A blog providing information about industrial temperature measurement, specifically in the areas of temperature sensors. The posts will contain educational information about thermocouples, RTDs, and other common types of temperature sensors. The application of these sensors will focus on aerospace, aircraft, research and development, medical, chemical, plastics processing, and power generation industries. For more, visit Duro-Sense.com or call 310-533-6877.
Saturday, December 10, 2022
What's The Difference Between Thermocouples and RTDs?
Thursday, September 29, 2022
Wire-wound and Thin Film Resistance Temperature Detectors
Thursday, August 18, 2022
Industrial Uses of Resistance Temperature Detectors (RTDs) Explained
Introduction: What is an RTD?
RTDs are sensors that measure the temperature of a material and provide an indication of its resistance to thermal changes.
An RTD is a sensor that measures the temperature of a material and provides an indication of its resistance to thermal changes. RTDs can be manufactured as either a wire or as a thin film on silicon.
The first RTD was developed in 1887 by German inventor Hermann von Helmholtz.
RTDs are typically used in industrial applications such as power plants, refineries, paper mills, and steel mills where they monitor temperatures of process fluids, gases, or equipment surfaces.
RTDs have also been used for years in home appliances like ovens and furnaces to control the temperature inside them.
What is a Typical Industrial Use of RTDs?
RTDs are used in industrial settings to measure the temperature of liquids and gases. This is done by measuring the resistance of a metal element which changes with temperature. RTDs have many applications in industry, such as controlling the temperature of devices, monitoring equipment, and testing for leaks.
Industrial use of RTDs can be found in a wide range of industries. For example, they are used to monitor the temperature of food processing plants and oil refineries. They are also used for quality control purposes in semiconductor manufacturing plants and petrochemical factories.
Other Industrial Uses of Resistance Temperature Detectors
Industrial use of RTDs is extremely common in the manufacturing industry. They are used in industrial processes to measure and control temperature, as well as to detect hot spots and cool spots.
RTDs are also used in many engineering applications such as process control, instrumentation, and automation for a variety of purposes.
Duro-Sense Corporation
310-533-6877
https://duro-sense.com
Saturday, July 30, 2022
Industry Leading Delivery Times for Thermocouples and RTDs
Customers dislike having to wait. Customer happiness and loyalty are directly related to how soon items are delivered.
Wednesday, April 6, 2022
Duro-Sense 100 OHM Platinum RTD Temperature Sensors
RTDs (Resistance Temperature Detectors) are temperature detecting devices that vary their resistance value when surrounding temperature changes. RTD sensing elements use well-known materials that change resistance in a predictable and repeatable manner. Their popularity and general use are outcomes of the RTD's predictability and stability.
The most common type and material of RTD is the 100-ohm platinum sensor. Its use is ubiquitous in the laboratory and industrial process applications going back many decades. The precision, reproducibility, and stability of 100-ohm platinum RTDs (PT100) are well known.
For the most part, resistance temperature detectors (RTDs) fall into two main categories. Thin-film elements are one form of RTD, and wire-wound elements are the other. Each type provides advantages in certain situations and purposes. The more common design, wire-wound, is a length of tightly coiled wire wrapped around a ceramic or glass bobbin. Because the wire and wrapping are delicate, it is usually enclosed in an encased metallic tube to protect them from stress and vibration.
The 100-ohm platinum RTD provides accurate temperature readings with excellent stability and repeatability. They are also very resistant to electrical noise, making them ideal for temperature monitoring in industrial facilities near motors, generators, and high voltage equipment.
The American and European (known as the DIN or IEC standard) 100-ohm platinum RTD standards are the same, with the IEC standard considered the default for PT100. According to the IEC751 standard, the RTD must have:
- The electrical resistance of 100.00 O at 0°C
- A TCR (temperature coefficient of resistance) of 0.00385 O/O/°C between 0 and 100°C.
Because resistance is used to measure temperature in 100-ohm platinum RTDs, the lead wires, connections, and measurement devices contribute extra resistance, requiring external compensation to offset the error. A solution is found by inserting a third or fourth lead wire inversely proportional to the external resistances.
Duro-Sense Corporation
310-533-6877
https://duro-sense.com
Monday, December 21, 2020
Fast Selection Criteria between Thermocouples and RTDs
Both RTD and thermocouple probes monitor temperature, but which one is right for your application?
What temperature range are you trying to monitor?
Generally, if the temperature is above a hundred and fifty degrees Celsius, a thermocouple would be used. For anything below a hundred and fifty degrees Celsius, choose an RTD.
What is the required sensor accuracy?
RTDs provide more accurate readings with repeatable results. Choose RTDs when temperature accuracy and repeatability are critical.
What is the purchase budget?
Thermocouples can be up to three times less expensive than RTD sensors, making thermocouples the right choice when purchasing large quantities or requirements on tight budgets.
Use these three criteria to narrow down your selection process. There are many other differences between thermocouples and RTDs you need to understand before selection and application.
Always consult a temperature sensor application expert before installing or specifying a thermocouple or RTD where failure can cause harm or personal injury.
Wednesday, November 18, 2020
100-Ohm Platinum RTD Temperature Sensors
RTDs (short for Resistance Temperature Detectors) are temperature sensing devices that change resistance value as its temperature changes. The most popular RTD is the 100-ohm platinum sensor, used for many years to measure temperature in laboratory and industrial process applications. 100-ohm platinum RTDs (PT100) have a reputation for accuracy, repeatability, and stability.
Most RTD element designs include a length of finely coiled wire wound around a ceramic or glass bobbin. The inherent system is fragile, so it is typically placed inside a sheathed metallic tube to protect from shock and vibration. RTD sensing elements are made from a material with a very predictable and repeatable change in resistance. This predictability and stability is the basis for its widespread application.
The 100-ohm platinum RTD provides accurate temperature readings with reasonable accuracy, excellent stability, and repeatability. They are also significantly immune to generated electrical noise, and as such, they are well suited for temperature measurement in industrial plants, near motors, generators, and high voltage equipment.
There are two 100-ohm platinum RTD standards, the American and the European (known as the DIN or IEC standard), with the IEC standard considered the default for PT100. The IEC751 standard requires the RTD to have an electrical resistance of 100.00 O at 0°C and a TCR (temperature coefficient of resistance) of 0.00385 O/O/°C between 0 and 100°C.
Because 100-ohm platinum RTDs use resistance to measure temperature, the lead wires, connectors, and measuring devices introduce additional resistance. These must be compensated for by configuring the RTD circuit to null out these outside resistances by incorporating a third or fourth lead wire to offset the introduced error.
For more information about 100-ohm platinum RTD temperature sensors, contact Duro-Sense Corporation. Call them at 310-533-6877 or visit their website at https://duro-sense.com.
Wednesday, October 28, 2020
Temperature Sensors Used for Power Generation
In an electrical generating plant, most temperature measurements are performed with RTDs (resistance temperature detectors) and thermocouples (T/Cs).
RTD's are sensors that produce a measurable change in electrical resistance, while thermocouples have a change in mV signal in response to temperature change.
RTD's consist of a thin conductor (nickel, platinum, copper) wrapped around a glass or ceramic bobbin, placed into a protective sheath, and backfilled with an electrically inert material but thermally conductive.
Power plants use 100-ohm platinum, 100-ohm nickel, 120-ohm nickel, and 10-ohm copper RTDs. Though offering excellent accuracy and long-term reliability, RTDs are vulnerable to mechanical shock and vibration in a generating plant. They are more costly than thermocouples and are generally limited to about 1110 ° F. A very appealing feature for RTDs is their electrical noise immunity, a significant advantage over thermocouples. Finally, inexpensive instrument wire is all that is required to connect the RTD to the measuring instrumentation.
A thermocouple consists of two wires made of dissimilar alloys, joined at both ends. One junction is coined the "hot junction," the other is the "cold junction" (or reference junction). When the hot junction experiences temperature change, a voltage is produced proportional to the temperature difference between hot and cold junctions.
T/Cs are made of various alloy combinations and "calibrations" for different temperature ranges. Type J, K and N are the most common thermocouples for power generation applications below 1800 ° F; R and S types are common for applications above 1800 ° F. Besides the evident higher temperature capacity, thermocouples have a quicker response and greater endurance to shock and vibration. However, thermocouples are more susceptible to conducted and radiated electrical noise due to the minute signals generated. Another problem with thermocouples is their deterioration over time when used at high temperatures, hence being less stable than RTDs. One final concern is running an expensive thermocouple extension wire of the same type as the sensor-measuring instrument thermocouple.
Duro-Sense Corporation
310-533-6877
https://duro-sense.com
Saturday, May 23, 2020
Resistance Temperature Detector (RTD) Catalog

DOWNLOAD THE DURO-SENSE RTD CATALOG HERE
Thursday, January 30, 2020
Full Duro-Sense Product Catalog Now Available
Duro-Sense Corporation designs and manufactures the finest quality thermocouples, RTDs, and custom temperature assemblies used in a wide variety of industries including aerospace, medical, power generation, food and beverage, pulp & paper, chemical processing, plastics, pharmaceutical, and life science. Duro-Sense products are known throughout these industries for their quality and reliability.
From simple wire and tube assemblies for the plastics industry, to mineral insulated and multipoint thermocouples, to custom sensors for specific applications, Duro-Sense can design, manufacture, and deliver solutions to virtually any temperature related application.
Monday, November 25, 2019
Precision Thermocouples and RTDs for the Most Demanding Applications
Duro-Sense Corporation provides the highest quality thermocouples and RTDs to the aerospace, aviation, offshore drilling, medical, R&D, power generation, alternative energy, process control, primary metals, high-tech and OEM industries.
Contact Duro-Sense by calling 310-533-6877 or visit their web site at https://duro-sense.com.
Monday, September 23, 2019
Three Simple Questions for Choosing Thermocouples or RTDs
What's the best choice for your industrial temperature sensing requirement, a thermocouple or RTD? In industrial installations, both types of sensor can be specified with similar mounting accessories, dimensional specifications, and instrument interfaces. However, there are three criteria you need to consider before choosing between an RTD or thermocouple probe.
First, what is the temperature range you are trying to monitor?
Generally, if the temperature exceeds five hundred degrees Celsius (500 deg C), thermocouples are for you. RTD's are best between -200 and 500 °C, while thermocouples have a range of -180 to 2,320 °C. For anything above 500 Celsius, you should select the appropriate thermocouple calibration for the sensing range you're working in.Second, what type of sensor accuracy do you need?
RTDs are more accurate temperature sensors, offer highly repeatable readings, drift less over time, and are suitable for high precision requirements. Thermocouples are generally less accurate and are subject to drift. Typical thermocouple accuracy is 2 deg. C.Third, how about the budget you're working under?
Thermocouples can be up to three times less expensive than RTD probes, making thermocouples a good choice if high accuracy and repeatability are not critical. One caveat though. Make sure you consider any additional cost incurred with long runs of thermocouple extension wire. For installations requiring dozens or even hundreds of temperature sensors, the significant difference in basic sensor cost is an important consideration.These three criteria are VERY basic, and intended just to point you in the right direction. There are many other differences between thermocouples and RTDs that need to be understood before application. Consult a temperature sensor expert prior to installing or specifying a thermocouple or RTD wherever or whenever failure can cause harm.
Friday, July 26, 2019
Duro-Sense Corporation: Celebrating Our 40th Year in Business
Since 1979, Duro-Sense has grown exponentially in product capability and market experience. The company today continues to succeed by operating under a simple core value – providing customers with superior products, meticulously engineered for their individual requirements.
Thursday, July 11, 2019
Duro-Sense: A Long History of Solving Tough Temperature Sensing Problems

Duro-Sense offers their customers products and services designed to provide outstanding value and cost savings throughout the customer's equipment life span. By integrating the highest quality standards, state-of-the-art machinery, and decades of application experience, Duro-Sense assists customers through:
- Improved product quality
- Optimize asset uptime and performance
- Lower total cost of operation and maintenance
- Increase equipment reliability
- Improve plant and personnel safety
ENGINEERING AND TECHNICAL SERVICES
Technical Analysis — Duro-Sense can identify temperature sensor operational issues that may be constraining output or elevating operating costs, and then recommend laser-focused solutions.
Reliability and Efficiency Services — Duro-Sense lends their decades of hands-on experience to offer practical temperature sensing solutions that improve the performance, efficiency, and reliability of your process control equipment - all while lowering your total cost of ownership.
Loop Design, Integration and Engineering Support — Duro-Sense engineers engage with their customers, providing support for grassroots project planning, system design, or project management requirements.
Equipment Life Cycle Optimization — Through a combination of assessments and technology, Duro-Sense experts help customers benchmark operational performance, define key metrics, and implement precise sensor solutions to achieve long-term operational goals.
Intelligent Product Design — By employing an array of sophisticated products, services, and software that collects, examines and understands data, Duro-Sense helps customers use predictive analytics to take action and improve asset reliability and reduce downtime.
Have a challenging temperature sensing requirement? Call Duro-Sense.
Duro-Sense Corporation
310-533-6877
Friday, May 24, 2019
Quick Comparison of Temperature Sensors
Thermocouples are commonly used because of their simplicity, reliability, and relative low cost. They are self-powered and eliminate the need for a separate sensor power supply. Thermocouples are quite durable when selected for a given application appropriately. Thermocouples can also be used for applications with high temperatures.
Resistance temperature detectors (RTDs) are attractive alternatives to thermocouples when the output is desired to be highly accurate, stable and linear (i.e. just how close the calibration curve looks a straight line). The superior linearity of relative temperature resistance enables simpler signal processing devices for RTDs than thermocouples.
Thermistors are similar to RTD because they're a resistance measurement device, but thermistors use a very cheap polymer or ceramic material as the element in lieu of the use of pure metal.
For more information on any type of industrial or OEM temperature sensor, contact Duro-Sense by calling 310-533-6877 or by visiting https://duro-sense.com.
Monday, March 25, 2019
A Pro and Con Comparison of Thermocouples and RTDs
Thermocouple Advantages
- Inexpensive
- Wide temperature range
- Various types, sizes and application methods
- Remote read back
- Read back electronics can be simple
- Usable in virtually any environment
- Requires cold junction compensation
- Slow response time
- Not as accurate as many other devices without good CJC and calibration
- Susceptible to noise
- Connection cable/wire is expensive compared to copper conductors
- Cable/wire length is limited
- More linear than thermocouples
- Cold junction not an issue
- Special cable/wire not needed
- Cable/wire length can be much longer than TC’s
- Better noise immunity
- More stable over time than thermocouples
- Remote read back
- Usable in virtually any environment
- More expensive than thermocouples
- More delicate than thermocouples unless encased
- Not as wide of temperature range as thermocouples
- Requires more conductors per device
- Read back electronics more complex
Tuesday, March 12, 2019
Theory of RTD Operation

Most commonly used is the platinum 100 ohm RTD because of their stability in air and linearity. Their resistance is 100 ohms @ 0 Deg.C and increases with temperature.

Alpha is ohms per ohm per Deg.C.
The average resistance change per unit of temperature from boiling point to ice point of water:
- Rboiling – Rice point/100deg/100ohms
- 138.5 – 100.0/100/100 = .00385
Tolerance class is the amount an RTD will differ from the standard resistance curve per Deg.C.
- Class A (+/- .15 + .002*t)
- @ temp of 100DegC = +/- .35DegC
When ordering an RTD, a tolerance class will be part of the order, dependent on the application. IEC 751 stipulates that the RTD be marked with their nominal R0 value, their tolerance class, the wiring configuration and the temperature range.
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3-wire configuration |
- Pt100 / A / 3 / -100/+200 = Platinum 100 Ohm / Class A / 3-Wire / -100 to +200 Deg.C
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2-wire configuration |
Another configuration is a two wire RTD with a stand-alone loop. (Probably rarely used today).
Since the RTD is a resistance device, the resistance of the wires used to connect the RTD to the measurement meter introduces errors and must be known. This is the reason a third (or fourth), wire is used.
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3rd wire used to cancel wire error |
Then the meter reads the resistance of one of the common wires, the RTD, and the non-common wire to determine Rtotal
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Meter reading 2 common wires |

Rt = Rtotal – Rwire
Friday, February 15, 2019
Temperature Sensing IS Rocket Science
Duro-Sense Corporation provides the precision temperature sensors to the aerospace, aviation, and space industries. Duro-Sense engineers bring proven solutions to your most difficult problems. Their R&D department is staffed with some of the industry's most qualified people, working in the most modern facilities to help advance the state of the art in temperature measurement.
Monday, January 28, 2019
Where to Mount Industrial Temperature Transmitters?

There are basically three different locations for the mounting of the temperature transmitters:
- In-head mounting - inside the connection head of the temperature sensors.
- Field mounting – close to the temperature sensors.
- Central mounting - in the vicinity of the control room
In-head mounting
The transmitters are mounted directly inside the connection head and are normally replacing the terminal block. This way of mounting normally offers the biggest advantages. It is however necessary to be aware of the environmental influence (mainly the temperature) on the measurement accuracy.Advantages
- Maximum safety in the signal transmission. The amplified signal, e.g. 4- 20 mA, is very insensitive to electrical disturbances being induced along the transmission cable.
- Cost savings for the transmission cables. Only two leads are required if a 2- wire transmitter is used.
- Cost savings for installation. No extra connection points because of the transmitter.
- Cost and space savings. No extra housings or cubicles are needed.
- Field instruments, e.g. indicators, can easily be installed, also at a later stage without redesigning the measuring circuits.
- The ambient temperatures can be out- side the allowed limits for the transmitters.
- The ambient temperature influence on the measuring accuracy has to be considered.
- Extreme vibrations might cause malfunction of the transmitters.
- The location of the temperature sensor can give maintenance problems.
Field mounting
The transmitters are either mounted directly beside the temperature sensors or in the vicinity of the sensors. Often more than one transmitter is mounted in the same field box.This method is more expensive than In-head mounting, but otherwise a good alternative offering most of the advantages of In-head mounting without the disadvantages mentioned above.
Advantages
- High safety in the signal transmission. The main part of the signal transmission is made with an amplified signal.
- No extreme temperatures or vibrations exist. This facilitates accurate and safe measurements.
- Cost savings for transmission cables.
- A wider selection of transmitters is available. DIN rail transmitters can also be used.Field instruments can often be installed easily.
- Maintenance can normally be carried out without problems.
- Higher installation costs compared to In-head mounting.
- Costs and space requirements for transmitter boxes or cubicles.
Central mounting
In this case, the transmitters are placed in the vicinity of the control room or in another central part of the plant They are often mounted inside cubicles, and/or closed rooms. The ambient conditions are normally very good and stable.This method offers the most convenient conditions for maintenance and the best possible environment for the transmitters. There are on the other hand some disadvantages that should be considered.
Advantages
- Convenient conditions for installation, commissioning and maintenance.
- Minimum risk for environmental influences (e.g. temperature influence).
- Reduced safety in the signal transmission. The low-level sensor signal is rather sensitive to electrical disturbances being induced along the trans- mission cable.
- Relatively high costs for cabling. T/C measurements require compensation or extension cables all the way to the transmitters. RTD measurements with high accuracy should be done in 4-wire connection to get rid of the lead resistance influence.
- Costs and space requirements for cubicles or frames.
- Rather complicated and expensive to connect field instruments, e.g. indicators.
For more information on using temperature transmitters, contact Duro-Sense by calling 310-533-6877 or by visiting https://duro-sense.com.