US1849832A - Thermocouple - Google Patents

Thermocouple Download PDF

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Publication number
US1849832A
US1849832A US185324A US18532427A US1849832A US 1849832 A US1849832 A US 1849832A US 185324 A US185324 A US 185324A US 18532427 A US18532427 A US 18532427A US 1849832 A US1849832 A US 1849832A
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United States
Prior art keywords
thermocouple
sheath
tungsten
temperature
couple
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
Application number
US185324A
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English (en)
Inventor
Herzog Eugene
Harold L Watson
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General Electric Co
Original Assignee
General Electric Co
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Filing date
Publication date
Application filed by General Electric Co filed Critical General Electric Co
Priority to US185324A priority Critical patent/US1849832A/en
Priority to FR652647D priority patent/FR652647A/fr
Application granted granted Critical
Publication of US1849832A publication Critical patent/US1849832A/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01K—MEASURING TEMPERATURE; MEASURING QUANTITY OF HEAT; THERMALLY-SENSITIVE ELEMENTS NOT OTHERWISE PROVIDED FOR
    • G01K7/00—Measuring temperature based on the use of electric or magnetic elements directly sensitive to heat ; Power supply therefor, e.g. using thermoelectric elements
    • G01K7/02—Measuring temperature based on the use of electric or magnetic elements directly sensitive to heat ; Power supply therefor, e.g. using thermoelectric elements using thermoelectric elements, e.g. thermocouples
    • G01K7/04—Measuring temperature based on the use of electric or magnetic elements directly sensitive to heat ; Power supply therefor, e.g. using thermoelectric elements using thermoelectric elements, e.g. thermocouples the object to be measured not forming one of the thermoelectric materials
    • G01K7/06—Measuring temperature based on the use of electric or magnetic elements directly sensitive to heat ; Power supply therefor, e.g. using thermoelectric elements using thermoelectric elements, e.g. thermocouples the object to be measured not forming one of the thermoelectric materials the thermoelectric materials being arranged one within the other with the junction at one end exposed to the object, e.g. sheathed type

Definitions

  • the present invention relates to thermof couples, and comprises particularly thermocouples adapted accurately. to measure very high temperatures for prolongedgperiods of 5 time.
  • thermoelectric couple comprising tungsten andgraphite has thermoelectric and other physical properties Heretofore in the use of high temperaturev 20 peculiarly adapted for the determination of such high temperatures.
  • Thermocouples em-Y bodying the invention have proved to be adapted for continuously indicating and ac-Av curately measuring high temperatures be- 2 ⁇ 5 tween about 1000 to 2300o C. for prolonged periods of time.
  • One of the novel features Aof our invention comprises the combination with such a couple of means for protecting the couple from the effect of deleterious gases.
  • Fig. .l 1s a vertical cross-section of our improved form of thermocouple
  • Fig. 2 is a cross-sectional view taken on the line 2-2 of Fig: 1,
  • Fig.- 4 1s a curve whlch shows the voltage/ differ-J ence between the elements of the a temperature range.
  • thermocouple consisting of graphite and tungsten members which are given -a suitable heat treatment prior to assembly
  • thermocouple in order to provide a thermocouple the elements of which will be stabilized or in other words will have substantially constant electrical characteristics.
  • the heattreatment comprises heating the tungsten member, for
  • the heating and aging of the tungsten ⁇ produce a' structure having substantially constantelectrical characteristics. It is probable that this process results in the production of large tungsten crystals, thereby preventing a slow crystal growth of the tungsten member when subjected to heat which would cause variations-in the'electrical 'characteristics of the tungsten and, therefore, in readings obtained on an indicating device connected to the thermocouple.
  • the 'graph- -ite member is heated and agedin the same manner and at the same temperature asthe tungsten, the heating andagin'g ofthe graphite preventing substantially anyA subsequent' graphitization of carbon in the Agraphite member.
  • thermocouple when assembled,'is protected-by means of a'layer of suitable'carbon, such as charcoal, which'sur'rounds that. part of the couple exposed to high temperatures.
  • Ajportion ofthe charcoal combines at high v the lowerend of the graphite tube 3 andprovides, with rod 1, the hot junction of the thermocouple. 1 A
  • thermocouple remote from the hot junctioniscooled andmaintained at a desired temperature by means of a'water jacket consisting of'an inner metallic member 5 in contact with, the graphite tube and an outer metallic member 6.
  • the lower and tion the hot junction of thexthermocouple as y to accommodate rod.1, engages and closes upper ends of the jacket are closed byv plugs 7 and 8, respectively.
  • Water is supplied to the jacket through a pipe 9, the kougl'tlet being indicated at 10 (see Fig. 2).
  • verticalpr longitudinal partitions 11 and 12 are inserted between members 5 and 6 at opposite sides of rthe water jacket.
  • a tapered metal cap 13 is mounted on the upper end of the water jacket and is provided with a closure member or plug 14 .of conducting material mounted in an insulating bushing 15.
  • the plug 14 is provided at its lower end with screw threads adapted to engage a conducting rod 16.
  • This rod is provided with an adjustable plate 17I and iswelded at at its lower end to the upper end of the tungsten rod 1, as indicated at 18.
  • An insulating bushing 19 is mounted withinthe tube 5 to surround the welded joint between the tungsten member and the rod 16 and carries at its upper end an l insulating washer 19.
  • a spring 20 bears against the washer 19 and plate 17 and serves to maintain the graphite plug 4 in good electrical contact with the graphite sleeve 3,- and the tungsten rod -l'in good contact with plug 4.
  • the sheathis provided with a screw threaded ring 22 adapted to engage a second ring 23 mounted on an annular member24 secured to the lowerv end of the water jacket. Movement of ring 23 adjusts the position of the sheath 21 with respect to the thermocouple.
  • the sheath is provided with pins 25 movable in openings in the member 24, and is substantially filled with-suitable carbon, such as finely divided charcoal, as indicated at 2 6, which completely surrounds tlie lower portion of the thermocouple. If' desired, a graphite cap 29 may be lapplied at the lower end of the thermocouple to prevent the couple from stickingr to the sheath 21.
  • thermocouple Electrical connections may be made from the thermocouple to any suitable indicating device by means of a metal screw threaded binding post 27 'electrically connected to the vgra'phiteelement of the thermocouple through the water jacket, and by means of a screw threaded member 28 provided in plug 14.
  • thermocouple When the lower end of the thermocouple is placed in a furnace,l the temperature of which is to be measured, the heat fromthe furnace'causes-a portionof the vcharcoal to unite withwhatever oxygen may be present in the sheath, and vform carbon monoxide.
  • This gas 'forms alayercompletely surrounding the lower ⁇ lportion of the thermocouple, and since ⁇ the gas thus formed is inactive with respect to the elements of the thermocouple, it eii'ectively prevents any deleterious action on the 'thermocouple'dueto the high temperaslowly tures employed. ⁇
  • the charcoal may be renewed from time to time asfound necessary.
  • Sheath 21 may be made of various materials and its composition depends upon the circumstances under which it is intended to employ the thermocouple. In a gaseous oxidizing flame, it will beifound advantageous to employ a carborundum sheath, while if the temperature of molten iron is to be measured by immersion, thisv sheath will usually be composed of graphite bonded with clay.
  • an inert or inactive gas may be producedfby'dropping wood alcohol into the hot zone.
  • the particular gas employed, however, will, of course, depend upon the temperatures to be measured.
  • the ring 23 is provided with a supply pipe 30 which may be connected to a suitable source of gas supply, such as an ordinary commercial tank containing, for example, hydrogen.
  • a suitable source of gas supply such as an ordinary commercial tank containing, for example, hydrogen.
  • a small opening 31 is made in the lower end of the graphite member 3.
  • the heated gas enters opening 31, passes upwardly through members 3 and 19 and-then through a small openingV 32 in the insulator-.15 and out into the atmosphere.
  • valve 34 having a valve 34 is provided inthe ring 23. This arrangement allows a large volume of gas to be passed through the sheath, thereby effectively removing any accumulated air. Valve 34 is then-closed, and a quantity of gas,
  • thermocouple consisting of tungsten and graphite L-members and constructed in the manner above disclosed is particularly advantageous. since it will give a relatively high and substantially constant electromotive force for any given temperature and will operate at temperatures up to 2300 C., and even higher temperatures, depending on the conditions of use.
  • thermocouple consisting of the above elements has a further advantage due to the lowl temperature at which reversal of its electromotive force takes place. In the. operation of thermocouples, there is a tempera.-
  • thermocouple ture at whichthe electromotive force passes through zero and reverses. This reversal takes place 'with many couplesaat relatively high or extremely low temperatures. With the present type of thermocouple, this reversal takes place at about 100 C.,'so that the couple is not aected by this action throughout any portion of its operating range.
  • thermocouple consisting of arcarbon member and a tungstenv member
  • thermocouple' which -consist of tungsten and carbon, which comprises aging the elements prior to assembly at a temperature of about 2000 C. to thereby produce substantially constant electrical characteristics in said elements.

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  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Investigating Or Analyzing Materials Using Thermal Means (AREA)
US185324A 1927-04-20 1927-04-20 Thermocouple Expired - Lifetime US1849832A (en)

Priority Applications (2)

Application Number Priority Date Filing Date Title
US185324A US1849832A (en) 1927-04-20 1927-04-20 Thermocouple
FR652647D FR652647A (fr) 1927-04-20 1928-04-13 Perfectionnements apportés aux thermocouples, notamment à ceux qui sont destinés à la mesure des hautes températures

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
US185324A US1849832A (en) 1927-04-20 1927-04-20 Thermocouple

Publications (1)

Publication Number Publication Date
US1849832A true US1849832A (en) 1932-03-15

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Application Number Title Priority Date Filing Date
US185324A Expired - Lifetime US1849832A (en) 1927-04-20 1927-04-20 Thermocouple

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US (1) US1849832A (fr)
FR (1) FR652647A (fr)

Cited By (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2833844A (en) * 1954-07-20 1958-05-06 Land Pyrometers Ltd Measurement of temperatures
US2906800A (en) * 1956-12-26 1959-09-29 United States Steel Corp Self-ventilating thermocouple well
US2930827A (en) * 1953-07-23 1960-03-29 Gen Motors Corp Thermocouple
US2934941A (en) * 1955-12-29 1960-05-03 Honeywell Regulator Co Heat treating constituent measuring means
US2975225A (en) * 1957-05-24 1961-03-14 Curtiss Wright Corp High temperature probe
US3060251A (en) * 1960-09-30 1962-10-23 Union Carbide Corp Head for thermoelectric device
US3097973A (en) * 1960-05-23 1963-07-16 Emil S Wieszeck Protectively contained sensing apparatus
US3301715A (en) * 1965-09-23 1967-01-31 John E Gerrard Thermocouple for multiple burner combustion control
US3451860A (en) * 1965-12-17 1969-06-24 Gen Motors Corp Thermocouple with reducing atmosphere producing sheath
EP0644410A1 (fr) * 1993-09-21 1995-03-22 Centre De Recherche En Machines Thermiques C.R.M.T. Thermocouple-capteur et son procédé de fabrication

Cited By (11)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2930827A (en) * 1953-07-23 1960-03-29 Gen Motors Corp Thermocouple
US2833844A (en) * 1954-07-20 1958-05-06 Land Pyrometers Ltd Measurement of temperatures
US2934941A (en) * 1955-12-29 1960-05-03 Honeywell Regulator Co Heat treating constituent measuring means
US2906800A (en) * 1956-12-26 1959-09-29 United States Steel Corp Self-ventilating thermocouple well
US2975225A (en) * 1957-05-24 1961-03-14 Curtiss Wright Corp High temperature probe
US3097973A (en) * 1960-05-23 1963-07-16 Emil S Wieszeck Protectively contained sensing apparatus
US3060251A (en) * 1960-09-30 1962-10-23 Union Carbide Corp Head for thermoelectric device
US3301715A (en) * 1965-09-23 1967-01-31 John E Gerrard Thermocouple for multiple burner combustion control
US3451860A (en) * 1965-12-17 1969-06-24 Gen Motors Corp Thermocouple with reducing atmosphere producing sheath
EP0644410A1 (fr) * 1993-09-21 1995-03-22 Centre De Recherche En Machines Thermiques C.R.M.T. Thermocouple-capteur et son procédé de fabrication
FR2710409A1 (fr) * 1993-09-21 1995-03-31 Crmt Thermocouple-capteur et son procédé de fabrication.

Also Published As

Publication number Publication date
FR652647A (fr) 1929-03-11

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