Multipoint Thermocouple
Custom Multipoint Thermocouple Temperature Profiling Sensors measure the temperature at different points along its length. Its unique design is made with an ungrounded (isolated) junction with multiple measuring points arranged along the length of the probe. It accurately measures temperatures up to 2100°F with lengths varying up to 200 feet. This design uses a mineral insulated sheath material like a traditional thermocouple, except it uses a larger single (+) positive conductor as the center conductor with multiple (-) negative conductors around it. The benefit is a larger conductor size in a smaller flexible package.
These sensors are frequently used in chemical and petrochemical industries because they provide an excellent temperature profile for chemical reactors, catalytic crackers, fractionation towers, and fluidized bed catalyst tanks.
For a Custom Multipoint Thermocouple specific to your process or application,
contact ThermX for stock or application assistance. 1-800-284-3769
SPECIFICATIONS
- Compacted Mineral Insulated Sheath Material 99.4% minimum purity
- Insulation Resistance: 500 meg ohms at 500 VDC minimum
- Thermocouple Calibration:
- Type "K" & "N" Standard or Special Limits of Error (Class I & II)
- Type "J" & "E" Standard Limits of Error (Class II) - (Special Order)
- Standard Sheath Materials: 316 SS, 310 SS, Inconel™ 600 (nickel alloy 600)
DESIGN RULES
- Number of Points: Up to 15 points (depends on OD of cable, see table below)
- Minimum distance between measuring points (junctions): 1.0" (25.4 mm)
- Point Location Tolerance: O.D. of cable, or .3% of length, whichever is greater
- Inner Wire: Positive
- Outer Wires: Negative
- Minimum Bend Radius = 10 times the sheath diameter
- Shipment Standard: 24" or 33'' diameter coil (consult for special requirement)
- Pressure rating dependent on design specification
Standard Outside Diameter, Points, & Maximum Lengths |
O.D (inches) | Tolerance | Max # of Points | Normal Length | Max Length | Notes* |
.313" | ± .003" (7.95mm) | Up to 19 | 250 feet | 500 feet | Type K Max 2100°F |
.250" | ± .002" (6.35mm) | Up to 13 | 400 feet | 800 feet | Type K Max 2100°F |
.188" | ± .002" (4.78mm) | Up to 10 | 700 feet | 1400 feet | Type K Max 2100°F |
.125" | ± .002" (3.18mm) | Up to 7 | 1600 feet | 3200 feet | Type K Max 1960°F |
*Maximum temperatures per ASTM E-608, sheath material will determine max usable temperature.
Dimensional Information: Wall Thickness & Wire Diameters |
Number of Thermocouple Measuring Points | Wall Thickness (Percent of Diameter) | Outer Wire Size (Percent of Diameters) | Inner Wire Size (Percent of Diameter) | Transition Size from MI Cable to Leadwire* |
2 - 4 | 11.8% | 11.0% | 15.5% | .50" x 1.5" |
5 - 7 | 11.8% | 8.5% | 11.7% | .75" x 3.0" |
8 - 10 | 11.8% | 8.0% | 10.3% | .75" x 3.0" |
11 - 13 | 11.8% | 7.6% | 11.4% | .75" x 3.0" |
14 - 16 | 11.8% | 7.2% | 12.1 % | 1.0" x 3.0" |
* Epoxy potting temperature rating 300°F/150°C with 600°F/320°C epoxy available upon request.
Sample Drawings of Multipoint Thermocouple Configurations
