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Mineral Insulated Thermocouples

Product Description

Mineral Insulated Thermocouples & Resistance Temperature Detectors comprise of a metal sheath in which the thermo-electric elements/RTD element with conductors are embedded in highly compressed magnesium Oxide (MgO) insulation, thus providing the elements complete protection against oxidation and corrosion.

Thermocouples are available in type K, J, T, E, R, S, W, W3 and W5, simplex or duplex, in sheath diameters from 1mm to 19.05mm and length from a few cm to 200 meters or more. The hot junction is TIG welded and could be grounded (element hot junction welded to sheath tip giving faster response) or ungrounded (element insulated from sheath), one of which can be used as per control system requirement.

FEATURES

  • High Integrity construction suited to arduous operating conditions
  • High Accuracy & Stability maintained throughout operating life
  • Fast Response & High Insulation Resistance
  • Sheath can be bent & retains its form after bending to suit particular installation
  • Excellent Shock & Vibration Resistance
  • RTD are available with Platinum element, R=100 ohms, temp.coeff.0.385 ohm/°C, simplex or duplex, in sheath diameter from 3mm to 8mm and in lengths from 10 cm to several meters as per order

 

General Specification

DesignsDesign no.1…5 & IT40 Sr.Response time6 Sec.(63.2%) for 6mm OD sheath
HeadProvided in design no.4 & IT40 Sr.Smallest bending radiusTwice the sheath diameter
Head materialCast aluminumMountingAdjustable compression fitting
Head type        StandardWith threaded cover & cable entry (3/4”ET/ 1/2”BSP)(In design no.4 & IT40 Sr.)1/8”BSP(M) upto 6mm OD sheath other sizes on request in design no.4 Flange/ Threaded in IT40 Sr.
Weatherproof

Flameproof

Standard with gasket & challan (IP65)
CMRS approved for group 1,IIA,IIB & II C, weatherproof to IP65
Extension  Cable
(in design no.2)
Compensating Cable with fibre glass/figre
glass/SS wire braided insulation for Thermocouple. Copper cable with
Teflon/Teflon/SS wire braided Insul. For RTD other types on request
Terminal block (in design no.3,4 & IT40)Ceramic with brass terminals & with provision for two mounting screws on 33mm PCD; terminal block is spring loaded in design no.3 & IT40Connector
(in design no.5)
Of glass filled thermoplastic with thermocouple grade contacts & ANSI colour coaded for thermocouple (Design No.5A); Of MS, circular threaded locking type with copper contacts, 3/6 pin for RTD,(Design no.5B)
SheathAISI316/304/321/347/310/ 446/inconel600/ Hastalloy X in 1,5,3,4,5,6,8,12,7,15,8 & 19.05mm dia for thermocouples; AISI 316 in 3.2, 4.8, 7 & 8mm dia for RTDs.
ElementSimplex/duplex: J/K/T/E/N/S/R for thermocouples: Pt100, 2/3 wire for RTD with copper leads (Const./Ni. optional).Thermowell
(in IT40 Sr.)
Refer drg. No. TC260(3) for selection of Design. General construction of sensor in this case will be as per drg.no.TC259(3) using insert as per design no.3 alongwith
head & extension using nipple/union.
Insulation resistance10 M Ohms at 500V DC, 100M Ohms on request.  

PROTECTION SHEATH

Sheath MaterialComposition
(Appx)
Application guidelines
Stainless
Steel 304
18-20% Cr, 8-11% Ni,
<2% Mn balance iron
Upto 900°C in oxidizing conditions. Has goods resistance to oxidation and corrosion.
Stainless
Steel 316
16-18% Cr, 10-14% Ni,
2-3% Mo, balance iron
For use upto 900°C in oxidizing conditions.  Has goods resistance to corrosion mild acid & pitting.
Heat resistance
steel SS 446
23-27% Cr, balance IronUpto 100°C in oxidizing conditions. Excellent resistance to corrosion in sulphurous atmosphere. For use in salt bath & molten metal.
Stainless
Steel 310
24-26% Cr, 19-22% Ni
<2% Mn. Balance iron
Upto 1100°. High resistance to nitrogenous atmosphere, deficient in oxygen. Suitable for carburizing, annealing, hardening furnaces & cyanide salt bath.
Inconel 60072%(Min) Ni,
14-17% Cr, balance iron
Upto 1150°C under oxidizing conditions must not be placed in sulphurous atmosphere above 550°C. Suitable for carburizing, annealing & hardening furnace, cyanide salt bath etc.
Pt.6% Rh6% Rhodium and balance platinumFor R/S type thermocouples, maximum temperature 1650°C, for use in inert oxidizing environment.
TantalumTantalumFor R/S/W/W3/W5 thermocouples, maximum temperature 2200°C, for use in insert vacuum environment.

 

LIMITS OF ERROR FOR THERMOCOUPLESLIMITS OF ERROR FOR RTD Pt 100 
Element

Type

Temp.
Range °C

StandardSpecial

Temp. °C

Class ‘B’
±°C  ± Ω

Class ‘A’
±°C  ± Ω

 
Fe/Const.

J

0…700

±2.2°C/0.75%±1.1°C/0.4%

0

0.3

0.12

0.15

0.06

NiCr/Ni(Cr/Al0

K

0…1200

±2.2°C/0.75%±1.1°C/0.4%

100

0.8

0.30

0.35

0.13

Cu/Const.

T

0…..350

±1.0°C/0.75%±0.5°C/0.4%

200

1.3

0.48

0.55

0.20

Cr/Const.

E

0….900

±1.7°C/0.50%±1.1°C/0.4%

300

1.8

0.64

0.75

0.27

Nicrosil/Nisil

N

0….1280

±2.5°C/0.75%±1.5°C/0.4%

400

2.3

0.79

0.95

0.33

Pt10%Rh/Pt

S

0…..1600

±1.2°C/0.25%

-

500

2.8

0.93

1.15

0.38

Pt13%Rh/Pt

R

0….1600

±1.2°C/0.25%

APPLICATIONS

They are used in industries, power plants, and metal melting furnaces, salt baths, industrial process control, laboratories and numerous other applications as

  • Salt Bath : Neutral/ Cyanide/ Borax/ HSS/ Chloride/ Other
  • Molten Metal : Zinc/ Magnesium/ Aluminium/ Copper/ Brass/ Ferrous Alloys/ Other
  • Process Furnaces : Glass melting/ Cracking/ Roasting/ Blast/ Calcining/ Hydrogenising/ High Pressure Stoves (specify process material)
  • Ovens & Furnace with : Reducing/ Oxidising/ Sulphurous/ Carbonising gaseous atmosphere (Specify gas details)

Plating : Galvanising/ Tinning