RdF Corporation
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Overview of RdF Temperature Sensor Applications
The Entire RdF Product Catalog, Online, and with Printer-Friendly Versions of Each Data Sheet
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Overview Performance Specs Ordering Specs   

• ANSI types J, T, K, E; Traceable to NIST
• Special Limits of Error
• Single or dual junctions
• Stainless steel fittings
• Inconel or stainless steel sheaths
• TIG welded construction

• Strong and flexible stranded 20 AWG
leads, fiberglass insulated cable,
  500°F lead exit rating
• Stainless steel or aluminum lag unions
• Cast aluminum heads with up to
8 terminal posts

  Measuring Junctions
GROUNDED – The thermocouple wires are welded directly to the sheath end closure and are completely protected. Recommended for fast responding direct immersion probes. Time constant on 1/4" dia. <2.5 sec. in water flowing at 3 ft/sec. Isolated instrumentation required. Grounded

UNGROUNDED – The thermocouple junction is electrically insulated from the external sheath with compacted magnesium oxide powder. Recommended in all applications to minimize instrumentation ground loops. Time constant on 1/4" dia. <5 sec. in water flowing
at 3 ft/sec.

EXPOSED – The thermocouple junction extends beyond the sheath providing fast response. For low pressure gasses to reduced maximum temperatures. Not available on thermowell probes.

Iron-Constantan (ANSI Symbol J)
The Iron-Constantan “J” curve thermocouple with a positive iron wire and a negative constantan wire is recommended for reducing atmospheres. The operating range for this alloy combination is 1600°F for the largest wires sizes. Smaller size wires should operate in correspondingly lower temperatures, Limit exposed junctions to 900°F continuous use.

Copper-Constantan (ANSI Symbol T)
The Copper-Constantan “T” curve thermocouple with a positive copper wire and a negative constantan wire is recommended for use in mildly oxidizing and reducing atmospheres up to 750°F. They are suitable for applications where moisture is present. This alloy is recommended for low temperature work since the homogeneity of the component wires can be maintained better than other base metal wires. Therefore, errors due to inhomogeneity of wires in zones of temperature gradient are greatly reduced. Limit exposed junctions to 500°F long term use.

Chromel-Alumel (ANSI Symbol K)
The Chrome-Alumel “K” curve thermocouple with a positive chromel wire and a negative alumel wire is recommended for use in clean oxidizing atmospheres. The operating range for this alloy is 2300°F for the largest wire sizes. Smaller wire sizes should operate at correspondingly lower temperatures. The only suitable choice for exposed junctions from 1000°F to 1800°F.

Chromel-Constantan (ANSI Symbol E)
The Chromel-Constantan thermocouple may be used for temperatures up to 1600°F in a vacuum, inert, mildly oxidizing or reducing atmosphere. At sub-zero temperatures, the thermocouple is not subject to corrosion. This thermocouple has the highest emf output of any standard metallic thermocouple. Limit exposed junctions to 1000°F continuous use.

Temperature Range & Limits of Error - RdF SERIES 77 ARE ALL SPECIAL LIMITS
Positive Negative
(red color)
(color code)
Temperature Range, °F
(whichever is greater)
(whichever is greater)
J Iron
Constantan White 32 to 970/1330 ±4°F or ±0.75%
±2°F or ±0.4%
K Chromel Alumel
Yellow –320 to 32
32 to 1900/2100
±4°F or ±2%
±4°F or ±0.75%

±2°F or ±0.4%
T Copper
(copper color)
Constantan Blue –320 to 32
32 to 600/700
±1.8°F or ±1.5%
±1.8°F or ±0.75%

±0.9°F or ±0.4%
E Chromel Constantan
(silver color)
Purple –320 to 32
32 to 1200/1510
±3°F or ±1%
±3°F or ±0.5%

±1.8°F or ±0.4%
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*Limits of error are new material interchangeability only
products proudly manufactured in the USA Specialists in Temperature Measurement
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