Showing posts with label thermocouple. Show all posts
Showing posts with label thermocouple. Show all posts

Monday, September 10, 2018

Thermowells

Thermowell
Thermowell (Duro-Sense)
One of the most important accessories for any temperature-sensing element is a pressure-tight sheath known as a thermowell. This may be thought of as a thermally conductive protrusion into a process vessel or pipe allowing a temperature-sensitive instrument to detect process temperature without opening a hole in the vessel or pipe. Thermowells are critically important for installations where the temperature element (RTD, thermocouple, etc.) must be replaceable without de-pressurizing the process.

Thermowells may be made out of any material that is thermally conductive, pressure-tight, and not chemically reactive with the process. Most thermowells are formed out of either metal (stainless steel or other alloy) or ceramic materials. A simple diagram showing a thermowell in use with a temperature sensor (RTD) is shown here:
Thermowell

As useful as thermowells are, they are not without their caveats. All thermowells, no matter how well they may be installed, increase the first-order time lag of the temperature sensor by virtue of their mass and specific heat value. It should be intuitively obvious that a few pounds of metal will not heat up and cool down as fast as a few ounces’ worth of RTD or thermocouple, and therefore the addition of a thermowell to the sensing element will decrease the responsiveness of any temperature- sensing element. What is not so obvious is that such time lags, if severe enough, may compromise the stability of feedback control. A control system receiving a “delayed” temperature measurement will not see the live temperature of the process in real time due to this lag.

Thermowell
RTD with Thermowell 
A potential problem with thermowells is incorrect installation of the temperature-sensing element. The element must be inserted with full contact at the bottom of the thermowell’s blind hole. If any air gap is allowed to exist between the end of the temperature element and the bottom of the thermowell’s hole, this will add a second time lag to the measurement system26. Some thermowells include a spring clip in the bottom of the blind hole to help maintain constant metal-to-metal contact between the sensing element and the thermowell wall.

Reprinted from Lessons In Industrial Instrumentation by Tony R. Kuphaldt – under the terms and conditions of the Creative Commons Attribution 4.0 International Public License.

Tuesday, August 28, 2018

Temperature Transmitters

Temperature Transmitters
Temperature Transmitters (Duro-Sense)
A temperature transmitter is generally described as a device, which on the input side is connected to some sort of temperature sensor and on the output side generates a signal that is amplified and modified in different ways. Normally the output signal is directly proportional to the measured temperature within a defined measurement range. Many additional features can be added depending on the type of transmitter being used. The features of the temperature transmitter are often described by using different terms with respect to technology, mounting method, functions, etc. The following list is a brief summary of these terms.

Analog Transmitters: These transmitters are designed on analog circuit technology. They normally offer basic functions such as temperature linearization and sensor break technology. Sometimes they are adjustable for different measuring ranges, often with a fast response time.

Digital Transmitters: This transmitter type is mainly based on a microprocessor. They are often called intelligent transmitters, because they normally offer many extra features, which are not possible to realize in analog transmitters.

In-Head Transmitters: These transmitters are designed for mounting in the connection heads of temperature sensors. All Duro-Sense in-head transmitters fit into DIN B heads or larger. Special care has to be devoted to the ruggedness because of the harsh conditions that sometimes exist.

DIN Rail Transmitters: DIN rail transmitters are designed to be snapped onto a DIN rail. Duro-Sense DIN rail transmitters fit on a 35mm rail according to DIN EN 50022.

RTD Transmitters: RTD transmitters are used only for RTD sensors. (Pt100, Pt1000, Ni100, etc.). Normally they can handle only one RTD type. Most Duro-Sense transmitters can handle more than one type of RTD and are either fix- ranged or adjustable. They all have linear output.

Thermocouple TransmitterThermocouple Transmitters: Thermocouple transmitters measure a MV signal form the thermocouple and compensates for the temperature of the cold junction. The cold junction compensation is normally made by measuring the terminal temperature. Alternatively, some transmitters can be adjusted to compensate for an external fixed cold junction temperature. Pure thermocouple transmitters are often not temperature linearized due to the complicated unlinearity of the thermocouples.

Analog Output: The output signal is a current (4-20mA). Some transmitters are available with 0-20mA or 0-10mA output. The signal is normally proportional to the measured value within a defined measurement range.

Digital Output: The measured value (temperature) is presented as a binary coded message. So called Fieldbus transmitters use this technique. The Fieldbus transmitters on the market today use different standards for the communication thus creating some problems when integrating them with other instrumentation. Examples of standard available are: PROFIBUS, Interbus, Foundation Fieldbus, LonWorks and CAN-bus.

Analog and Digital Output: The HART transmitters have an analog output with a superimposed digital signal on the same wires. Typically, the analog signal is used for normal measurements and the digital signal only for temporary measurements, because of the low communication speed. The digital signal is mainly used for configuration and status information.

Isolated Transmitters: Isolated transmitters have no leading connections between circuits that are isolated from each other. The isolation effectively eliminates the risk for circulating currents and facilitates the connection of transmitters to control systems with grounded inputs.

Non-Isolated Transmitters: These transmitters have leading connections between, for instance, input and output circuits. They should be used with care.

For more information on temperature transmitters, visit https://duro-sense.com or call 310-533-6877.

Friday, August 3, 2018

Video: Comparison of Thermocouples and RTDs

The video below describes the basic differences between industrial thermocouples and RTDs.


Duro-Sense Corporation provides the thermocouples, RTDs, thermowells, and accessories to the aerospace, aviation, process control, medical, R&D, power generation, alternative energy, plastics, primary metals, high-tech and OEM industries.

https://duro-sense.com
310-533-6877

Friday, July 6, 2018

Common Terminology Used in Temperature Measurement and Process Control

Terminology Used in Temperature Measurement
Accuracy: The closeness of an indicator or reading of a measurement device to the actual value of the quantity being measured; usually expressed as ± percent of the full scale output or reading.

Drift: The change in output or set point value over long periods of time due to such factors as temperature, voltage, and time.

Hysteresis: The difference in output after a full cycle in which the input value approaches the reference point (conditions) with increasing, then decreasing values or vice versa; it is measured by decreasing the input to one extreme (minimum or maximum value), then to the other extreme, then returning the input to the reference (starting) value.

Linearity: How closely the output of a sensor approximates a straight line when the applied input is linear.

Noise: An unwanted electrical interference on signal wires.

Nonlinearity: The difference between the actual deflection curve of a unit and a straight line drawn between the upper and lower range terminal values of the deflection, expressed as a percentage of full range deflection.

Precision: The degree of agreement between a number of independent observations of the same physical quantity obtained under the same conditions.

Repeatability: The ability of a sensor to reproduce output readings when the same input value is applied to it consecutively under the same conditions.

Resolution: The smallest detectable increment of measurement.

RTD: Abbreviation for "resistance temperature detector". Resistance temperature detectors are temperature sensors that are widely used because of their high accuracy, stability, and linearity. They work on the principle that the resistivity of metals is dependent upon temperature; as temperature increases, resistance increases. Resistance Temperature Detector’s can withstand temperatures up to approximately 800 C (~1500 F).

Sensitivity: The minimum change in input signal to which an instrument can respond. Stability: The ability of an instrument to provide consistent output over an extended
period during which a constant input is applied.

Thermocouple: A temperature sensing device widely used because they are relatively low cost, self-powered, durable and capable sensing high temperatures. Thermocouples generate and micro voltage in relation to temperature change.

Zero balance: The ability of the transducer to output a value of zero at the electronic null
point.

Tuesday, June 26, 2018

Understanding Dissimilar Metal Junctions and the Need for Reference Junctions

When two dissimilar metal wires are joined together at one end, a voltage is produced at the other end that is approximately proportional to temperature. That is to say, the junction of two different metals behaves like a temperature-sensitive battery. This form of electrical temperature sensor is called a thermocouple:
Dissimilar Metal Junctions

This phenomenon provides us with a simple way to electrically infer temperature: simply measure the voltage produced by the junction, and you can tell the temperature of that junction. And it would be that simple, if it were not for an unavoidable consequence of electric circuits: when we connect any kind of electrical instrument to the thermocouple wires, we inevitably produce another junction of dissimilar metals. The following schematic shows this fact, where the iron-copper junction J1 is necessarily complemented by a second iron-copper junction J2 of opposing polarity:

Dissimilar Metal Junctions

Junction J1 is a junction of iron and copper – two dissimilar metals – which will generate a voltage related to temperature. Note that junction J2, which is necessary for the simple fact that we must somehow connect our copper-wired voltmeter to the iron wire, is also a dissimilar-metal junction which will also generate a voltage related to temperature. Further note how the polarity of junction J2 stands opposed to the polarity of junction J1 (iron = positive ; copper = negative). A third junction (J3) also exists between wires, but it is of no consequence because it is a junction of two identical metals which does not generate a temperature-dependent voltage at all.

The presence of this second voltage-generating junction (J2) helps explain why the voltmeter registers 0 volts when the entire system is at room temperature: any voltage generated by the iron- copper junctions will be equal in magnitude and opposite in polarity, resulting in a net (series-total) voltage of zero. Only when the two junctions J1 and J2 are at different temperatures will the voltmeter register any voltage at all.

We may express this relationship mathematically as follows:  Vmeter = VJ1 − VJ2

With the measurement (J1) and reference (J2) junction voltages opposed to each other, the voltmeter only “sees” the difference between these two voltages.

Thus, thermocouple systems are fundamentally differential temperature sensors. That is, they provide an electrical output proportional to the difference in temperature between two different points. For this reason, the wire junction we use to measure the temperature of interest is called the measurement junction while the other junction (which we cannot eliminate from the circuit) is called the reference junction (or the cold junction, because it is typically at a cooler temperature than the process measurement junction).

For more information on this subject, contact Duro-Sense, Inc. by visiting https://duro-sense.com or by calling 310-533-6877.

Reprinted from "Lessons In Industrial Instrumentation" by Tony R. Kuphaldt – under the terms and conditions of the Creative Commons Attribution 4.0 International Public License.

Friday, April 27, 2018

Thermocouple Junction Configurations

Thermocouple JunctionThermocouples are simple devices made up of several key components: thermocouple wire, electrical
insulation, and the a welded wire sensing junction. Many thermocouple designs also include a stainless steel sheath that protects the thermocouple from vibration, shock, and corrosion.

A thermocouple has three variations of sensing tip (or junction):
  1. Exposed junction, where the exposed wire tips and welded bead have no covering or protection.
  2. Grounded junction, where the welded bead is in physical contact with the thermocouple's sheath.
  3. Ungrounded junction, where the tip is inside the thermocouple sheath, but is electrical (and somewhat thermally) insulated from the sheath (no sheath contact).
Exposed junction thermocouples respond to temperature change quickly and are less costly, but their signals are susceptible erratic reading caused by induced or conducted electrical noise. Because there is no sheath, they are also prone to mechanical damage and ambient contamination.

Grounded junction thermocouples provide fast response and are mechanically more robust, with a metallic sheath that protects the thermocouple both mechanically and from contaminants. But because their sensing tip is in contact with the external sheath, their signal still can be affected by externally induced or conducted electrical noise.

Ungrounded thermocouples, like grounded, are protected mechanically and from ambient contaminants by their sheath. However, their sensing junctions are kept separate from their metallic sheath, isolating the junction from external electrical  interference. This separation does come at a small cost in temperature sensing responsiveness though.

For safety, precision, and optimum performance, always talk to an applications specialist when applying temperature sensors. A short phone call can prevent major headaches and lost time in  troubleshooting a misapplied thermocouple.

Saturday, April 14, 2018

Thermocouples and RTDs Used in Power Plants

Thermocouple and RTD Used in Power Plants
The majority of temperature measuring in a electrical generating plant are done with RTDs (resistance temperature detectors) and thermocouples (T/Cs).

RTD's are devices that produce a measurable resistance change with temperature change, while thermocouples produce a mV signal change in response to temperature change.

RTD's are constructed of a a thin conductor (nickel, platinum, copper) wrapped around a glass or ceramic bobbin, inserted into a protective sheath, and backfilled with an electrically inert, but thermally conductive, material.

Power plants historically use 100-ohm platinum, 100-ohm nickel, 120-ohm nickel, and 10-ohm copper RTDs. While providing excellent accuracy and long term stability, RTDs are prone to mechanical shock and vibration found in a generating facility. They are more expensive than thermocouples and application temperatures are generally limited to around up to 1110°F. One very attractive feature for RTDs are their inherent electrical noise immunity, a significant advantage over thermocouples. Finally, common, inexpensive instrument wire is used for connecting the RTD to the measuring instrumentation.

A thermocouple consists of two wires, made of dissimilar alloys, joined together at each end. One junction is designated the hot junction, the other junction is designated as the cold (or reference junction). When the hot junction experiences a change in temperature, a voltage is generated that is proportional to the difference in temperature between the hot and cold junctions. 

T/Cs are be made of different combinations of alloys and "calibrations" for use at various temperature ranges. The most common thermocouples for the power generation industry applications under 1800 °F are type are J, K and N ; for applications over 1800 °F,  types R and S are common. Aside from the obvious higher temperature capability, thermocouples provide faster response and greater shock and vibration endurance. However, thermocouples, due to the minuter signals the produce, are more susceptible to conducted and radiated electrical noise.  Another concern with thermocouples are their degradation over time when used at elevated temperatures and are therefore less stable than RTDs. One final issue is the need to run costly thermocouple extension wire of the same type as the thermocouple between sensor and measuring instrument.

When in doubt about which sensor is best to apply in a power plant application, contact an application expert who will help you choose the ideal sensor for your requirements.

https://duro-sense.com
Ph: 310-533-6877




Monday, March 26, 2018

The 3 Most Common Temperature Sensors: Thermocouples, RTD's and Thermistors

This post explains the basic operation of the three most common temperature sensing elements - thermocouples, RTD's and thermistors.

Thermocouple
Thermocouple (image courtesy of Duro-Sense)
A thermocouple is a temperature sensor that produces a micro-voltage from a phenomena called the Seebeck Effect. In simple terms, when the junction of two different (dissimilar) metals varies in temperature from a second junction (called the reference junction), a voltage is produced. When the reference junction temperature is known and maintained, the voltage produced by the sensing junction can be measured and directly applied to the change in the sensing junctions' temperature.

Thermocouples are widely used for industrial and commercial temperate control because they are inexpensive, fairly accurate, have a fairly linear temperature-to-signal output curve, come in many “types” (different metal alloys) for many different temperature ranges, and are easily interchangeable. They require no external power to work and can be used in continuous temperature measurement applications from -185 Deg. Celsius (Type T) up to 1700 Deg. Celsius (Type B).

Common application for thermocouples are industrial processes, the plastics industry, kilns, boilers, steel making, power generation, gas turbine exhaust and diesel engines, They also have many consumer uses such as temperature sensors in thermostats and flame sensors, and for consumer cooking and heating equipment.

resistance temperature detectors
Wire-wound RTD (image courtesy of Wikipedia)
RTD’s (resistance temperature detectors), are temperature sensors that measure a change in resistance as the temperature of the RTD changes. They are normally designed as a fine wire coiled around a bobbin (made of glass or ceramic), and inserted into a protective sheath. The can also be manufactured as a thin-film element with the pure metal deposited on a ceramic base much like a circuit on a circuit board.

The RTD wire is usually a pure metal such as platinum, nickel or copper because these metals have a predictable change in resistance as the temperature changes. RTD’s offer considerably higher accuracy and repeatability than thermocouples and can be used up to 600 Deg. Celsius. They are most often used in biomedical applications, semiconductor processing and industrial applications where accuracy is important. Because they are made of pure metals, they tend to more costly than thermocouples. RTD’s do need to be supplied an excitation voltage from the control circuitry as well.

Thermistor
Thermistor (image courtesy of Wikipedia)
The third most common temperature sensor is the thermistor. Thermistors work similarly to RTD’s in that they are a resistance measuring device, but instead of using pure metal, thermistors use a very inexpensive polymer or ceramic material as the element. The practical application difference between thermistors and RTD’s is the resistance curve of thermistors is very non-linear, making them useful only over a narrow temperature range.

Thermistors however are very inexpensive and have a very fast response. They also come in two varieties, positive temperature coefficient (PTC - resistance increases with increasing temperature), and negative temperature coefficient (NTC - resistance decreases with increasing temperature). Thermistors are used widely in monitoring temperature of circuit boards, digital thermostats, food processing, and consumer appliances.

For more information, contact Duro-Sense by calling 310-533-6877 or visit https://duro-sense.com.

Tuesday, March 20, 2018

What is the Difference Between Thermocouple Wire and Thermocouple Extension Wire?

Thermocouple Wire
Thermocouple Wire
Insulated thermocouple wire is single pair wire that can be made into a thermocouple. More specifically, it is the wire from the sensing junction, to the point of cold junction compensation. Thermocouple wire is made from two dissimilar metals conductors that are joined (welded) together at the sensing end. Different metal wires are used for the various types of  thermocouple types (J, K, T, E, etc). These dissimilar metals produce a millivolt electrical signal at the cold junction that is proportional to the change in temperature at the sensing end.  Thermocouple wire has two grades; standard and Special Limits of Error (SLE). Special Limits of Error wire is made of the same metals as standard wire, but uses a higher grade with increased accuracy and higher expense than standard thermocouple wire.

Thermocouple extension wire
Thermocouple extension wire.
Thermocouple wire is almost always insulated. Insulation varies from low temp (Nylon, FEP Teflon, TFE Teflon, PFA Teflon, Kapton) to high temp (fiberglass, Hi-Temp fiberglass, Refrasil, Ceramic Fiber).  Thermocouple wire is typically sold in 1000' spools, but can be sold in small quantities as well.

Thermocouple extension wire is a single pair wire that cannot be made into a thermocouple, but is used to carry the signal from a thermocouple to the recorder, controller, or instrument reading the signal. Extension grade wire is used to carry a signal representing the higher temperature seen by the sensing location, but extension wire itself cannot be generally exposed to those higher temperatures. Extension wire cannot be used to make a thermocouple, but thermocouple wire can be used as extension wire. Insulation is typically PVC, but other option are available.

Multi-pair extension wire is simply more than a single pair in the same jacket.  It is extension only and is usually available in 2,4,6,8,12,16,24 pairs. It is used primarily when a contractor has to run multiple runs of wire. It allows them to run one piece of wire rather than multiple individual runs.

For more information on all varieties of thermocouple wire, contact Duro-Sense by calling 310-533-6877 or visiting https://duro-sense.com.

Wednesday, February 28, 2018

Duro-Sense Sheath-Pak Mineral Insulated Thermocouples

Duro-Sense Sheath-Pak mineral insulated thermocouples are rugged, high temperature sensors made from a drawn tube filled with magnesium oxide and the thermocouple conductor wire.

See the document below for a quick review of these products, or download the Sheath-Pak Mineral Insulated Thermocouple PDF from this link.




Thursday, February 22, 2018

Choice of the Thermocouple Materials

Thermocouple Materials
Of the approximately 300 different types of temperature measuring thermocouples that have been identified and studied, only a few types, having the more favorable characteristics, are in general use. There are eight types of thermocouples that have been standardized, because they are the ones most commonly used industrially. In the United States each type is identified by a letter. This practice was originated by the Instrument Society of America (ISA) and adopted in 1964 as an American Standard to eliminate the use of proprietary names. The standards of the American National Standards Institute (ANSI-MC96.1, 1982) and the American Society for Testing and Materials (ASTM 230-87) utilize the reference tables from National Institute of Standards and Technology Monograph 125 as the basis for standardization. As noted in the ANSI and ASTM standards, the letter designations actually identify the tables and may be applied to any thermocouple that has a temperature-emf relationship agreeing within the tolerances specified in the standards with that of the table, regardless of the composition of the thermocouple. Substantial variations in composition for a given letter type do occur, particularly for types J, K, and E.
  • Type B = platinum- 30% rhodium/platinum-6% rhodium - 0 to 1820°C *
  • Type E = nickel-chromium alloy/a copper-nickel alloy -270 to 1000°C*
  • Type J = iron/another slightly different copper-nickel alloy -210 to 1200°C*
  • Type K = nickel - chromium alloy/nickel - aluminum alloy -270 to 1372°C
  • Type N = nickel-chromium-silicon alloy nickel-silicon alloy -270 to 1300°C*
  • Type R = platinum- 13% rhodium/platinum -50 to 1768°C*
  • Type S = platinum- 10% rhodium/platinum -50 to 1768°C*
  • Type T = copper/a copper-nickel alloy -270 to 400°C*

* temperature range as per NIST Table I: Thermocouple Types Definitions.

Certain combinations of alloys, such as Type J and K, have become popular as industry standards. Thermocouple type selection is driven by cost, availability, melting point, chemical properties, stability, and output. Different type thermocouples are best suited for different uses/applications. Thermocouple types are usually selected on the basis of the temperature range and accuracy needed. Other selection criteria include the chemical inertness of the thermocouple material and whether it is magnetic or not. 

For more information about thermocouples, contact Duro-Sense by calling 310-533-6877 or visiting https://duro-sense.com.

Tuesday, February 13, 2018

Thermocouple Selection Criteria

Thermocouple Selection
Thermocouple shape, assorted
hardware, lead wire insulation
and sheath material are all variable. 
It would be difficult to chart a career course in the industrial process control field without being exposed to thermocouples. They are the ubiquitous basic temperature measuring tools with which all process engineers and operators should be familiar. Knowing how thermocouples work, how to test them, is essential. Sooner or later, though, you may be in charge of selecting a thermocouple for a new application. With no existing part in place for you to copy, what are the selection criteria you should consider for your process?

Thermocouple sensor assemblies are available with almost countless feature combinations that empower vendors to provide a product for every application, but make specifying a complete unit for your application quite a task. Let's wade through some of the options available and see what kind of impact each may have on temperature measurement performance.

Thermocouple Selection
Thermocouple with terminal
block and no head.
Thermocouple Type: Thermocouples are created using two dissimilar metals. Various metal combinations produce differing temperature ranges and accuracy. Types have standard metal combinations and are designated with capital letters, such as T, J, and K. Generally, avoid selecting a type that exhibits your anticipated measurements near the extremes for the type. Accuracy varies among thermocouple types, so make sure the accuracy of the selected type will be suitable.

NIST Traceability: This may be required for your application. The finished thermocouple assembly is tested and compared to a known standard. The error value between the thermocouple shipped to you and the standard are recorded  and certified. The certified sensor assembly will be specially tagged for reference to the standard.

Junction Type: If your sensor will be contained within a tube or sheath, the manner in which the actual sensor junction is arranged is important. The junction can be grounded to the sheath, electrically insulated from the sheath (ungrounded), or protruded from the sheath (exposed). If your process environment may subject the sensor assembly to stray voltages (EMF), it may be wise to stay away from a grounded junction, even though it provides fast response to a change in temperature. Exposed junctions provide very quick response, but are subjected to potential damage or corrosion from surrounding elements. The ungrounded junction provides protection within the enclosing sheath, with a slower response time than either of the other two junction types. When using ungrounded junctions, keep the mass and diameter of the sheath as small as might be practical to avoid overdamping the sensor response.

Probe Sheath Material: This applies to assemblies installed in a tube or sheath which houses and protects the sensor junction and may provide some means of mounting. Material selections include a variety of stainless steel types, polymers, and metals with coatings of corrosion resistant material to suit many applications. Make sure the sheath material, including any coatings, will withstand the anticipated temperature exposure range.
Thermocouple Selection
Thermocouple with handle and
sharpened end for piercing.

Probe Configuration: Sheath tube diameter and length can be customized, along with provisions for bends in the tube. Remember that as you increase the mass around the junction, or increase the distance of the junction from the point of measurement, the response time will tend to increase.

Fittings and Terminations: There are innumerable possibilities for mounting fittings and wiring terminations. Give consideration to ease of access for service. How will the assembly be replaced if it fails? Are vibration, moisture, or other environmental factors a concern? What type of cable or lead wires would be best suited for the application?

Thermocouple Selection
Mounting hardware is very importamt
in thermocouple selection.
Your options are so numerous, it is advisable to consult a manufacturer's application engineer for assistance in specifying the right configuration for your application. Their product knowledge and application experience, combined with your understanding of the process requirements, will produce a positive outcome in the selection procedure.

Duro-Sense Corporation
https://duro-sense.com
310-533-6877

Friday, January 26, 2018

Temperature Sensor Basics: Thermocouples

Industrial style thermocouple
Industrial style thermocouple
(Duro-Sense)
Industrial thermocouples are used for a very broad range of temperature sensing applications. They are inexpensive, accurate, and can be fabricated in many forms to meet the requirements of the process. They operate on the "Seebeck Effect" which is the phenomena of dissimilar metal conductors producing a measurable voltage difference between two substances.

Thermocouples are used widely in industrial processes in industries such as power generation, primary metals, pulp and paper, petro-chemical, and OEM equipment. They can be fabricated in protective wells, and can be housed in general purpose, water-tight, or explosion-proof housings.

Thermocouple types - such a type J, type K, type R, and type S - refer to the alloy combinations used for the conductors and are based on standardized color designations.

The following video provides a basic visual understanding of thermocouple wire, how a T/C junction is determined, and also discusses thermocouple connectors, polarity and some aspects of construction (such as grounded vs. ungrounded vs. open tip).

Wednesday, January 10, 2018

Get to Know Duro-Sense

Here's a short video to learn more about Duro-Sense Corporation. Hope you enjoy.

Tuesday, January 9, 2018

Thermocouple Basics

K thermocouple diagram
Type K thermocouple diagram
A thermocouple is a temperature sensor that produces a micro-voltage from a phenomena called the Seebeck Effect. In simple terms, when the junction of two different (dissimilar) metals varies in temperature from a second junction (called the reference junction), a voltage is produced. When the reference junction temperature is known and maintained, the voltage produced by the sensing junction can be measured and directly applied to the change in the sensing junctions' temperature.

Thermocouples are widely used for industrial and commercial temperate control because they are inexpensive, fairly accurate, have a fairly linear temperature-to-signal output curve, come in many “types” (different metal alloys) for many different temperature ranges, and are easily interchangeable. They require no external power to work and can be used in continuous temperature measurement applications from -185 Deg. Celsius (Type T) up to 1700 Deg. Celsius (Type B).

Welcome to the Duro-Sense Blog

Welcome! We hope (over time) you find this blog interesting to visit and it becomes a trusted resource for all-things-temperature-measurement.

We plan on weekly educational and informative blog posts about innovative temperature sensor solutions, insight to how sensors work, and new products that solve tough engineering challenges.

Specific products we'll be discussing are:
Please come back often!