Four channel remote temperature sensor works to -40°C

Called MCP9904, it has advanced features such as resistance error correction as well as beta compensation, the latter to support CPU diodes requiring the BJT/transistor model  – those on 45nm processes, for example.

“Beta compensation eliminates temperature errors caused by low, variable beta transistors common in today’s fine geometry processors,” said Microchip. “The automatic beta detection feature monitors each external diode/transistor and determines the optimum sensor settings for accurate temperature measurements regardless of processor technology. This frees the user from providing unique sensor configurations for each temperature monitoring application.”

Resistance error correction automatically reduces temperature error caused by series resistance allowing greater flexibility in routing thermal diodes, there is a sample-frequency hopping filter, and also automatic diode type detection.

“These enable remote diode temperature measurement up to 100 feet [30m] off-board away from the IC,” said Microchip.

Overall, local accuracy up to ±1°C over -40°C to +65°C is claimed, and remote accuracy of ±1°C to +105°C

The chip has one internal  temperature sensor and will work with up to three external diodes. For fewer channels, the MCP9903 is a similar chip with two external channels, and the MCP9902 has one.

Communication with a host is though SMBus (System Management Bus) or I2C.

For development, there is the ADM00615 evaluation board, whic hlooks like it has the dual-channel MCP9902.

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U.S. Temperature Sensors Market Worth $1.65 Billion by 2018 - Increasingly Used in Communication Industry - Research and Markets

The U.S.temperature sensors market is expected to increase to $1.65 billion by 2018 at a CAGR of 6.91% over the period 2015-2020.

Temperature sensing has been gaining importance, particularly in R&D and industrial settings, giving rise to high demand for temperature sensors. Companies operating in the market have been investing heavily in research and development activities in order to develop and enhance temperature sensor functionality. Increasing adoption of HVAC modules is expected to favorably impact the U.S. industry. Even the technological advancements and reduced prices have resulted in Introduction of new applications in the HVAC space.

Growing demand for consumer electronics such as smartphones, cameras and media players make use of microprocessors, which is expected to boost market growth, as they have temperature sensing ICs. Mandates related to safety in U.S. have acted as a key driver for overall industry growth. Temperature controls are essential for manufacturing, handling and storing of medical equipment and drugs.

They are increasingly used in communication industry with growth in handheld communication devices. Intense competition and significant price cuts may restrain the temperature sensors market over the forecast period. U.S. accounted for about 83% of the North American market in 2015, the largest segment over the forecast period, mainly due to advancements in sensor technologies in the region.

Key Topics Covered:
1. Introduction
2. Key Findings
3. Market Overview & Dynamics
4. Introduction
5. Porter's Five Forces Analysis
6. Market Segmentation
7. Company Profiles
8. Investment Analysis
9. Future Of Temperature Sensors Market

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Non-contact Temperature Sensors Exhibit Increased Penetration into Diverse Applications

This research service provides a perspective on the global infrastructure and buildings market. It focuses on both end-user markets and key sensors used. The most significant trends, drivers, and restraints that impact each have been discussed. The research service focuses on both existing and forecasted revenues for the segments and total markets.

This research service also provides a detailed snapshot of the market's competitive landscape and presents a forecast of revenue growth. Special focus is given to trends related to two key vertical markets, applications, distribution, technology, and value chain. As these sensors are highly technical, a detailed discussion on various technological aspects has been included in this deliverable.

Key Findings:

• An optical pyrometer determines the temperature of a very hot object by the color of the visible light it gives off. A radiation pyrometer determines the temperature of an object from the radiation (IR) given off by the object.
• Although the term pyrometer is generally considered to apply to instruments that measure high temperatures only, some pyrometers are designed to measure low temperatures.

Key Topics Covered:

1. Executive Summary

2. Market Overview

3. Market Dynamics-Key Drivers and Restraints

4. Forecasts and Key Technology Trends-Total Temperature Sensors Market

5. Market Share Analysis-Total Temperature Sensors Market

6. IR Temperature Sensors Segment

7. Forecasts and Trends-IR Temperature Sensors Segment

8. Market Share and Product Profiles of Key Companies by Product Type-IR Temperature Sensors Segment

9. Pyrometers Segment

10. Emerging Markets and Opportunities Analysis

11. Temperature Sensors Used Differently

12. Cryogenic Temperature Sensors-Product Types, Applications, and Key Companies

13. Purchase Process Analysis of Temperature Sensors

14. The Last Word

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N.A. Leads Temperature Sensors Market Growth of 4.8% CAGR to 2020

The increasing demand from industrial end users would drive global temperature sensors market growth, wherein thermocouple-based temperature sensors are to gain maximum traction during the forecast period. North America is expected to lead the global temperature sensors market during the forecast period (2016-2022).

Complete report on global temperature sensors market spread across 202 pages, profiling 15 companies and supported with 79 tables and 107 figures is now available.

The temperature sensors market is expected to grow from USD 5.13 billion in 2016 to USD 6.79 billion by 2022, at estimated CAGR of 4.8% between 2016 and 2022. The temperature sensors market is primarily driven by factors such as high demand for temperature sensors among industrial end users, growing concerns toward security and surveillance, robust demand for consumer electronics products, developing automotive industry in emerging markets, and government initiatives toward environment & safety norms.

The market for thermocouple-based temperature sensors holds the largest share of this market. Furthermore, owing to the increasing demand for measuring and controlling sensors in industrial sectors on a global basis, temperature sensors devices are expected to gain traction and grow at a stable growth rate during the forecast period. The temperature sensors is expected to have a high demand from discrete industry end users such as semiconductors, automotive, and healthcare segment among others during the forecast period.

The North American market is expected to hold the major market share between 2016 and 2022 owing to the growing demand for smart homes and in-home weather stations in the U.S., rising usage of temperature sensor products by scientific research institutions for the study of environmental changes across North America, and the presence of major temperature sensors manufacturers in the region. The APAC market is expected to grow at the highest CAGR between 2016 and 2022.

The report includes company profiles of major players, recent activities in the market, new product launches, mergers & acquisitions, collaborations and partnerships, and SWOT analysis. Some of the companies profiled in this report are Texas Instruments Incorporated (U.S.), Analog Devices, Inc. (U.S.), ABB Ltd. (Switzerland), Honeywell International Inc. (U.S.), Maxim Integrated Products Inc. (U.S.), Siemens AG (Germany), Danaher Corporation (U.S.), Kongsberg Gruppen (Norway), TE Connectivity Ltd. (U.S.), Emerson Electric Company (U.S.), Panasonic Corporation (Japan), General Electric Company (U.S.), STMicroelectronics N.V. (Switzerland), Microchip Technology Incorporated (U.S.) and NXP Semiconductors N.V. (Netherlands). Order a copy of Temperature Sensors Market by Type (Thermistor, IC, RTD, Thermocouple, & Others), End User (Process Industry (Chemical, Oil & Gas, Power and Others) & Discrete Industry (Semiconductors, Automotive and Others)) and Geography - Global Forecast to 2022 research report.

This report segments the temperature sensors market comprehensively and provides the closest approximations of the revenue numbers for the overall market and the sub segments across the different verticals, segments, and regions. The report would help stakeholders to understand the pulse of the market and provides them information on key market drivers, restraints, challenges, and opportunities. This report would help stakeholders to better understand the competitor and gain more insights to enhance their position in the business. The competitive landscape section includes competitor ecosystem, new product developments, partnerships, and mergers and acquisitions.

On a related note, another research on Light Sensors Market Global Forecast to 2022 says, the global light sensors market is estimated to grow at a CAGR of 9.3% between 2016 and 2022and is expected to reach USD 2.14 billion by 2022. Automotive applications are to gain maximum traction during the forecast period. Asia-Pacific expected to grow at a high CAGR by 2022. Companies like ams AG (Germany), Avago Technologies Inc. (Singapore), Elan Microelectronics Corp. (Taiwan), Everlight Electronics Co. (Taiwan), Heptagon (Singapore), Maxim Integrated Products Inc. (U.S.), ROHM Co., Ltd. (Japan), Sharp Corporation (Japan), Sitronix Technology Corp. (Taiwan), STMicroelectronics NV (Switzerland), Samsung Electronics Co., Ltd. (South Korea), and Vishay Intertechnology, Inc. have been profiled in this 156 pages research report available.


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List of temperature sensors

Mechanical temperature sensors

Thermometer

Therm

Electrical temperature sensors

Thermistor- Thermistors are thermally sensitive resistors whose prime function is to exhibit a large, predictable and precise change in electrical resistance when subjected to a corresponding change in body temperature. Negative Temperature Coefficient (NTC) thermistors exhibit a decrease in electrical resistance when subjected to an increase in body temperature and Positive Temperature Coefficient (PTC) thermistors exhibit an increase in electrical resistance when subjected to an increase in body temperature.

Thermocouple

Resistance thermometer

Silicon bandgap temperature sensor

Integrated circuit sensors

Manufacturers

Analog Devices

Microchip

Texas Instruments

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Temperature sensors are improving, but select carefully

From thermocouples and thermistors to resistance-temperature-detectors (RTDs), temperature sensors are varied and ubiquitous, but it would be wise not to take them for granted. Each type comes with its own set of inherent pros and cons in terms of cost, reliability, linearity, and ease of use. In this feature we will take you through some classics, while also updating you on the state of the art, how to make best of them, and a good example or two of temperature sensor and silicon integration. 

Temperature sensors really are everywhere: used in automotive, infrastructure, industrial, military/aerospace, consumer electronics, medical, transportation, power, process control, petro-chemical, and geo-physical, agriculture, and communications applications. When used in combination with other sensors like strain and pressure sensors, they’re making the applications they serve more intelligent, safer, and more reliable. In many systems, temperature monitoring and control is fundamental. 

By far, the biggest challenge designers face when using temperature sensors is how and where the sensor is placed with respect to the object or environment being measured (the measurand). Even the type of package and how it is mounted can make a difference between satisfactory and unsatisfactory measurements. With signal levels so low, losses in the connecting wires are but one of the issues to be overcome, but more on that in upcoming features.

In the meantime, one popular type of temperature sensor is the thermocouple, and for good reason. No other temperature sensor can rival it in terms of its wide-ranging temperature sensing ability of minus hundreds of °C to nearly 2000°C. It is also rugged and can withstand harsh environments.

But it’s also highly non-linear and requires the use of significant linearization algorithms. It also produces very small output voltages of tens of µV/°C, requiring the use of analog amplification, and is susceptible to noise which means signal conditioning is required. And it is fairly accurate provided that accurate correct cold-junction compensation (CJC) and signal conditioning is provided. Experts agree that the signal-conditioning aspect of a thermocouple is a major challenge for temperature sensor users. 

Fortunately, there are many inexpensive monolithic ICs on the market that help, like the Analog Devices ADT7420/ADT7320 (I2C/SPI outputs). It allows thermocouple cold-junction compensation with accuracy within ±0.25°C (Figure 1). Together with Analog Devices’ AD849x series of precision amplifiers, it provides convenient analog CJC for modern thermocouple sensor types.

Figure 1 Analog Devices’ ADT7420/7320 16-bit digital temperature sensor with I2C/SPI outputs allows thermocouple cold-junction compensation with accuracy within ±0.25°C. (Source: Analog Devices)

The ADT7320/7420 16-bit sensors also have the added advantage of not requiring calibration. Recommended for new designs by ADI, start with the EVAL-ADT7420 evaluation board. 

Thermistors: Low cost, but keep one eye on current

Another popular temperature sensor type is the thermistor, not least because of it’s very low cost (a few cents in large quantities). This thin-film sensor is quite small (a bead of about 4 mm in diameter with two leads) and it suits applications like over- and under-voltage shutdown instrumentation. It is highly sensitive and accurate, rugged, and flexible enough to be fitted into a variety of packages.

But it does have one problem. It is a self-heating device so proper care must be taken to limit the current being sensed to a low-enough value to minimize this challenge. It is also susceptible to moisture failure, though modern glass-encapsulated thermistors can be purchased to handle this problem, adding extra cost, of course. And software is needed to handle a thermistor’s inherent non-linearity.

Thermistors come in positive temperature coefficient (PTC) and negative temperature coefficient (NTC) versions that increase and decrease their resistances in response to increasing and decreasing temperatures, respectively.  

RTDs: Stable and linear, but slow response

For a higher price, a resistance-temperature detector (RTD) offers the best linearity and stability over a reasonably wide temperature range of about −250°C to 850°C, which is second only to a thermocouple. An RTD consists of a deposited film of copper or platinum. Its resistance increases with increasing temperatures in a known and repeatable manner, with excellent accuracy levels. RTDs like the F2020 series from Omega Engineering offer designers a flat 2×2 mm factor (Figure 2).

Figure 2 An RTD like this Omega Engineering F2020 series is a good choice for linear and stable temperature measurements with excellent accuracy. (Source: Omega Engineering)

It is made on OmegaFilm platinum material and comes in 100-Ω, 500-Ω, and 1-k Ω versions, can operate over a −50°C to 500°C range, and comes with platinum-coated nickel wires.

RTD users beware! An RTD’s response time is very slow (in the few seconds range). It is also highly susceptible to lead resistance effects thus requiring lead-wire compensation, limiting its use in 3-wire and 4-wire configurations. (2-wire configurations cannot compensate for lead-wire resistances).

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Temperature Sensors Market Is Expected To Reach USD 6.13 Billion By 2020

The global Temperature Sensors Market is expected to reach USD 6.13 billion by 2020. Increasing global demand for smarter consumer electronics and automobiles is expected to favor market growth over the forecast period. Temperature sensors are increasingly used in smartphones and other consumer electronics to monitor their temperature and enhance performance.

Basic temperature sensors include resistive temperature devices (RTD), thermocouples, liquid expansion devices, silicon diodes, infrared sensors etc. Additionally, fusion of communication, computing and sensing is expected to drive the MEMS market, which is expected to benefit global temperature sensor demand. Technological advancements and device miniaturization also drive market growth. Need for ensuring safety and favorable regulatory scenario is expected to fuel market growth over the forecast period. However, intense competition and significant price cuts may restrain the temperature sensors market over the forecast period.

Further key findings from the study suggest:
• Consumer electronics and environmental applications are expected to grow at a considerable rate over the forecast period. Temperature sensors are increasingly used standalone or integrated with diverse equipment. This technology is spurred by factors such as low cost and power and wireless connectivity. Introduction of new raw materials such as polymers is expected to lower the weight, size and cost of electronic devices.
• Sensors are used in wide range of applications such as consumer electronics, automotive, process industries etc. owing to easy equipment integration. Temperature sensors are increasing used in automotive applications such as cylinder head temperatures, coolant, and air intake. Therefore, rise in automobile production is expected to favor market demand. Temperature sensors are also used in HVAC, environmental control, food processing, medical devices and chemical handling applications.
• The Asia Pacific temperature sensors market accounted for over 30% of the global demand and is expected to grow at a considerable rate over the next six years. The regional market is expected to be driven by advancements in sensor technology and demand for high-performance sensors that can be fitted into handheld portable devices. China is expected to be the largest contributor to regional market revenue generation over the next six years.
• Key market participants include ABB, Delphi Automotive, Analog Devices Inc., Siemens AG, Freescale Semiconductor, Honeywell International, Texas Instruments, NXP Semiconductors, Panasonic, etc. Honeywell serves various industries including aerospace & defense, medical, transportation, industrial etc. Key players are increasingly moving their manufacturing facilities in countries with economical labor particularly in Asia Pacific to reduce their overall cost. Cost effective and differentiated services are expected to be a critical success factor for the industry participants.

Temperature Sensors Application Outlook (Revenue, USD Million, 2012 - 2020)
• Automotive
• Consumer Electronics
• Environmental
• Healthcare & Medical
• Process Industries

Temperature Sensors Regional Outlook (Revenue, USD Million, 2012 - 2020)
• North America
• S.
• Europe
• Germany
• UK
• Asia Pacific
• China
• Japan
• India
• RoW
• Brazil
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Radio waves power up world's smallest temperature sensor

A team of researchers at Eindhoven University of Technology (TU/e) has come up with what they describe as a very tiny wireless temperature sensor powered in a very special way: from the radio waves that are part of the sensor's wireless network. As such, the sensor does not need even a single wire, nor a battery that would have to be replaced.

The smart buildings of the future will be full of sensors that will respond to the residents' every need, and will be as sustainable as possible. Like heating and lighting that only switches on when someone is in the room. That's only possible if these sensors are wireless and need no batteries, otherwise in a large building you would have to change the batteries every day. This is demonstrated by TU/e researcher Hao Gao who, in his thesis, developed a sensor that measures just 2mm²and weighs 1.6mg, equivalent to a grain of sand.

The present version of the sensor has a range of 2.5cm; the researchers expect to extend this to a metre within a year, and ultimately to 5m. The sensor has a specially developed router, with an antenna that sends radio waves to the sensors to power them. Since this energy transfer is accurately targeted at the sensor, the router consumes very little electricity. And the sensors themselves are made such that their energy consumption is extremely low. The sensor also operates beneath a layer of paint, plaster or concrete. As Peter Baltus, TU/e professor of wireless technology, explained, this makes the sensor easy to incorporate in buildings, for instance by 'painting' it onto the wall with the latex.

The sensor contains an antenna that captures the energy from the router. The sensor stores that energy and, once there is enough, the sensor switches on, measures the temperature and sends a signal to the router. This signal has a slightly distinctive frequency, depending on the temperature measured. The router can deduce the temperature from this distinctive frequency.

The same technology enables other wireless sensors to be made, for example to measure movement, light and humidity. The application areas are enormous, Baltus noted, ranging from payment systems and wireless identification to smart buildings and industrial production systems. They won't be expensive either: mass production will keep the cost of a sensor down to about $0.20. The sensor is based on 65nm CMOS technology.

The project, called PREMISS, has received funding from the STW technology foundation. The title of Hao Gao's thesis is 'Fully Integrated Ultra-Low Power mm-Wave Wireless Sensor Design Methods.' The research was done in the Mixed-Signal Microelectronics group and also involved the TU/e groups Electromagnetics and Signal Processing Systems as well as the Centre of Wireless Technology. 

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Automotive Temperature & Humidity Sensor Market 2015-2019

Smart sensors are defined as a combination of a sensing element, an analog to digital converter (ADC), and an analog interface along with bus interface in one housing. Digital sensors also have a similar circuitry, therefore all digital sensors have been considered as smart sensors for this study.

In the automotive industry, smart sensors are utilized in applications like powertrain, body electronics, and alternative fuel vehicles (AFV). Rising demand for alternative powertrains along with alternative fuel vehicles is expected to drive the market for smart sensors in the automotive industry.

The market associated with the smart sensors for automotive application is poised to witness tremendous growth. Applications such as powertrain and AFV are expected to be high growth areas for smart relative humidity sensors.

This report covers the overall automotive temperature & humidity sensor market on the basis of different types of technology, packaging type, application, and geography. The major automotive applications considered for this study are powertrain, body electronics, and alternative fuel vehicles. The body electronics application has been further segmented into automatic HVAC control and auto defogger system.

Considering the geographical scenario of the automotive temperature & humidity sensor market APAC occupied the top position, followed by the Americas in 2013. The APAC region is also expected to exhibit the fastest growth, during the forecast period between 2014 and 2020.

Some of the major industry players in the automotive temperature & humidity sensor market are Sensirion AG (Switzerland), STMicroelectronics (Switzerland), Analog Devices Inc. (U.S.), Melexis NV (Belgium), NXP Semiconductor (Netherlands), Continental AG (Germany), and Robert Bosch GmbH (Germany) among others.

Key Topics Covered:
1 Introduction
2 Research Methodology
3 Executive Summary
4 Premium Insights
5 Market Overview
6 Industry Trends
7 Market, By Sensor Type
8 Market, By Technology
9 Market, By Packaging Type
10 Market, By Application
11 Market, By Geography
12 Competitive Landscape
13 Company Profiles
- Analog Devices, Inc.
- Continental AG
- Delphi Automotive Plc
- Epcos AG
- Honeywell International Inc.
- Measurement Specialities Inc.
- Melexis NV
- NXP Semiconductors
- On Semiconductor Corporation
- Robert Bosch GMBH
- Sensata Technologies, Inc.
- Sensirion AG
- Stmicroelectronics
- Texas Instruments (TI)

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Types of Temperature Sensors | isweek.com - Industry sourcing

There are two temperature sensing methods:
• Contact
• Non-contact

Contact sensing brings the sensor in physical contact with a substance or object. It can be used with solids, liquids or gases. Non-contact (infrared) temperature sensing reads temperature by intercepting a portion of the infrared energy emitted by an object or substance, and detecting its intensity. Non-contact is used to sense the temperature of solids and liquids. Non-contact cannot be used on gases due to their transparent nature.

Contact Temperature Sensor Types and Comparisons
Contact sensors, aside from capillary/bulb thermometers and bi-metal sensors, use varying voltage signals or resistance values.

Voltage Signals
Thermocouple sensors generate varying voltage signals. The different metal and alloy combinations in the thermocouple's legs produce a predictable voltage for a given temperature.

Resistance Values
Resistance temperature detectors (RTDs) generate varying resistance values. RTDs as a class are divided into two types:
• Resistance wire RTD
• Thermistor (thermally sensitive transistor)

RTDs work by producing a predictable resistance at a given temperature. Resistance wire RTDs (generally platinum) have a positive coefficient by increasing resistance with temperature increase. Thermistors are generally negative coefficient by decreasing resistance with temperature increase. Each of these three contact sensor types (RTDs, thermocouples, and thermistors) have advantages and disadvantages depending on application, desired response time and accuracy. A presentation of general benefits can help determine the most suitable contact sensor type.

Thermocouple Advantages
• Extremely high temperatures: Noble metal thermocouples may be rated as high as 1700°C (3100°F).
• Ruggedness: The thermocouples' inherent simplicity enables them to withstand shock and vibration.
• Small size/fast response: Thermocouples with exposed or grounded junctions offer nearly immediate response to temperature changes.

RTD Advantages
• Wide temperature range: Watlow platinum sensors cover temperatures from -200 to 650°C (-328 to 1200°F).
• Repeatability and stability: The platinum resistance RTD is the primary interpolation instrument used by the National Bureau of Standards from -260 to 630°C (-436 to 1135°F). Precision RTDs can be manufactured with stability of 0.0025°C per year. Industrial models typically drift less than 0.1°C per year.
• High output: The current drop across an RTD provides a much larger signal than thermocouple voltage output.
• Linearity: Platinum and copper element RTDs follow a more linear curve than thermocouples or most thermistors.
• System wiring cost: Unlike a thermocouple, an RTD uses ordinary copper leads for extension wires and requires no cold junction compensation.
• Area sensing: Point measurements, while often desirable, may cause errors. An RTD element can be spread over a large area, improving control with area averaging, a technique impractical with thermocouples.

Thermistor Advantages
Due to wide performance and cost variations among thermistors, generalized advantages and disadvantages may not always apply. Common benefits include:
• Low sensor cost: Most thermistors in their basic form cost much less than RTDs. When assembled in protective sheaths the price difference narrows.
• High resistance: Base resistance may be several thousand ohms. This provides a larger signal change compared to resistance wire RTDs with the same measuring current, negating leadwire resistance problems.
• Interchangeability: Many newer thermistor models are trimmed to very tight tolerances over limited temperature ranges.
• Point sensing: Thermistor beads may be pinhead size for point sensing.
Contact Sensor Conclusions
• Thermocouples are best suited to high temperatures, environmental extremes, or applications requiring microscopic size sensors.
• RTDs are best for most industrial measurements over a wide temperature range, especially when sensor stability is essential for proper control.
• Thermistors are best for low cost applications over limited temperature ranges.
________________________________________
Non-Contact Sensors
A non-contact (infrared) sensor intercepts and converts emitted infrared heat into a voltage signal. Construction characteristics of non-contact sensors use a lens to concentrate radiated infrared energy onto a thermopile. The voltage signal produced by the thermopile is sent onto an electronics package for amplification and conditioning before being retransmitted as either a voltage or current signal. Non-contact temperature sensors generally react and register (respond) faster than contact temperature sensors.

Non-Contact Temperature Sensor Advantages
The reasons for using non-contact over contact temperature sensing are:
• When physical contact with the object or substance would deface or contaminate
• The process or object moves
• A process requires a faster response than is possible with a contact sensor
• Can be isolated from contaminated or explosive environments by viewing through a window
________________________________________
Contact vs. Non-contact Sensor Comparisons
Contact Temperature Sensors

Advantages
• Relatively rugged
• Economical
• Wide application range
• Relatively accurate
• Simple to apply

Disadvantages
• Requires physical contact, may damage, mar or contaminate
• Can cause wear on rotary components (slip rings)
• Slow to respond relative to non-contact sensing
• Acts as a heatsink, alters readings on small objects
Non-contact Temperature Sensors

Advantages
• Relatively rugged
• Remote mounting away from heat source
• Ideal for measuring objects in motion
• Does not interfere with process
• Faster response (milliseconds compared to seconds for contact sensing)
• Can sense temperature of irregular shaped objects
• Will not deface, mar or contaminate
• Will not act as a heatsink

Disadvantages
• Will not measure gas temperatures
• Emissivity variations
• Field-of-view (spot size) restrictions
• Ambient temperature restrictions
• Indicated temperature affected by environmental conditions (dust, smoke, etc.)

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Temperature sensor: how do they work | isweek.com - Industry sourcing

The most basic definition of temperature sensor devices is that they are tools specially designed to measure the hotness or coolness of an object. However, sensors are actually measuring the atomic activity and movement of an object. When temperature sensor devices read an object with zero atomic activity, the temperature point is considered absolute zero. When a substance is heated, it usually moves through several phases: solid to liquid and from liquid to gas until the atomic activity begins increasing.

How temperature sensor devices measure temperature
There are four major measurement scales that are broken down and categorized into different degree units. They represent the method temperature sensing devices use to measure the molecular activity of an object.

Using the metric Celsius scale at a point of reference, the measuring scale begins at zero. Freezing water would measure zero while boiling water measures one hundred. If the Fahrenheit scale also starts with the zero measurement as the coldest object (freezing water) going from 32 degrees to boiling water measuring 212 degrees. Temperature reading devices recognize absolute zero measurements as near -460 degrees Fahrenheit. The absolute scale using Fahrenhiet temperature sensing is also called the Rankin scale. Absolute zero on the Rankin scale is 492 degrees Rankin.

Temperature measuring terminology
Understanding how temperature sensor equipment works requires that you also understand the industry terminology. For example, the accuracy of a temperature sensing device refers to how close the reading is to the actual temperature. When resolution is discussed, it is referring to the absolute smallest temperature change that will be noticed and registered on the device.

Linearity is the process of creating a record where you record how the accuracy changes showing a wide temperature range. The temperature range refers to the obvious difference between maximum and minimal temperature readings. The time constant is the amount of time it takes to measure a temperature change to accuracy. Time constants of temperature sensor devices record minutes in air, the seconds in still liquids and fraction seconds are measured in moving liquids.

A time tested temperature measuring method
There are still some older temperature sensor techniques being used by professionals today. Simple expansion is based on the principle that when most substances are heated they expand. This effect can be even greater by adding mercury or alcohol to a capillary tube which creates a well known temperature sensor device - A traditional thermometer.

Thermocouples
Thermocouples are another thermal measuring technique. A thermocouple is made from two different metals which are welded together. The combination of these two different metals has the potential to generate a powerful voltage similar in capacity to the temperature. In order to use this temperature measuring device, you would either need to add a second junction using freezing water or create an icepoint reference voltage to create resistance.

Thermocouples can be pricy and are not necessarily the easiest thermal measuring devices to work with, but many industry experts swear by these devices. These temperature sensor devices can provide some impressively diverse measurement ranges.

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