Thermocouples / Series 77
Series 77: Industrial Thermocouple Probes
77A, 77B, 77C, 77D
RdF Corporation offers a complete line of Mineral-Insulated Thermocouples for industrial applications.
Available in either single or dual junction assemblies, the Series 77 Thermocouples feature special accuracy limits, strong and flexible stranded 20 AWG wire leads and all-welded construction.
Features
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 and jacketed cable
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 <2.5 sec. in water flowing at 3 ft/sec. Isolated instrumentation required.
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 <5 sec. in water flowing ar 3 ft/sec.
Exposed- The thermocouple junction extends beyond the sheath providing fast response. For low pressure gasses to reduced maximum temperatures.
Thermocouple Data - Thermocouple Types
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 | ||||||
| Thermocouple Material | Range and Limits of Error | |||||
| ANSI Type |
Positive | Negative (red color) |
Positive (color code) |
Temperature Range, °F (1/8" dia./1/4" dia.) |
Standard (whichever is greater) |
Special (Whichever is greater) |
| J | Iron (magnetic) |
Constantan | White | 32 to 970/1330 | ±4°F or ±0.75% | ±2°F or ±0.4% |
| K | Chromel | Alumel (magnetic) |
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% |
Type 77A/B/C
Ordering Specifications
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77 A/B/C |
SERIES RIGID THERMOCOUPLE WITH 1/2 X 1/2 HEX FITTING FOR DIRECT IMMERSION STYLE (SEE ABOVE) |
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| SHEATH DIAMETER (1/16" STEPS) | ||||||||||||||||
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2 3 4 |
1/8" (“A” Requires Transition - 1.75 x 0.25) 3/16" (Dual “A” Requires Transition - 1.75 x 0.25, Style A or B only) 1/4" |
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| SHEATH MATERIAL | ||||||||||||||||
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S I O |
316 SS Inconel 600 Other (A or C only, No Transition) | |||||||||||||||
| ANSI TYPE THERMOCOUPLE (special limits of error) | ||||||||||||||||
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| PROBE LENGTH IN INCHES | ||||||||||||||||
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TYPE OF JUNCTION G Grounded Junction U Ungrounded Junction X Exposed Junction |
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| CONNECTION HEAD (see table below) | ||||||||||||||||
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LEAD LENGTH (Specify in inches) (4" leads with connection head - standard) |
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– | Typical Write-Up for 77B | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Connection Heads for 77A/B/C
NEMA 4 with Gasket |
Conduit | Max. Temp | |
| A | Small cast aluminum head | 1/2 NPT | 125 °C |
| B | High temp. small cast aluminum head | 1/2 NPT | 260 °C |
| C | Cast Iron head | 3/4 NPT | 260 °C |
| D | For no connection head specify "D" | ||
| E | Large cast aluminum head | 3/4 NPT | 260 °C |
| F | Economy conduit body | 1/2 NPT | 125 °C |
| G | Explosion proof small cast aluminum head | 1/2 NPT | 125 °C |
| H | High temp. expl. proof small cast alum. head | 1/2 NPT | 260 °C |
| I | Hinged plastic | 3/4 NPT | 125 °C |
| J | Hinged cast aluminum | 3/4 NPT | 125 °C |
| K | Din B cast aluminum | 1/2 NPT | 100 °C |
| S | Other (please specify when ordering) | ||
| T | Transmitter, specify or supply whead | Terminals: All heads include at least 4 two-screw strap terminations. 6 can be requested in styles “C” and “E”. Style “K” includes 6 two-screw post straps. Styles “A”, “B”, “G” & “H” can have up to 8 screw-in post straps | |
TYPE A- Straight Probe Assembly
Adjustable fittings are available with 1/2", 1/4", or 1/8" NPT mounting. Seal at lead exit temperature rated to 500°F.
TYPE B- Probe with Hex Fitting
This probe is for direct immersion. Use spring loaded (77D) with thermowells. Lead exit temperature 500°F.
TYPE C- Probe with Quick Disconnect Plug and Jack
Available in 1/8" and 1/4" diameter with connector. Rated to 475°F
TYPE 77D
Type D: Spring-loaded MGO Insulated Sheathed Thermocouple
Designed for mounting in thermowell. Configurable options include probe lag hardware.
Ordering Specifications
Probe Lag Hardware
| 77D |
SPRING LOADED MGO INSULATED SHEATHED THERMOCOUPLE FOR MOUNTING IN THERMOWELL Note: Thermowell not included, see Data Sheet T-WELLS. |
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| 4 SHEATH DIAMETER (1/4" DIA ONLY) | ||||||||||||||||||
| SHEATH MATERIAL | ||||||||||||||||||
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S I |
316 SS Inconel 600 |
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| ANSI TYPE THERMOCOUPLE (special limits of error) | ||||||||||||||||||
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| STEM (“A”) LENGTH OF PROBE IN INCHES (same dimension as thermowell “A”) | ||||||||||||||||||
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TYPE OF JUNCTION G Grounded Junction U Ungrounded Junction |
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| CONNECTION HEAD (see table below) | ||||||||||||||||||
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PROBE LAG HARDWARE 1/2" NPT Fittings, Stainless Steel
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LEAD LENGTH (Specify in inches) (4" leads with connection head standard) |
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– | Typical write-up for 77D | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Connection Head for 77D
NEMA 4 with Gasket |
Conduit | Max. Temp | |
| A | Small cast aluminum head | 1/2 NPT | 125 °C |
| B | High temp. small cast aluminum head | 1/2 NPT | 260 °C |
| C | Cast Iron head | 3/4 NPT | 260 °C |
| D | For no connection head specify "D" | ||
| E | Large cast aluminum head | 3/4 NPT | 260 °C |
| F | Economy conduit body | 1/2 NPT | 125 °C |
| G | Explosion proof small cast aluminum head | 1/2 NPT | 125 °C |
| H | High temp. expl. proof small cast alum. head | 1/2 NPT | 260 °C |
| I | Hinged plastic | 3/4 NPT | 125 °C |
| J | Hinged cast aluminum | 3/4 NPT | 125 °C |
| K | Din B cast aluminum | 1/2 NPT | 100 °C |
| S | Other (please specify when ordering) | ||
| T | Transmitter, specify or supply whead | Terminals: All heads include at least 4 two-screw strap terminations. 6 can be requested in styles “C” and “E”. Style “K” includes 6 two-screw post straps. Styles “A”, “B”, “G” & “H” can have up to 8 screw-in post straps | |
