THERMOCOUPLE TYPES:
 Given below is general description of
 commonly used thermocouples.

 IEC 584-1, PART1: S:
 This thermocouples can be used in
 oxidising or inert  atmosphere at
 temperatures described above.
 Recrystallised Alumina beads and
 protective sheaths are generally used.
 However, for lower temperatures upto
 1100 Deg C metal sheaths with porcelain
 beads can be used.
 Please note that continuous use at
 elevated temperature may cause fusing
 of Rhodium in pure Platinum causing
 reduction in output emf.

 IEC 584-1, PART2: R:
 This thermocouples can be used in
 applications similar to S type
 thermocouples.
 zhe advantage being slightly higher output
 at same temperature and better stability.
 This type is preferred over S type
 thermocouples.

 IEC 584-1, PART3: J:
 This thermocouples are commonly known
 as iron/constantant thermocouples and can
 be used in reducing or inert atmosphere at
 temperatures described above.
 Restrict use in oxidizing atmosphere to
 temperatures up to 400 deg C, otherwise
 degradation will be rapid. Avoid using for
 application where condensation temp is
 often reached otherwise Fe {+leg} will rust
 rapidly.

 IEC 584-1, PART4: K:
 This is most commonly used thermocouple ind is are
 commonly known as chromel/Alumel thermocouple

 These are designed primarily for use in Oxidising
 atmosphere at temperatures described above.

 Great care should be taken when using for any other
 atmosphere. These thermocouple will get oxidised
 when used continuously at temp above 1000 Deg C
 and cause drift.

 For temp range from 250 to 600 Deg C stability is
 suspect. Other base metal thermocouples are better
 bet at  this temp range.

 Cyclic
 temperature changes can cause error of several
 degrees at these temperatures.

 IEC 584-1, PART5: T:
 This is commonly used in laboratory applications
 where sub zero temperatures are often maintained.
 Repeatability at -200 + 200 Deg C is excellent.
 However at temp above this Copper arm rapidly
 oxidizes causing drift. Note that the negative arm of
 T and J type are not same and are not
 interchangeable.

 IEC 584-1, PART6: E and IEC 584-1, PART7: B
 These thermocouples are not in much use presently.
 E type is more stable in -250 + 200 Deg Range than
 K type and can be preferred over K in this range.
 Type B thermocouple can be used at temperature
 upto 1600 Deg c. Interesting point is that in this type
 cold junction compensation is not normally required
 as emf change from 0 to 50 is negligible.
 

STYLES OF THERMOCOUPLE ASSEMBLIES

 Hand held thermocouples are suitable for liquid, semi
 solid, leaf type for surface. Available in J and K type
 MI element with SS Sheath and Ebonite handle with
 PVC extension cable Suitable for Temp up to
 1100 Deg C.

 
 Suitable for moving surfaces such as calender rolls or
 motor shafts upto 225 Deg C and 200 MPM speeds.
 Available with spring loaded detection head extension
 leads and mounting brackets. Available in J and K
 type element.
 

 
 Heavy duty metal sheathed industrial thermocouples
 are suitable for most arduous industrial environment
 suchas furnaces, kilns, ovens Zinc Baths etc.
 Available in J, K, R & S type element with variety of
 sheaths such as SS 316, Inconell 600, and SS 310.

 
 High temperature ceramic sheathed thermocouples
 are suitable for temperatures upto 1600 Deg C
 Available in K, R & S type element with variety of
 sheaths such as SS SS 310, Porcelain, Ceramic and
 Recrystallised Alumina.

 
 Mineral insulated metal sheathed thermocouples are
 suitable for spaces which are difficult to reach.
 Available in J and K type element with variety of
 sheaths such as SS 316, Inconell 600, and SS 310.
 

 L shape thermocouples are suitable for molten metal
 baths. Hot are is manufactured from solid barstock
 for better life. Available in K type element with
 variety of sheaths such as Inconell 600, and SS 446.