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General Information

Home Thermocouple Wire General Information

General Information Wire | Marlin Manufacturing

Thermocouple Insulation, provides electrical insulation for thermocouple and thermocouple extension wire. If the insulation breaks down for any reason, the indicated temperature may be in error. When selecting insulation moisture, abrasion, flexing, chemical attack, temperature extremes and any other adverse environmental considerations must be evaluated. Insulations are rated for a maximum continuous use temperature and also a maximum single exposure temperature because after excessive temperatures have been encountered the insulation may become conductive or conductive residues may form even though the insulation remains physically intact. Also do not assumethe temperature rating as the temperature at the sensing junction of the thermocouple without evaluating the thermocouple system.

Fibrous Insulation, is either braided or wrapped on the conductors. In general, fibrous insulations are used for applications where extreme moisture and abrasion resistance requirements are not prevalent. Available at moderate cost for upper utilization temperatures of 900°F (482°C) for fiberglass, 1600°F (780°C) for high temperature silica fiber, and 2400°F (1315°C) for ceramic fiber.
Plastic Insulation, is used on comparatively lower temperature applications and provides good moisture and abrasion resistance. Available at low to moderate cost for typical upper utilization temperatures of 220°F (104°C) for PVC and 500°F (260°C) for teflon and silicon rubber.

WIRING ELECTRONIC INSTRUMENTS to conform to national and local codes does not address the “noise” problems of electronic instruments. Shielding of thermocouple and thermocouple extension wire may be necessary but not the only requirement of reducing noise. Ever since the introduction of electronics into instruments, noise generated by external relays, switches, motors, phase fired thyristors, etc., have caused problems that interfere with the instrument’s operation. Now that microprocessors are being increasingly incorporated into many more varied instruments, external sources that generate noise pulses that, in some cases, may render the instrument completely inoperative, have become crucial to instrument applications. While much can be done within the instrument to reduce its sensitivity to external noise, the solution in many cases can only be resolved by supressing the noise generation at its source.

Calibration Type Characteristics

  • Type T
  • Type J
  • Type E
  • Type K
  • Type N
  • Type B
  • Type S & R
  • Type C

Type T

(COPPER vs CONSTANTAN) is used for service in oxidizing, inert or reducing atmospheres or in vacuum. It is highly resistant to corrosion from atmospheric moisture and condensation and exhibits high stability at low temperatures; it is the only type with limits of error guaranteed for cryogenic temperatures.

Type J

(IRON vs CONSTANTAN) is used protected or unprotected in vacuum, oxidizing, inert or reducing atmospheres. Iron element oxidizes rapidly at temperatures exceeding 1000°F, and therefore heavier gauge wire is recommended for longer life at these temperatures.

Type E

(CHROMEL vs CONSTANTAN) may be used protected or unprotected in oxidizing, inert or dry reducing atmospheres, or for short periods of time under vacuum. Must be protected from sulfurous and marginally oxidizing atmospheres. Produces the highest EMF per degree of any standardized thermocouple.

Type K

(CHROMELTM vs ALUMELTM) is used protected or exposed in oxidizing, inert or dry reducing atmospheres. Exposure to vacuum limited to short time periods. Must be protected from sulfurous and marginally oxidizing atmospheres. Reliable and accurate at high temperatures. (Hoskins Mfg Co.™)

Type N

(NICROSIL vs NISIL) is used protected or exposed in oxidizing, inert or dry reducing atmospheres. Must be protected from sulfurous atmospheres. Very reliable and accurate at high temperatures.

Type B

(PLATINUM-30%RHODIUM vs PLATINUM-6%RHODIUM)

Type S & R

Type S (PLATINUM-10%RHODIUM vs PLATINUM)
Type R (PLATINUM-13%RHODIUM vs PLATINUM)

Platinum alloy thermocouples are all recommended for use in inert or oxidizing atmospheres, or for short periods of time in a vacuum. Easily contaminated, these elements must be protected from the effects of reducing atmospheres and contaminating vapors. Alumina protecting tubes are recommended for directly containing platinum element.

Type C

Type C^ (TUNGSTEN 5% RHENIUM vs TUNGSTEN 26% RHENIUM)
Tungsten alloy thermocouples are recommended for use in vacuum, high purity hydrogen, or high purity inert atmospheres. Very poor oxidation resistance. (^Not ANSI/ASTM symbol).

Supplementary Information

Thermocouple and Thermocouple Extension Wire Color Codes

ANSI/ASTM COLOR CODE FOR THERMOCOUPLE AND THERMOCOUPLE EXTENSION WIRE
ANSI/ASTM TYPEWIRE ALLOYSPOLARITYTHERMOCOUPLE WIRE COLORANSI/ASTMT/C EXTENSION WIRE COLOR
INDIVIDUALOVERALLTYPEINDIVIDUALOVERALL
TCOPPER
CONSTANTAN
+TPBLUEBROWNTXBLUEBLUE
-TNREDRED
JIRON
CONSTANTAN
+JPWHITEBROWNJXWHITEBLACK
-JNREDRED
ECHROMEL
CONSTANTAN
+EPPURPLEBROWNEXPURPLEPURPLE
-ENREDRED
KCHROMEL
ALUMEL
+KPYELLOWBROWNKXYELLOWYELLOW
-KNREDRED
NNICROSIL
NISIL
+NPORANGEBROWNNXORANGEORANGE
-NNREDRED
RPLATINUM 13%RHODIUM
PLATINUM
+RP––RXBLACKGREEN
-RN––RED
SPLATINUM 10%RHODIUM
PLATINUM
+SP––SXBLACKGREEN
-SN––RED
BPLATINUM 30%RHODIUM
PLATINUM 6% RHODIUM
+BP––BXGREYGREY
-BN––RED

Nominal Thermocouple Resistance

NOMINAL THERMOCOUPLE RESISTANCE Ohms per Double Foot @ 68°F (20°C)
Wire (GA)
B & S
Wire Size
DIA.
ANSI/ASTM TYPES
JKTESRB
60.1620.0140.0230.0120.0270.0070.0070.008
*70.1440.021––––––
80.1280.0220.0360.0190.0440.0100.0100.013
14
0.064
0.0890.1470.0740.1760.0440.0440.054
160.0500.1410.2320.1170.2770.0690.0690.086
180.0400.2290.3770.1900.4500.1120.1130.139
200.0320.3570.5880.2970.7020.1750.1780.218
240.0200.9051.4880.7451.7780.4490.4530.550
260.0151.4412.451.202.840.7010.7080.875
280.0122.2973.591.924.331.0621.0731.392
300.0103.656.022.947.191.7941.8132.213
360.00514.6624.0812.2228.807.1507.2268.897
(*) Double feet 7 GA Type J = 7 Ga Iron/8 Ga Constantan

Bare Thermocouple Wire

Ordering Information Bare Thermocouple Wire - Approx. Weight (ft/lb)
Wire
Ga
B & S
Wire
Size
DIA.
TYPE JTYPE K TYPE T TYPE E
Iron+ Constantan- Chromel+Alumel-Copper+Constantan- Chromel+Constantan-
JPJNKPKNTPTNEPEN
60.16214.212.6131312.612.61312.6
70.14418.0-------
80.12822.820.2212119.820.22120.2
140.06491.280.9838380.580.98380.9
160.050144127130130128127130127
180.040233207212212203207212207
200.032365324331331324324331324
240.020925821838838820821838821
260.01514781312134013401299131213401312
280.01223532089213021302062208921302089
300.01037363316337033703294331633703316
360.0051494013260135001350013250132601350013260

American Wire Gauge Sizes

American Wire Gauge (AWG)Size DIA.
Inches
7/0-
6/00.5800
5/00.5165
4/00.4600
3/00.4096
2/00.3648
1/00.3249
10.2893
20.2576
30.2294
40.2043
50.1819
60.1620
70.1443
80.1285
90.1144
100.1019
110.0907
120.0808
130.0720
140.0641
150.0571
160.0508
170.0453
180.0403
190.0359
200.0320
210.0285
220.0253
230.0226
240.0201
250.0179
260.0159
270.0142
280.0126
290.0113
300.0100
310.00893
320.00795
330.00708
340.00630
350.00561
360.00500
370.00445
380.00396
390.00353
400.00314
410.00280
420.00249
430.00222
440.00198
0.00176
460.00157
470.00140
480.00124
490.00111
500.00099

Thermocouple Wire Constructions

Constructions are arrangements of the conductor and insulation that suit the application. For instance, singles can be used to wire panels more easily than a jacketed construction. And duplex constructions can be more easily used in conduits. And twisted duplex constructions are more flexible than paralleled ones and counteract flux induced noises. Twisted and shielded constructions provide the best noise reduction.

CONSTRUCTIONS
CodeDescriptions
1Insulated Single Conductor
3Insulated Duplex Conductors - Ripcord
4Insulated Duplex Conductors - Paralleled with Overall Insulation Jacket
7Insulated Duplex Conductors - Twisted
8Insulated Duplex Conductors - Twisted with Overall Insulation Jacket
9Insulated Duplex Conductors - Twisted with Mylar-backed Aluminum Shield, Drain Wire, and Overall Insulation Jacket

Protective metal overbraids are used to enhance abrasion and cut-through resistance. With an approximately 85% coverage they also provide a noise shield although not as effective as the aluminized mylar tape full coverage shields.
PROTECTIVE OVERBRAID SS Flex Tubing
CodeDescriptionsCodeI.D.Approx. O.D.
0No Attendant FT-1250.125"0.200"
FT-1870.187"0.280"
1Stainless Steel 1400°F (760°C)
Wire Braided over Insulated Construction
FT-2500.250"0.340"
2Inconel Wire 1800°F (982°C)
Braided over Insulated Construction
FT-3120.310"0.420"

Thermocouple Wire Ordering Information

Example: J-20-GG40

Type J, T/C Grade, Standard Tolerance, Solid, 20 GA., Glass/Glass Insulation, Parallel, No Overbraid

CONDUCTOR
T/C Type, Grade, Tolerance, Solid or Stranded
WIRE GA.INSULATIONCONSTRUCTIONPROTECTIVE OVERBRAID
CODECODETYPECONDUCTOROVERALLCODECONSTRUCTIONCODEOVERBRAID
T14NONE–O1Insulated Single 0NONE
J16PVCPP3Insulated Duplex - Ripcord1SS
E18Silicone Rubber LL4Insulated Duplex - Paralleled w/Overall Jacket2Inconel
K20Extruded Teflon FEPEE7Insulated Duplex - Twisted
N24Extruded Teflon PFAFF8Insulated Duplex - Twisted w/Overall Jacket
TX30Taped Teflon TFETT9Insulated Duplex - Twisted w/Mylar backed Al Shield and Overall Jacket
JX36KaptonKK
EX40Synthetic Fiber SS
NXWrapped Glass W–
RXGlass Braid GG
SXHi-Temp Glass HH
BXRefrasilRR
CXCeramicCC
"-" Designates not available
J - Type J, Standard Tolerance, T/C Grade, Solid Conductors
JJ - Special Tolerance
JX - Extension Grade
JF - Stranded Conductors (Flexible)
For Single Conductors:
JPF - Type J, Positive Leg, Standard Tolerance, T/C Grade, Stranded Conductor
JNF - Type J, Negative Leg

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