of this specification, Figure 1 is a longitudinal sectional side elevation of a heating furnace for heating armor plates and similar large metal bodies. Fig. 2 is a longitudinal section showing on a larger scale, the construction of the protecting hood and the manner of applying the hood for use on the hot end of the thermo-couple in accordance with my invention. Fig. 3 is an inverted plan of the hood shown in Fig. Fig. 4 is an end elevation of the hood shown in Figs. 2 and'3.
'In the accompanying drawings, the numeral 2 indicates a heating furnace having an armor plate 3 mounted upon the supports 4 which are carried upon the movable bottom 5jof the furnace, the plate being supported in this manner to enable both sides to be simultaneously heated and obtain-a more uniform heating of the plates within the furnace.
The galvanometer 6 forming part of the electric pyrometer, is connected by lead wires 7 and 8 to the hot end 9 of the thermo-couple and the hot end of the thermo-couple is positioned within the enveloping protector or hood 10, forming a novel feature of this invention. The hot end 9 of the thermo-couple is conveniently bent to bring it into substantially the plane of'the side edges 11 of the open side of the protecting-hood 10.
The rear end of the protecting hood is v I noineter, the Wires forming the thermo-couple being of sufiicient. length to extend to the outside of the furnace and the wires con-' veniently extending through the hollow handle 12. The wires within the pipe may be v covered with a suitable insulation as is insulating material. I mineral wool are other-insulating materials shown.
The interior of the hood 10 which is inclosed upon all but one of its sides is preferably filled with a suitable insulating ma-- terial 13 forming a lining for the hood and assisting in maintaining the hot end of the thermo-couple in position within the protecting hood. Asbestos preferably is used as the Asbestos cement and by excluding such atmosphere from contact with the hot end of the thermo-couple, and in this way' the temperature readings are rendered much more accurate than has here;
tofore been possible with a paratus in which ing an open side enabling the thermo-couple to contact directly with the surfaces of which the wires extend, forms a convenientwheated articles.
means for positioning the hot end of the thermo-couple in the desiredlocation on the heated article within the furnace, it being inserted within the furnace through suitable openings provided for that purpose in the side walls and in the doors or end walls of the furnace.
In placing the hot end of the-thermo-couple in position the side edges 11.of the hood 10 come in contact with the surface of the plate, the temperature of which is being measured, and in this way prevent the highly heated gases in the furnace from coming into contact with the thermo-couple so that the heating action of the surface of the plate on the hot end of the thermo-couple alone determines the registered temperature and inaccuracies heretofore present, due to the action of the gases, which are at a higher temperature than the heated metal, are prevented and avoided. The hot end 9 and its surrounding hood 10 are held in direct contact with the surface of the plate 3 for the necessary time interval and the temperature of the hot end of the thermo-couple, which will be the same as that of the temperature of the plate in contact therewith, is transmitted through the lead wires 7 and 8 to the galvanometer and The advantages of my inventionwill be apparent to those skilled in the a-rtf" The use of my protecting hood prevents the temperatures taken being influenced by the highly heated atmosphere of the furnace,
the temperature indicated on. the dial of the galvahometer.
2. In an electric pyrometera thermo-couple having lead wires and a hood encircling the hot end of the thermo-couple, said hood having an open side enabling the thermo-couple to contact directly with the surfaces of the heated articles and an insulatin medium within the hollow protecting hood arranged to engage .with and hold the hot end of the thermo-couple in position within the protecting hood.
8. In an electric pyrometer a thermo-couple having lead wires and a hood encircling the hot end of the thermo-couple, said hood hav ing an .open side enabling the thermo couple to contact directly with the surfaces of heated articles and a handle secured to the protecting hood by which the hot end of the thermo-couple is manipulated.
4. In an electric pyrometer a thermo:couple having lead wires and a hood encircling the hot end of the thermo-couple, said hood having an open side enabling the thermo-couple to contact directly with the surfaces ofheated articles and a hollow handle secured to the protectinghood by which the hot end of the thermo-couple is manipulated, the leadiwires from the hot end of the couple extending through said hollow handle.
In testimony whereof, I have hereunto