Omega Engineering Inc.

 

Reference Guide

Temperature Dependent Data

Mineral insulated wire is a 3-part system composed of compacted ceramic insulation, thermocouple wire and metal sheath. Therefore, three factors determine the useful service temperature for mineral insulated wire.

  • Range for the thermocouple wire (see table - limits of error)
  • Maximum service temperature of insulation. In the case of MgO, this is in excess of 1650°C (3000°F).
  • Properties of the sheath material

*Vacuum or Inert atmosphere only.

Material Melting
Point		 Continuous
Max. Temp.		 Tensile (PSI) Strength
at 93°C (200°F) at 538°C (1000°F)
304 SS 1400°C (2560°F) 900°C (1650°F) 68,000 15,000
316 SS 1370°C (2500°F) 900°C (1650°F) 75,000 23,000
Inconel* 1400°C (2550°F) 1150°C (2100°F) 93,000 5,000

 Conductor Size Equivalents

AWG = American Wire Gauge
SWG = (British) Standard Wire Gauge
To convert from AWG to SWG: Determine wire diameter in inches (mm) from appropriate SWG. Example: To convert 30 AWG to SWG, determine that 30 AWG is 0.0100" (0.254 mm). 0.0100" is equivalent to 33 SWG.

Gauge
No.		 AWG SWG Gauge
No.		 AWG SWG
inches mm inches mm inches mm inches mm
0 0.3249 8.25 0.324 8.23 23 0.0226 0.574 0.024 0.610
1 0.2893 7.35 0.300 7.62 24 0.0201 0.511 0.022 0.559
2 0.2576 6.54 0.276 7.01 25 0.0179 0.455 0.020 0.508
3 0.2294 5.83 0.252 6.40 26 0.0159 0.404 0.0180 0.457
4 0.2043 5.19 0.232 5.89 27 0.0142 0.361 0.0164 0.417
5 0.1819 4.62 0.212 5.38 28 0.0126 0.320 0.0148 0.376
6 0.1620 4.11 0.192 4.88 29 0.0113 0.287 0.0136 0.345
7 0.1443 3.67 0.176 4.47 30 0.0100 0.254 0.0124 0.315
8 0.1285 3.26 0.160 4.06 31 0.0089 0.226 0.0116 0.295
9 0.1144 2.91 0.144 3.66 32 0.0080 0.203 0.0108 0.274
10 0.1019 2.59 0.128 3.25 33 0.0071 0.180 0.0100 0.254
11 0.0907 2.30 0.116 2.95 34 0.0063 0.160 0.0092 0.234
12 0.0808 2.05 0.104 2.64 35 0.0056 0.142 0.0084 0.213
13 0.0720 1.83 0.092 2.34 36 0.0050 0.127 0.0076 0.193
14 0.0641 1.63 0.080 2.03 37 0.0045 0.114 0.0068 0.173
15 0.0571 1.45 0.072 1.83 38 0.0040 0.102 0.0060 0.152
16 0.0508 1.29 0.064 1.63 39 0.0035 0.089 0.0052 0.132
17 0.0453 1.15 0.056 1.42 40 0.0031 0.079 0.0048 0.122
18 0.0403 1.02 0.048 1.22 41 0.0028 0.071 0.0044 0.112
19 0.0359 0.912 0.040 1.02 42 0.0025 0.064 0.0040 0.102
20 0.0320 0.813 0.036 0.914 43 0.0022 0.056 0.0036 0.091
21 0.0285 0.724 0.032 0.813 44 0.0020 0.051 0.0032 0.081
22 0.0253 0.643 0.028 0.711 45 0.0018 0.046 0.0028 0.071
 
 
Maximum Temperature Ratings of Thermocouples
Thermocouple Type 8 AWG
3.25 mm		 14 AWG
1.63 mm		 20 AWG
0.81 mm		 24 AWG
0.51 mm		 28 AWG
0.32 mm		 30 AWG
0.25 mm
J 760°C (1400°F) 590°C (1100°F) 480°C (900°F) 370°C (700°F) 370°C (700°F) 320°C (600°F)
K 1260°C (2300°F) 1090°C (2000°F) 980°C (1800°F) 870°C (1600°F) 870°C (1600°F) 760°C (1400°F)
E 870°C (1600°F) 650°C (1600°F) 540°C (1000°F) 430°C (800°F) 430°C (800°F) 370°C (400°F)
T   370°C (700°F) 260°C (500°F) 200°C (400°F) 200°C (400°F) 150°C (300°F)
RX, SX     200°C (400°F) 200°C (400°F) 200°C (400°F) 150°C (300°F)
N 1260°C (2300°F) 1090°C (2000°F) 980°C (1800°F) 980°C (1800°F) 980°C (1800°F) 870°C (1600°F)
Maximum Long-Term Service Temperature for Protected Bare Wire Thermocouples of Various Wire Diameters
Symbol 0.127 mm
(0.005")		 0.381 mm
(0.015")		 0.508 mm
(0.020")		 0.813 mm
(0.032")
T   200°C (393°F) 200°C (393°F) 260°C (500°F)
J 315°C (599°F) 370°C (698°F) 370°C (698°F) 480°C (898°F)
E 370°C (698°F) 425°C (797°F) 425°C (797°F) 535°C (995°F)
K 590°C (1094°F) 870°C (1598°F) 870°C (1598°F) 980°C (1796°F)
R, S     1480°C (2696°F)  
B     1700°C (3092°F)  
C, G, D† 1980°C (3596°F) 2315°C (4199°F) 2315°C (4199°F)  
Resistance vs. Wire Diameter — Resistance in Ohms per DOUBLE FOOT (30 cm) Length at 20°C (68°F)

SWG No.

Diameter
mm (inches)

Type K
CHROMEGA
ALOMEGA

Type J
Iron/
Constantan

Type T
Copper/
Constantan

Type E
CHROMEGA/
Constantan

Type S
Pt10%
Rh/Pt

Type R
Pt13%
Rh/Pt

Type C*
W5% Re/
W26% Re

Type G*
W/
W26% Re

Type D*
W3% Re/
W25% Re

7-8
10
12-13
14
16
17-18
19
21
25
27-28
33
35-36
37-38
39
43
44
—
—
—

4.11 (0.162)
3.25 (0.128)
2.59 (0.102)
2.06 (0.081)
1.63 (0.064)
1.30 (0.051)
1.02 (0.040)
0.81 (0.032)
0.51 (0.0201)
0.40 (0.0159)
0.25 (0.0100)
0.20 (0.0080)
0.16 (0.0063)
0.13 (0.0050)
0.09 (0.0039)
0.08 (0.00315)
0.05 (0.0020)
0.03 (0.0010)
0.01 (0.00049)

0.023
0.037
0.058
0.091
0.146
0.230
0.374
0.586
1.490
2.381
5.984
9.524
15.17
24.08
38.20
60.88
149.6
598.4
2408

0.014
0.022
0.034
0.054
0.087
0.137
0.222
0.357
0.878
1.405
3.551
5.599
8.946
14.20
23.35
37.01
88.78
355.1
1420

0.012
0.019
0.029
0.046
0.074
0.117
0.19
0.298
0.7526
1.204
3.043
4.758
7.66
12.17
19.99
31.64
76.09
304.3
1217

0.027
0.044
0.069
0.109
0.175
0.276
0.448
0.707
1.78
2.836
7.169
11.31
18.09
28.76
45.41
73.57
179.2
716.9
2816

0.007
0.011
0.018
0.028
0.045
0.071
0.116
0.185
0.464
0.740
1.85
1.96
4.66
7.40
11.6
18.6
74
185
740

0.007
0.011
0.018
0.029
0.047
0.073
0.119
0.190
0.478
0.760
1.91
3.04
4.82
7.64
11.95
19.3
76.5
191
764

0.009
0.015
0.023
0.037
0.058
0.092
0.148
0.235
0.594
0.945
2.38
3.8
6.04
9.6
15.3
24.4
60.2
240
1000

0.008
0.012
0.020
0.031
0.049
0.078
0.126
0.20
0.560
0.803
2.03
3.22
5.10
8.16
12.9
20.6
51.1
204
850

0.009
0.015
0.022
0.035
0.055
0.088
0.138
0.220
0.560
0.890
2.26
3.60
5.70
9.10
15.3
23.0
56.9
227
945

*Not official standard.

 

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