Base Metal


 

ARi’s standard thermocouple line is used in applications where high reliability is a priority. Our thermocouple line comes with the highest purity MgO insulation to yield maximum EMF stability and minimum drift problems caused by insulation impurities. We have thermocouples available in standard and special calibration limits for types K, J, E, and T per ASTM E-230. Upon request we can also custom manufacture all of our probes to meet your special requirements.

At Ari Industries, we manufacture many of our thermocouples using our own mineral insulated (MI) cable, use of this cable allows for bending of the sheath, and yields very long lengths of finished material. This enables us to supply most of our designs in any length or diameter you require. If you need assistance in choosing a product, our knowledgeable sales staff is always available to help.

Standard Sheath And Wire Diameter

ARi Symbol Unit Of Measurement L A B D E F G I K P R
Sheath Diameter inches 0.020 0.040 0.062 0.125 0.188 0.250 0.313 0.375 0.500 0.625 0.750
mm 0.50 1.00 1.67 3.17 4.75 6.35 8.00 9.52 12.70 15.90 19.10
Wire Diameter inches 0.004 0.006 0.10 0.020 0.032 0.040 0.051 0.064 0.091 0.114 0.120
mm 0.10 0.15 0.025 0.50 0.85 1.00 1.45 1.63 2.31 2.90 3.05
Maximum Length feet 30 200 290 290 135 81 45 30 30 20 13
meters 9 61 88 88 41 25 14 9 9.1 6.1 4.0

 

Wire Calibration (Special Limits Of Error)

Calibration Type ASTM E-230 Symbol ARi Symbol Similar Calibrations
Chromel P-Alumel K KS BS 1827 DIN 43710 NFE 18-001 JIS-C1602
Iron-Constantan J JS BS 1829 NFE 18-001
Chromel P-Constantan E ES
Copper Constantan T TS BS 1828 DIN 43710 NFE 18-001 JIS-C1602

 

Measuring Junction Symbols

Exposed Grounded Ungrounded
Thermocouple Exposed Junction #7 Thermocouple Grounded Junction #8 Thermocouple Un-Grounded Junction #9

 

Standard Sheath Materials

Sheath ARi Symbol Melting Point Useable Temp In Air Equivalent Analysis
°F °C °F °C
AISI 347 ST/ST F 2550 1400 1650 900 BS 3605 832Nb; DIN 4550; UNS S34700
INCONEL 600 (3) B 2570 1410 2100 (1) 1150 BS 3074-NA14; DIN 4816; UNS NO6600
AISI 304 ST/ST A 2550 1400 2100 1150 BS 3605-801; DIN 4301; UNS S30400
AISI 310 ST/ST D 2570 1410 2100 1150 BS 3605-805; DIN 4301; UNS S30400
AISI 316 ST/ST C 2550 1400 1650 900 BS 3605-845; DIN 4401; (2-3% Mo); UNS S31600
HASTELLOY X V 2470 1355 2200 1222 Trademark of Cabot Corp.

(1) Not recommended for use in sulfur atmosphere.

(2) Do not use 800 to 1600 °F temperature range due to carbon intergranular precipitation.

(3) Trademark of International Nickel Corp.

 

Time Constant

Some typical time constants (time for thermocouple temperature to reach 63.2% of step change in gas or liquid temperature) for various sizes are listed for different media.

Sheath Diameter Condition (A) Condition (B) Condition (C) Condition (D)
(inch) (seconds) (seconds) (seconds) (seconds)
5/16 0.5 5.5 5.0 55.0
1/4 0.3 4.0 2.5 39.0
3/16 0.2 2.5 2.0 26.0
1/8 0.1 1.5 1.0 14.0
1/16 0.05 0.5 0.5 5.0
1/25 0.01 0.3 0.1 2.5

Condtion A:  No. 7 hot junction in water moving at a velocity (Vo) of 1.5 m/sec (5 ft/sec)

Condtion B:  No. 8 hot junction in water moving at a velocity (Vo) of 1.5 m/sec (5 ft/sec)

Condition C:  No. 7 hot junction in air moving at a mass velocity (Go) of 29.3 Kg/sec ² (6 lbs/sec ft²)

Condition D:  No. 8 hot junction in air moving at a mass velocity (Go) of 29.3 Kg/sec ² (6 lbs/sec ft²)

For time constants (r) at other velocities (V) or mass velocities (G) use the following equations:

time constant equations

The result of these equations will be affected by using liquids other than water and gases other than air.  However, the effect is small and can be neglected for many applications.

 

Insulation Material

Symbol “N” 99.4% minimum high purity MgO meeting requirements of ASTM E-585 and E-608. Impurities are minimized to yield maximum EMF stability and minimum drift problems.

Lead Wire Length “L”

16 inch (40cm) long lead length is normally supplied. If longer lengths are required, please designate in part number.

Insulation Resistance

100 meg-ohms or more at 500 VDC for lengths of 15 meters (50 feet) or less for 1.67 to 8.0mm (1/16″ to 5/16″) diameter. 10 meg-ohms or more at 1 1/2 VDC for lengths of 15 meters (50 feet) or less for 1.0 and .63mm (0.04″ and 0.025″) diameters. This measurement is made prior to fabrication of the hot junction.

Insulation Bend Resistance

Minimum insulation resistance, after bending around a mandrel whose diameter is 4 times, the sheath diameter, to be 2.5 meg-ohms at 1 1/2 VDC.

High Temperature Insulation Resistance

All AerOpak® thermocouple lengths of 61cm (24″) or less will have a minimum insulation resistance of 10,000 ohms or more at 1 1/2 VDC at 1000ºC (1800ºF).

Availability

2 wire (1 T/C circuit) sheath diameters: 0.50 to 19.1mm (0.020″ to 0.750″).
4 wire (2 T/C circuits) sheath diameters: 3.17 to 19.1mm (0.125″ to 0.750″).
All thermocouples are available with exposed, grounded, or un-grounded measuring junctions.

Specifications

Thermocouples can be made to meet specific customer requirements, or to specifications such as MIL-T-23234A, RDT C7-6T, ASTM E-235, ASTM E-585 or E-608.

Pressure Rating

AerOpak® thermocouples using number 8 or 9 measuring junctions are pressure tight to 3500 Kg/cm2 (50,000 psi) at temperatures up to 649ºC (1200ºF). AerOpak®  thermocouples using number 7 measuring junctions are pressure tight to 350 Kg/cm2 (50,000 psi) if a seal is used at the cold end.