{"id":6142,"date":"2023-02-09T07:51:53","date_gmt":"2023-02-09T06:51:53","guid":{"rendered":"https:\/\/mesurex-sensors.com\/uncategorized\/bien-choisir-son-thermocouple\/"},"modified":"2026-05-03T13:29:30","modified_gmt":"2026-05-03T11:29:30","slug":"choosing-the-right-thermocouple","status":"publish","type":"post","link":"https:\/\/mesurex-sensors.com\/en\/actualites\/bien-choisir-son-thermocouple\/","title":{"rendered":"CHOOSING THE RIGHT THERMOCOUPLE"},"content":{"rendered":"

\"\"
\nThere are many different types of thermocouples, depending on the metal alloys used, but the most common are 8 types are mainly used in our workshops<\/strong> (T, K, N, J, E, R, S, B). Find out which one is right for you.<\/p>\n\n\n\n\n\n\n\n\n\n\n\n
TYPE<\/strong><\/td>\nAlloys used<\/strong><\/td>\nMounted under ceramic beads <\/strong>
\n(rigid sheath)<\/strong><\/td>\n		In jacketed version with outer sheath and MgO <\/strong>
\n(flexible sheath)<\/strong><\/td>\n<\/tr>\n
T<\/strong><\/span><\/td>\nCopper (+)<\/span>
\nConstantan (-)<\/span><\/td>\n		Use: in both oxidizing and reducing atmospheres<\/span>
\nIts low-temperature stability means greater precision.<\/span>
\nRecommended for very low temperatures (cryogenics).<\/span>
\nOperating temperature:<\/span>
\n-200\u00b0C to 350\u00b0C<\/span><\/td>\n		Usage: between -40 and 350\u00b0C\u00a0<\/span>
\nHighly stable for low-temperature measurement applications and cryogenics.<\/span>
\nFor use below 0\u00b0C, check the compatibility of the outer sheath.<\/span><\/td>\n<\/tr>\n
K<\/strong><\/span><\/td>\nChromel (+)<\/span>
\nAlumel (-)<\/span><\/td>\n		Use: reliable and precise, it is used extensively for temperatures up to 1200\u00b0C.<\/span>
\nIn a reducing atmosphere (presence of carbon dioxide): protect this thermocouple with a metal or ceramic\/alumina tube. In an oxidizing atmosphere (e.g. electric furnace, presence of oxygen), protection is not necessary.<\/span>
\nGenerally longer service life than type J, which will oxidize more quickly (especially at high temperatures).<\/span>
\nOperating temperature:<\/span>
\n-40\u00b0C to 1200\u00b0C<\/span><\/td>\n		Usage: between -40 and 1200\u00b0C .<\/span>
\nBetween 315\u00b0C and 600\u00b0C, MESUREX recommends type J or N, as instability in the structure of the internal alloys will cause a drift of around +2\u00b0C after a few hours' use.<\/span>
\nExcellent solution for nuclear environments.<\/span><\/td>\n<\/tr>\n
N<\/strong><\/span><\/td>\nNicrosil (+)<\/span>
\nNisil (-)<\/span><\/td>\n		Use: mainly at high temperatures up to 1250\u00b0C. Better resistance to oxidation at high temperatures and longer service life in applications where sulfur is present. <\/span>
\nNo premature ageing problems (like type K).<\/span>
\nOperating temperature: -40\u00b0C to 1250\u00b0C<\/span><\/td>\n		Usage: between 0 and 1250\u00b0C.<\/span>
\nVery stable over time with no drift at high temperatures.<\/span>
\nHigh-temperature applications require Pyrosil, Alloy TD or Nicrobel sheathing. <\/span>
\nType N is particularly recommended for nuclear applications.<\/span><\/td>\n<\/tr>\n
J<\/strong><\/td>\nIron (+)
\nConstantan (-)<\/td>\n		Usage: protected or unprotected, subject to absence of oxygen. Protection will prevent oxidation and extend service life. As the positive conductor is iron, it oxidizes rapidly above 540\u00b0C. The use of a simple conductor with a larger diameter will increase its service life.
\nTemperature range: -40\u00b0C to 750\u00b0C.<\/td>\n		Usage: between -40 and 750\u00b0C .
\nGreater stability between 0 and 538\u00b0C than types E and K (drift associated with ageing).
\nVery economical thermocouple, mainly with stainless steel sheath.<\/td>\n<\/tr>\n
E<\/strong><\/span><\/td>\nChromel (+)<\/span>
\nConstantan (-)<\/span><\/td>\n		Use: less commonly used, but nevertheless a good choice for temperatures up to 900\u00b0C.<\/span>
\nRecommended for vacuum, inert gas, moderately oxidizing or reducing applications.<\/span>
\nFor cryogenic applications, it is not subject to corrosion.<\/span>
\nType E generates a higher voltage signal than all other thermocouple types.<\/span>
\nOperating temperature: -40\u00b0C to 800\u00b0C<\/span><\/td>\n		Usage: between 0 and 900\u00b0C.<\/span>
\nBetween 315 and 600\u00b0C, however, MESUREX recommends type J or N (drift associated with ageing).<\/span>
\n.<\/td>\n<\/tr>\n
R<\/strong><\/span><\/td>\nPt 13% Rh (+)<\/span>
\nPt (-)<\/span><\/td>\n		Thermocouples for high temperatures.
\nOperating temperature: Type S or R from 0 to 1600\u00b0C
\nType B from 600 to 1700\u00b0C.
\nThese thermocouples are easily contaminated, so they should not be used in a reducing atmosphere.
\nThese noble metal thermocouples should preferably be protected by a ceramic tube (alumina) or by an outer metal tube below 1200\u00b0C.<\/td>\n		Because of the high operating temperature of these thermocouples, the external metal sheath will often be an obstacle to their use.
\nProducts offered with Inconel or platinum sheaths (very costly), mainly for type S.
\nOperating temperature:
\nType S 0 to 1250\u00b0C.<\/td>\n<\/tr>\n
S<\/strong><\/span><\/td>\nPt 10% Rh (+)<\/span>
\nPt (-)<\/span><\/td>\n<\/tr>\n
B<\/strong><\/span><\/td>\nPt 30% Rh (+)<\/span>
\nPt 6% Rh (-)<\/span><\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

Precision class: what does the standard say?<\/h2>\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n
TYPE<\/strong><\/td>\nTolerance value<\/strong><\/td>\n<\/tr>\n
Class 1<\/strong><\/td>\nClass 2<\/strong><\/td>\nClass 3<\/strong><\/td>\n<\/tr>\n
T<\/strong><\/span><\/td>\n\u00b10.5 or 0.004\u00d7T<\/strong><\/span><\/td>\n\u00b11 or 0.0075\u00d7T<\/strong><\/span><\/td>\n\u00b11 or 0.015\u00d7T<\/strong><\/span><\/td>\n<\/tr>\n
-40...350\u00b0C<\/strong><\/span><\/td>\n-40...350\u00b0C<\/strong><\/span><\/td>\n-200...40\u00b0C<\/strong><\/span><\/td>\n<\/tr>\n
E<\/strong><\/span><\/td>\n\u00b11.5 or 0.004\u00d7T<\/strong><\/span><\/td>\n\u00b12.5 or 0.075\u00d7T<\/strong><\/span><\/td>\n\u00b12.5 or 0.015\u00d7T<\/strong><\/span><\/td>\n<\/tr>\n
-40...800\u00b0C<\/strong><\/span><\/td>\n-40...900\u00b0C<\/strong><\/span><\/td>\n-200...40\u00b0C<\/strong><\/span><\/td>\n<\/tr>\n
J<\/strong><\/td>\n\u00b11.5 or 0.004\u00d7T<\/strong><\/span><\/td>\n\u00b12.5 or 0.075\u00d7T<\/strong><\/span><\/td>\n\u00b12.5 or 0.015\u00d7T<\/strong><\/span><\/td>\n<\/tr>\n
-40...750\u00b0C<\/strong><\/span><\/td>\n-40...750\u00b0C<\/strong><\/span><\/td>\n\u00a0<\/strong><\/td>\n<\/tr>\n
K<\/strong><\/span><\/td>\n\u00b11.5 or 0.004\u00d7T<\/strong><\/span><\/td>\n\u00b12.5 or 0.075\u00d7T<\/strong><\/span><\/td>\n\u00b12.5 or 0.015\u00d7T<\/strong><\/span><\/td>\n<\/tr>\n
-40...1000\u00b0C<\/strong><\/span><\/td>\n-40...1200\u00b0C<\/strong><\/span><\/td>\n-200...40\u00b0C<\/strong><\/span><\/td>\n<\/tr>\n
N<\/strong><\/span><\/td>\n\u00b11.5 or 0.004\u00d7T<\/strong><\/span><\/td>\n\u00b12.5 or 0.075\u00d7T<\/strong><\/span><\/td>\n\u00b12.5 or 0.015\u00d7T<\/strong><\/span><\/td>\n<\/tr>\n
-40...1000\u00b0C<\/strong><\/span><\/td>\n-40...1200\u00b0C<\/strong><\/span><\/td>\n-200...40\u00b0C<\/strong><\/span><\/td>\n<\/tr>\n
R & S<\/strong><\/span><\/td>\n\u00b11 for T<1100\u00b0C<\/strong><\/span>
\n1+0.003\u00d7(T-1100) for T>1100\u00b0C<\/span><\/td>\n		\u00b11.5 or 0.0025\u00d7T<\/strong><\/span><\/td>\n\u00a0<\/strong><\/td>\n<\/tr>\n
0...1600\u00b0C<\/strong><\/span><\/td>\n0...1600\u00b0C<\/strong><\/span><\/td>\n\u00a0<\/strong><\/td>\n<\/tr>\n
B<\/strong><\/span><\/td>\n\u00a0<\/strong><\/td>\n\u00b11.5 or 0.0025\u00d7T<\/strong><\/span><\/td>\n\u00b14 or 0.005\u00d7T<\/strong><\/span><\/td>\n<\/tr>\n
\u00a0<\/strong><\/span><\/td>\n600 to 1700\u00b0C<\/strong><\/span><\/td>\n600 to 1700\u00b0C<\/strong><\/span><\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

Temperature limits for sheaths and protective materials.
\nThermocouples come in 3 main forms:
\n-> Bare-wire version with rigid outer tube protection
\n-> Jacketed version: the thermocouple wires are positioned in a flexible metal tube filled with a mineral insulator (magnesia, aluminum oxide....).
\n-> Wired version: thermocouple wires are insulated with PVC, silicone, Teflon, glass silk or ceramic fiber.<\/p>\n

Flexible wired versions with insulation :<\/h2>\n
    \n
  • These versions are used to make single thermocouples or to make compensating or extension cables.
    \nThe cable used to build a wired sensor guarantees all the thermocouple's thermoelectric characteristics over the entire temperature range.<\/li>\n
  • Extension cable: used to connect the thermocouple to the measuring instrument; its conductors have the same thermoelectric characteristics and properties as their respective thermocouples.<\/li>\n
  • Compensating cable: used to connect the thermocouple to the measuring instrument; its conductors have different characteristics from those of the thermocouples to which they are connected, although they retain the same thermoelectric properties.<\/li>\n<\/ul>\n\n\n\n\n\n\n\n\n\n
    Temp.
    \nmax. \u00b0C<\/strong><\/td>\n    		INSULATION<\/strong><\/td>\nUse<\/strong><\/td>\n<\/td>\n<\/tr>\n
    -20...105<\/td>\nPVC<\/td>\nGood mechanical and electrical characteristics<\/td>\n<\/td>\n<\/tr>\n
    -40...200<\/td>\nSILICONE<\/td>\nExcellent flexibility even at low temperatures<\/td>\n<\/td>\n<\/tr>\n
    -200...250<\/td>\nTEFLON<\/td>\nChemical resistance and excellent mechanical properties<\/td>\n<\/td>\n<\/tr>\n
    -200...400<\/td>\nKAPTON<\/td>\nExcellent dielectric and chemical properties<\/td>\n<\/td>\n<\/tr>\n
    400<\/td>\nGLASS SILK<\/td>\nGood resistance to high temperatures - non-combustible but porous<\/td>\n<\/td>\n<\/tr>\n
    1200<\/td>\nCERAMIC FIBER<\/td>\nVery good resistance to high temperatures - non-combustible but porous<\/td>\n<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

    Flexible jacketed versions with mineral insulation :<\/h2>\n

    This version consists of a metal sheath containing conductors insulated from each other by highly pure, highly compressed metal oxides. This product offers many advantages: robustness, short reaction time, good insulation, high temperature.<\/p>\n\n\n\n\n\n\n\n\n\n
    Type<\/strong><\/td>\nTemp.
    \nmax. \u00b0C<\/strong><\/td>\n    		Application<\/strong><\/td>\n<\/td>\n<\/tr>\n
    304SS<\/td>\n800<\/td>\nGeneral-purpose stainless steel.
    \nGood corrosion resistance.<\/td>\n    		<\/td>\n<\/tr>\n
    316SS<\/td>\n1050<\/td>\nGeneral-purpose stainless steel.
    \nSuperior corrosion resistance.<\/td>\n    		<\/td>\n<\/tr>\n
    310SS<\/td>\n1050<\/td>\nSuperior corrosion resistance.
    \nHighly resistant to high temperatures.<\/td>\n    		<\/td>\n<\/tr>\n
    446SS<\/td>\n1100<\/td>\nUsed in sulfurous atmospheres.<\/td>\n<\/td>\n<\/tr>\n
    Inconel 600<\/td>\n1150<\/td>\nExcellent resistance to oxidation and high-temperature corrosion.<\/td>\n<\/td>\n<\/tr>\n
    Pyrosil D<\/td>\n1250<\/td>\nGreater resistance to oxidation than 310SS & INC 600.
    \nMore resistant to high temperatures than 310SS & INC 600.
    \nCoefficient of thermal elasticity compatible with nickel alloys (thermocouple type K and N)<\/td>\n    		<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

    For this type of product, a minimum external diameter must also be respected, depending on the temperature of use:<\/p>\n\n\n\n\n\n\n\n\n
    Type<\/strong><\/td>\n\u00d80.5<\/strong><\/td>\n\u00d81<\/strong><\/td>\n\u00d81.5<\/strong><\/td>\n\u00d82<\/strong><\/td>\n\u00d83<\/strong><\/td>\n\u00d84.5<\/strong><\/td>\n\u00d86<\/strong><\/td>\n\u00d88<\/strong><\/td>\n<\/tr>\n
    304SS<\/td>\n700\u00b0C<\/td>\n700\u00b0C<\/td>\n800\u00b0C<\/td>\n800\u00b0C<\/td>\n800\u00b0C<\/td>\n800\u00b0C<\/td>\n800\u00b0C<\/td>\n800\u00b0C<\/td>\n<\/tr>\n
    310SS<\/td>\n700\u00b0C<\/td>\n700\u00b0C<\/td>\n920\u00b0C<\/td>\n920\u00b0C<\/td>\n1050\u00b0C<\/td>\n1050\u00b0C<\/td>\n1050\u00b0C<\/td>\n1050\u00b0C<\/td>\n<\/tr>\n
    446SS<\/td>\n700\u00b0C<\/td>\n700\u00b0C<\/td>\n920\u00b0C<\/td>\n920\u00b0C<\/td>\n1070\u00b0C<\/td>\n1100\u00b0C<\/td>\n1100\u00b0C<\/td>\n1100\u00b0C<\/td>\n<\/tr>\n
    Inconel 600<\/td>\n700\u00b0C<\/td>\n700\u00b0C<\/td>\n920\u00b0C<\/td>\n920\u00b0C<\/td>\n1070\u00b0C<\/td>\n1150\u00b0C<\/td>\n1150\u00b0C<\/td>\n1150\u00b0C<\/td>\n<\/tr>\n
    <\/td>\n<\/td>\n<\/td>\n<\/td>\n<\/td>\n<\/td>\n<\/td>\n<\/td>\n<\/td>\n<\/td>\n<\/td>\n<\/td>\n<\/td>\n<\/td>\n<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

    Rigid versions with external protection tube :<\/h2>\n

    These versions are particularly suitable for very high temperatures. The thermocouple is mounted under a ceramic bead with one or two protection tubes. A DIN head is often used for the electrical connection.<\/p>\n\n\n\n\n\n\n\n\n\n\n\n\n\n
    Type<\/strong><\/td>\nTemp.
    \nmax. \u00b0C<\/strong><\/td>\n    		Application<\/strong><\/td>\n<\/tr>\n<\/thead>\n
    446 SS<\/td>\n1100<\/td>\nExcellent resistance in salt bath applications (heat treatment). Fairly resistant to aluminum electrolytic baths.<\/td>\n<\/tr>\n
    Cast iron<\/td>\n870<\/td>\nInexpensive material used in liquid aluminum. The tube has a relatively short life due to oxidation, but other materials also have their drawbacks in this application. Fragile metal.<\/td>\n<\/tr>\n
    HR-1600<\/td>\n1204<\/td>\nExceptional resistance to various forms of corrosive attack at high temperatures.<\/td>\n<\/tr>\n
    Inconel 6011<\/td>\n1260<\/td>\nHighly resistant to oxidation for processes with high to moderate oscillating temperatures. Resistant to sulfur compounds and carbon dioxides at moderate temperatures only.<\/td>\n<\/tr>\n
    Alumina (99%)1<\/td>\n1900<\/td>\nUsed in the glass and non-ferrous metal industries. Highly gas-tight, it provides excellent protection for noble metal thermocouples.<\/td>\n<\/tr>\n
    Hexoloy SA2<\/td>\n1650<\/td>\nIncinerator, liquid aluminum and non-ferrous metals, hydrofluoric and sulfuric acids, bauxite calcination.<\/td>\n<\/tr>\n
    Mullite<\/td>\n1700<\/td>\nUsed in the non-ferrous metals industry and in various industrial furnaces. Highly gas-tight, not recommended for noble metal thermocouples as it contains silica.<\/td>\n<\/tr>\n
    Syalon3<\/td>\n1150<\/td>\nA strong material, highly resistant to thermal shock. Widely used in the aluminum industry, especially for scuppers. Rather expensive material.<\/td>\n<\/tr>\n
    Silicon carbide<\/td>\n1650<\/td>\nExcellent thermal shock resistance. High thermal conductivity. A porous material which, combined with an internal ceramic tube, provides good protection for noble metal thermocouples.<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

     
    \nAmong the many temperature measurement sensors, the thermocouple<\/strong> is undoubtedly the most commonly used product, because it offers good precision while remaining economical<\/strong>.
    \nWith so many variations, shapes and protective tubes to choose from, it's not always easy to decide which products to use. Above all, you need to ask yourself the right questions:
    \nWhat is my operating temperature (thermocouples can measure temperatures from -200\u00b0C to +1700\u00b0C)?<\/span>
    \nWhat is the measurement environment? (liquid \/ solid \/ gaseous environment, chemically aggressive environment, extreme conditions...)<\/span><\/span>?<\/span>
    \nWhat is the desired level of precision?
    \nHow much space is available for these measurements?...
    \n<\/span>
    \n\"\"
    \nFICHE SYNTHESE: How to choose your thermocouple? Types, specifications, standards, recommendations...
    \nfile
    \nhttps:\/\/mesurex.fr\/wp-content\/uploads\/2023\/11\/MESUREX-Guide-de-selection-des-thermocouples_v2.pdf<\/p>","protected":false},"excerpt":{"rendered":"

    Il existe de nombreux types de thermocouples, en fonction des alliages de m\u00e9taux utilis\u00e9s, mais 8 types sont majoritairement utilis\u00e9s en nos ateliers (T, K, N, J, E, R, S, B). D\u00e9couvrez quel est le bon par rapport \u00e0 votre besoin. TYPE Alliages utilis\u00e9s En montage sous perle c\u00e9ramique (gaine rigide) En version chemis\u00e9e avec […]<\/p>\n","protected":false},"author":1,"featured_media":7041,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[37],"tags":[],"class_list":["post-6142","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-actualites"],"_links":{"self":[{"href":"https:\/\/mesurex-sensors.com\/en\/wp-json\/wp\/v2\/posts\/6142","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/mesurex-sensors.com\/en\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/mesurex-sensors.com\/en\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/mesurex-sensors.com\/en\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/mesurex-sensors.com\/en\/wp-json\/wp\/v2\/comments?post=6142"}],"version-history":[{"count":7,"href":"https:\/\/mesurex-sensors.com\/en\/wp-json\/wp\/v2\/posts\/6142\/revisions"}],"predecessor-version":[{"id":7040,"href":"https:\/\/mesurex-sensors.com\/en\/wp-json\/wp\/v2\/posts\/6142\/revisions\/7040"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/mesurex-sensors.com\/en\/wp-json\/wp\/v2\/media\/7041"}],"wp:attachment":[{"href":"https:\/\/mesurex-sensors.com\/en\/wp-json\/wp\/v2\/media?parent=6142"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/mesurex-sensors.com\/en\/wp-json\/wp\/v2\/categories?post=6142"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/mesurex-sensors.com\/en\/wp-json\/wp\/v2\/tags?post=6142"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}