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Learn about Thermocouples, RTDS, Bearing Sensors & more.

Basic Knowledge

What is a Thermocouple?

Thermocouple assembly, types E, J, K, N & T
with general purpose conduit head and metal
sheath with mounting threads.

What is a Thermowell?

A thermowell allows the temperature sensor
to be removed and replaced without compromising
either the ambient region or the process.

What is a Flange?

Flanges can be used in extremely high pressure services,
particularly at or near atmospheric temperature.

What is an RTD?

An RTD is basically a temperature sensitive resistor.
It is a positive temperature coefficient device,
which means that the resistance increases
with temperature.

What is a Bearing Sensor?

Bearings are sensors that can be used
for high temperature applications.

Thermocouple Types

Chemical Composition
Composed of a positive leg of 90% Nickel, 10% Chromium and a negative leg of 45% Nickel, 55% copper.

Specifications
When protected by compacted mineral insulation and appropriate outer sheath, Type E is usable from 0 to 900?C, (32 to 1652°F). This Thermocouple has the highest EMF output per degree of all recognized thermocouples. If the temperature is between 316 to 593

Chemical Composition
Composed of a positive leg of 90% nickel, 10 chromium and a negative leg of 95% nickel, 2% aluminum, 2% manganese and 1% silicon.

Specifications
When protected by compacted mineral insulation and appropriate outer sheath, type K is useable from -36 to 1260°C, (-32 to 2300°F). If temperature range falls between 316 to 593°C, (600 to 1100°F), we recommend using type J or N because of aging which can cause a drift rate of 1 to 2°C, (2 to 4°F) in a few hours time. For applications below 0C (32F), special selection of alloys are usually required.

Chemical Composition
Composed of a positive leg of 90% nickel, 10 chromium and a negative leg of 95% nickel, 2% aluminum, 2% manganese and 1% silicon.

Specifications
When protected by compacted mineral insulation and appropriate outer sheath, type K is useable from -36 to 1260°C, (-32 to 2300°F). If temperature range falls between 316 to 593°C, (600 to 1100°F), we recommend using type J or N because of aging which can cause a drift rate of 1 to 2°C, (2 to 4°F) in a few hours time. For applications below 0C (32F), special selection of alloys are usually required.

Chemical Composition
Composed of a positive leg of pure copper and a negative leg of 45% nickel, 55% copper.

Specifications
When protected by compacted mineral insulation and appropriate outer sheath, Type T is usable from 0 to 350°C, (32 to 662°F). Type T is very stable and is used in a wide variety of cryogenic and low temperature applications. For applications below 0?C, (32°F) special selection of alloys are usually required.

Chemical Composition
Composed of a positive leg of 90% Nickel, 10% Chromium and a negative leg of 45% Nickel, 55% copper.

Specifications
When protected by compacted mineral insulation and appropriate outer sheath, Type E is usable from 0 to 900?C, (32 to 1652°F). This Thermocouple has the highest EMF output per degree of all recognized thermocouples. If the temperature is between 316 to 593°C, (600 to 1100°F), we recommend using type J or N because of aging which can cause drift of 1 to 2°C, (2 to 4°F) in a few hours time. For applications below 0°C, (32°F), special selection of alloys are usually required.

Chemical Composition
Composed of a positive leg of 90% platinum 10% Rhodium and a negative leg of 100% Platinum.

Specifications
When protected by compacted mineral insulation and appropriate outer sheath, Type S is usable from 0 to 1482°C, (32 to 2700°F). Easily contaminated. Reducing atmospheres are particularly damaging. Type S should be protected with gas tight ceramic tubes, a secondary tube of porcelain and silicon carbide or metal outer tubes, as conditions require.

Thermcouple Charts

Thermocouple_Types_Picture

Calibration types have been established by the American Society for Testing and Materials(ASTM)according to their temperature versus EMF characteristics in accordance with ITS-90,in standard or special tolerances.

thermocouple_diagram-1

A thermocouple circuit has at least two junctions: the measurement junction and a reference junction. Typically, the reference junction is created where the two wires connect. This second junction is really two junctions but considered as one (thermal) junction.

Temperature Curve Chart
Calibration types are designed to deliver as close to a straight line voltage curve inside their temperature application range as possible. This makes it easier for an instrument or temperature controller to correctly correlate the received voltage to a particular temperature.

Thermal_Response_Time
The smaller the diameter, the faster the thermocouple responds. Grounding the junction also improves response time by approximately 50 percent based on the sensor achieving 63.2 percent of the final reading or to the first time constant.

Thermcouple Voltage

Thermocouple Type J °C

Thermocouple Type J °F

Thermocouple Type K °C

Thermocouple Type K °F

Thermocouple Type N °C

Thermocouple Type N °F

Thermocouple Type T °C

Thermocouple Type T °F

Thermocouple Type E °C

Thermocouple Type E °F

Thermocouple Type S °C

Thermocouple Type S °F

Thermocouple Type R °C

Thermocouple Type R °F

Thermocouple Type B °C

Thermocouple Type B °F

Thermocouple Type C °C

Thermocouple Type C °F

Thermcouple Junctions

Grounded Thermocouples: This is the most common junction style. A thermocouple is grounded when both thermocouple wires and the sheath are all welded together to form one junction at the probe tip. Grounded thermocouples have a very good response time because the thermocouple is making direct contact with the sheath, allowing heat to transfer easily. A drawback of the grounded thermocouple is that the thermocouple is more susceptible to electrical interference. This is because the sheath often comes into contact with the surrounding area, providing a path for interference.

Ungrounded Thermocouples: A thermocouple is ungrounded when the thermocouple wires are welded together but they are insulated from the sheath. The wires are often separated by mineral insulation.

Exposed Thermocouples (or “bare wire thermocouples”): A thermocouple is exposed when the thermocouple wires are welded together and directly inserted into the process. The response time is very quick, but exposed thermocouple wires are more prone to corrosion and degradation. Unless your application requires exposed junctions, this style is not recommended.

Ungrounded Uncommon: An ungrounded uncommon thermocouple consists of a dual thermocouple that is insulated from the sheath and each of the elements are insulated from one other.

Thermocouple Color Codes

Thermocouple Extension Types

Thermocouple Color Code - Thermometrics

Tolerance of Thermocouples

Thermocouple Tolerance

Tolerance of Thermocouples

Thermocouple Tolerance

Wire

FEP Teflon Extruded– 204°C (400°F) / 260°C (500°F)
Conductor is FEP extruded Teflon. Overall jacket is FEP extruded Teflon. Abrasion resistance excellent. Moisture resistance is excellent. Color coded. Order Code TE/TE.

TFE Teflon Fused Tape– 260°C (500°F) / 316°C (600°F)
Conductor is TFE Teflon fused tape. Overall jacket is TFE Teflon fused tape. Abrasion resistance is good. Moisture resistance is excellent. Color coded. Order Code TF/TF.

TFE Teflon Tape– 482°C (900°F) / 538°C (1000°
Conductor is TFE Teflon tape, (not fused), with TFE coated glass. Overall jacket is Teflon coated glass braid. Abrasion resistance is good. Moisture resistance is excellent. Color coded. Order Code TFB/TFB.

Glass Braid– 482°C (900°F) / 538°C (1000°F)
Conductor is glass braid. Overall jacket is glass braid. No color coding. Abrasion resistance is fair. Moisture resistance is fair. Order Code FBN/FBN.

Glass Braid with Silicon Resin– 482°C (900°F) / 538°C (1000°)
Conductor Glass Braid with Silicone Resin Impregnation. Overall Jacket Glass Braid with Silicone Impregnation. Impregnation retained to 204°C (400°F). Abrasion Resistance Fair. Moisture Resistance Good. Color coded. Order Code FB/FB

Double Glass Braid– 482°C (900°F) / 538°C (1000°F)
Conductor Double Glass Braid with Silicone Resin Impregnation. Overall Jacket Glass Braid with Silicone Impregnation. Impregnation retained to 204°C (400°F) Abrasion Resistance Good. Moisture Resistance Good. Color coded. Order Code FB2/FB.

Double Glass Wrap– 482°C (900°F) / 538°C (1000°F)
Conductor is double glass wrap with high temperature varnish. Overall jacket of glass braid with silicone resin impregnation. Impregantion retained to 204°C (400°F). Abrasion resistance is fair. Moisture resistance is good. Color coded. Order Code FW2/FB.

High Temp Glass Braid– 704°C (1300°F) / 871°C (1600°F)
Conductor is hi-temp glass braid. Overall jacket of hi-temp glass braid with light laquer coating impregnation. Impregantion retained to 204°C (400°F). Abrasion resistance is fair. Moisture resistance is fair. Not color coded. Order Code HGN/HG .

Ceramic Fiber– 1204°C (2200°F) / 1427°C (2600°F)
Conductor is ceramic fiber. Overall jacket is ceramic fiber.Abrasion resistance is good. Moisture resistance is Fair. Not color coded. Order Code CF/CF.

PVC– -29°C (-20°F) / 105°C (221°F)
Conductor is PVC. Overall jacket is PVC. Abrasion resistance is good. Mositure resistance is excellent. Color coded.Order Code PC/PC.

Kapton Fused Tape– 316°C (600°F) / 427°C (800°F)
Conductor is kapton fused tape. No overall jacket. Wires are twisted. Both legs have a tracer. Abrasion resistance is good. Mositure resistance is excellent. Color coded. Order Code KF/TW.

RTD Charts

10Ωohm Copper Rtd-0.00385 in °F

10Ωohm Copper Rtd-0.00427 in °C

10Ωohm Copper Rtd-0.00427 in °F

10Ωohm Copper Rtd-0.00390 in °C

10Ωohm Copper Rtd-0.00390 in °F

10Ωohm Copper Rtd-0.00392 in °C

10Ωohm Copper Rtd-0.00392 in °F

10Ω ohm_nickel RTD-0.00672 in °C

100Ω ohm_nickel RTD-0.00672 in °F

120Ω ohm_nickel RTD-0.00672 in °C

120Ω ohm_nickel RTD-0.00672 in °F

507.5Ω Nickel- 0.00520 Coefficient RTD Chart in °C

507.5Ω Nickel- 0.00520 Coefficient RTD Chart in °F

604Ω Ohm Nickel-Iron- 0.00518 Coefficient RTD Chart in °C

604Ω Ohm Nickel-Iron- 0.00518 Coefficient RTD Chart in °F

1000Ω ohm_nickel RTD-0.00672 in °C

1000Ω ohm_nickel RTD-0.00672 in °F

Din Class A & B Tolerance Chart

RTD Graphs

Platinum RTD Tolerances

rtd_accuracy_chart

Thermocouple EMF VS Temperature

Thermocouple - Thermometrics

Bearing Sensors In-Depth

  • Sensor Element:    Platinum 100Ω  ±0.12% at 0°C
  • Measuring Range:    -50 to 260°C (-58 to 500°F)
  • Case Material:    Tin plated copper alloy and Stainless Steel
  • Wiring Configuration:    2, 3, and 4 wire (single)   2 or 3 wire (dual)
  • Accuracy Range:    Class B to DIN EN 60751    Class A to DIN EN 60751
  • Tip Construction:    Tip sensitive
  • Termination:    Stranded copper with PTFE insulation; stainless steel overbraid optional (one sleeve covers all leads).
  • Time Constant:    3.0 seconds(case style A) to 1.5 seconds(case style D), typical value in moving water.
  • Insulation Resistance:    10 megohms min. at 100 VDC, leads to case.
  • Options:    Calibration- single point or multiple points

References & Terms (A-Z)

2-Wire RTD – The simplest resistance thermometer configuration uses two wires. It is only used when high accuracy is not required, as the resistance of the connecting wires is added to that of the sensor, leading to errors of measurement. This configuration allows use of 100Â meters of cable. This applies equally to balanced bridge and fixed bridge system.

3-Wire RTD – In order to minimize the effects of the lead resistances, a three-wire configuration can be used. Using this method the two leads to the sensor are on adjoining arms. There is a lead resistance in each arm of the bridge so that the resistance is cancelled out, so long as the two lead resistances are accurately the same.

4-Wire RTD – The four-wire resistance thermometer configuration increases the accuracy and reliability of the resistance being measured: the resistance error due to lead wire resistance is zero. In the diagram above a standard two-terminal RTD is used with another pair of wires to form an additional loop that cancels out the lead resistance.

Accessories – Additional products used for temperature sensing.

Armored – Armor cable protects the leads of Thermocouples types E, J, K, N & T. Metal sheaths made to your required length.

Autoclave – Autoclave thermocouples are designed to withstand the harsh environment of an autoclave. They are ideally suited for food applications where steam wash down is necessary.

Averaging Sensor – Averaging sensors measure the temperature over the entire sheath length to provide an average temperature measurement of the cross sectional area of air ducts, room gradient temperatures, and other low temperature averaging applications.

Connection HeadTypically utilized in an industrial environment to help protect the probe from harsh conditions.

Embedment – Bearing sensors are miniature sensors installed in or beneath the babbitt layer of the bearing shoe. The sensors monitor the metal temperature- the most reliable indicator of bearing condition- to give early warning of oil film breakdown.

Field Adjustable Sensor – Field Adjustable Sensors are ideal for applications involving various sheath lengths that are best determined on site, rather than on an engineering drawing.

Flex Armor – Flex armor temperature sensors are commonly used in extruder and plastic processing and bearing industries.

Handheld Thermocouple – Versatile thermocouples commonly used for sanitary service requirements. Handles are available in CPVC, Delrin, Virgin Teflon and Stainless Steel.

High-Temperature Thermocouple – Ultra-high temperatures to over 4,200°F with conduit head attached available in various sheath materials.

HVAC – Our HVAC assemblies are made for easy installation, high reliability, and compatibility with most building automation systems.

Magnet Mount – Magnet Mount Thermocouples can be utilized on any ferrous metals as an easy means to measure surface temperature of an object. They are available in J, K, E, T calibrations.

Multi-Point – Probes consist of several smaller diameter thermocouples placed inside a single outer sheath. They are best suited for profiling the temperature at various points along a single axis.

Overbraided – Incorporate high temperature ceramic insulation with inconel overbraid thermocouple wires to create a flexible, abrasion resistant thermocouple.

Penetration Thermocouple – Penetration Thermocouple probes are utilized when an application requires insertion into a soft, medium, or semi-solid media to allow for best possible internal temperature response.

Pierce Probe – Piercing probe temperature sensor is manufactured with heavy wall tubing to provide support for production line handling and a spring relief.

Platinum Thermometer – Temperature sensors that exploit the predictable change in electrical resistance of some materials with changing temperature. As they are almost invariably made of platinum, they are often called platinum resistance thermometers (PRTs). They are slowly replacing the use of thermocouples in many industrial applications below 600°C, due to higher accuracy and repeatability.

PT100 – PT100 sensors offer excellent accuracy over a wide temperature range (from -200 to +850 C).

PT1000 – The Pt1000 has 1000 ohms resistance at 0 C. These sensors are normally fitted into some type of protective sheath or mounting to form a probe.

Replacement – The Flexible lead wire (NB1) replacement probe is ideal for field installation with existing protection heads or for extending leads to remote locations. Flexible leads prevent breakage in hard to wire situations.

RTDs – Temperature sensors that exploit the predictable change in electrical resistance some materials with changing temperature.

 

PT1000 – The Pt1000 has 1000 ohms resistance at 0 C. These sensors are normally fitted into some type of protective sheath or mounting to form a probe.

Sanitary – A sanitary system accepted practices pertain to the sanitation aspects of equipment used to produce frozen desserts, egg, milk, cottage cheese, and similar food and dairy products. Included are Culinary Steam, Boiler Feed Water, Heat Exchangers, Transfer Station, Silo Tank, Atmospheric Pasteurizers, Pipeline Milking Systems and Feed Production.

Screw In – Also known as, Pipe Plug Probes are ideal for vessel applications, pressurized containers and applications requiring mounting in a NPT orifice for fixed readings. Pipe probes are available in J, K, T, E calibration as well as grounded, ungrounded, or exposed junction termination.

Signal Conditioners – A signal conditioner is a device that converts one type of electronic signal into a another type of signal. Its primary use is to convert a signal that may be difficult to read by conventional instrumentation into a more easily read format. In performing this conversion a number of functions may take place.

Spring Loaded – Spring-Loaded Thermocouples are designed to measure the surface temperatures of moving or stationary walls by direct contact. The sensing tip is spring-loaded to maintain contact even if the wall is moving. Applications include bearings, rotating shafts, printed circuit boards, molding machines, plates, etc. Available in models as small as 3/4″ overall length. Thermocouple types include ANSI Types J, K, E and T.

Surface Mount – Surfacemount Thermocouple sensors are designed for use in a variety of applications. Our extensive experience in mounting sensors to precision sheet metal stampings provides efficiency to your process by having us perform this initial assembly step. The product shown is a Pt 100 ohm, RTD mounted with high temperature ceramic cement and spliced to 12” of lead wire.

Temperature Elements – RTD elements are used to manufacture temperature sensors. A resistance element is the temperature sensing component at the heart of an RTD or resistance thermometer.

Thermocouples – Thermocouple assembly, types E, J, K, N & T with general purpose conduit head and metal sheath with mounting threads.

Thermowells – Thermowells are pressure-tight receptacles that extend the life of a temperature in environments where the sensor is not chemically compatible with the process media or the sensor does not have the mechanical strength to withstand the process flow or pressure. Thermowells also facilitate removing, changing, checking or replacing sensors without draining the process system.

Thin Film – Thin film elements are mass produced by automated equiptment which deposites a layer of platinum onto a ceramic substrate and uses a layer photolithography to etch an electrical current path corresponding to the required value of ohms. The elements are smaller than traditional wire and as a result have a faster response time and fit more applications, while reducing user costs at the same time.

Transition Joint – Transition Joint Thermocouples are typically made up of a metal sheathed thermocouple of a given diameter which “transitions” to a lead wire via a slightly larger cylindrical barrel. This barrel transition is typically made of metal or thermoplastic.

Tube Skin/Weld Pad – Weld Pad Sensors are commonly used in Petro-Chemical industries. The sensors are welded or clamped to measure process temperature and are available in 3 basic configuration. Theses configurations can be manufactured as RTDs, Thermocouples, Thermisters & Direct to Digital Semi Conductor Sensors, based on the temperature limitations and specific process requirements.

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