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TempFlows

A knowledge website of Flow Research

TempFlows is a knowledge website of Flow Research that focuses on temperature products.  We do off-the-shelf and custom studies on temperature sensors, transmitters, infrared thermometers, and other temperature products.

Market Studies on Temperature:

The Market for Temperature Sensors in the Americas, 2nd Edition - Now Shipping!

The Market for Temperature Transmitters in the Americas, 2nd Edition - Now Shipping!

The World Market for Infrared Thermometers and Thermal Imagers

Articles about Temperature  Links to Temperature Sensor Suppliers

Temperature Sensors

Our temperature sensors study includes the following types of temperature sensors and accessories:

• Thermocouples
• Resistance Temperature Detectors (RTDs)
• Thermistors
• Infrared Thermometers
• Fiber Optic Temperature Sensors
• Thermowells

Flow Research completed the first edition of our temperature sensors study in 2000. A lot has changed in the temperature sensors market since that time.  A substantial amount of consolidation has taken place, involving all the different types of sensors.  The following is a summary of some of the merger and acquisition changes that have occurred in the temperature sensors business in the past seven years.

• Wika purchased US-based Alltemp Sensors, a manufacturer of thermocouples and RTDs, in 1999.  Wika is based in Alberta, Canada.  Wika is now a dominant player in the temperature sensors market, especially in Canada.

• Victory Engineering, a supplier of thermistors, was purchased by YSI, the leading supplier of thermistors in 1999.  This transaction took place in 1999.

• In May 2000, Mikron Instruments purchased E2 Technologies, a manufacturer of infrared thermometers.  Mikron  subsequently changed its name to Mikron Infrared.

• Cooper Instrument Corp. bought Atkins Technical in October 2001, and formed a company called Cooper-Atkins.  

• GE Sensing purchased Thermometrics in November 2001, when it bought the Sensing Solutions group of Spirent plc.  Thermometrics was previously the second-leading supplier of thermistors to the Americas.

• Fluke, which is based in Everett, Washington, purchased Raytek, the leading supplier of infrared thermometers.  This occurred in September 2002.  Raytek is located in Santa Cruz, California.

• Honeywell purchased Invensys’ Sensor System group in December 2002.  This included Fenwal, Elmwood, Clarostat, Sensym, Electro, Hobbs, and NEI.  Of these, Fenwal was a manufacturer of thermistors, and Honeywell  now has a significant place in that market.

• On January 1, 2005, Thermo Electric was sold to a private investment company.  This company also owns Correge Sensors , which makes thermocouple wafers for the semiconductor industry.  Thermo Electric is located in Saddle Brook, New Jersey and Brampton, Ontario, Canada.  Correge Sensors is in West Chester, Pennsylvania.

• In April 2006, Measurement Specialties acquired YSI Temperature, a portion of YSI, and BetaTHERM, both manufacturers of thermistors.

• In May 2006, Engelhard was acquired by BASF.  BASF is a major chemical supplier based in Germany.  Engelhard is a manufacturer of fiber optic temperature sensors located in Iselin, New Jersey.

Temperature Transmitters

Temperature transmitters take input from a temperature sensor and convert it into a form that is suitable for transmitting a signal over a long distance. Most temperature transmitters either convert the sensor signal to 4-20 mA or to some type of digital signal. In the process of doing this, the signal is conditioned and amplified so it can more easily be transmitted.  This is necessary because the voltage or resistance signal of most temperature sensors is very small.  It is difficult to transmit this signal accurately over a distance due to wire resistance and electromagnetic or radio frequency (RF) interference.

There are five main types or temperature transmitters. These types are as follows:

•  Low-Cost

• Analog

• Programmable

• Smart

• High-Tier

Low-Cost Temperature Transmitters

The term ‘low-cost’ is obviously a relative term, and what is “low cost” to one person might not be “low cost” to another.  The term ‘low cost’ also has a different meaning for temperature transmitters than it does for other field devices such as pressure transmitters.  This is because the prices of temperature transmitters are consistently lower than the prices of pressure transmitters.  This is primarily due to the more complex and sophisticated sensors required for pressure transmitters when compared to temperature transmitters.  Also, the cost of the sensor is included in the price of a pressure transmitter, while for temperature transmitters sensor cost is a separate item.  The prices of pressure transmitters range from under $200 to over $1,000, while temperature transmitters are available for under $100.  A price of $250 might be considered “low cost” for a pressure transmitter, but $250 is close to an average price for an analog temperature transmitter.

Analog Temperature Transmitters

Analog transmitters are very widely used, and they are used when a 4-20 mA signal is desired.  There is a very large installed base of analog temperature transmitters in process and other manufacturing plants.  Because end-users often replace like with like when ordering a replacement product, analog transmitters still form a large portion of the temperature transmitter market.

The primary characteristic of analog temperature transmitters is having a 4-20 mA output.  Just as there is a very large installed base of analog temperature transmitters in manufacturing plants, so there is a very large installed base of controllers and monitors that accept a 4-20 mA input.  This is changing over time as new plants are built and as more companies buy more instrumentation.  However, “smart” never had the same impact on the temperature market that it did in pressure or even flow, and many users are still buying analog temperature transmitters. 

Programmable Temperature Transmitters

Some analog temperature transmitters can be programmed used a handheld device or a personal computer.  Values that are typically programmed into a temperature transmitter are sensor type (e.g., a thermocouple of a certain type or an RTD), span value, etc.  While smart temperature transmitters are programmable by definition, there is a group of primarily analog transmitters that are called “programmable.”  These have the same features as analog transmitters, except that they are programmable. 

Smart Temperature Transmitters

Honeywell introduced the first smart pressure transmitter in 1983.  Since that time, “smart” devices have gained in popularity each year.  Even so, it took nearly ten years for smart pressure transmitters to gain substantial market share. Users are often very slow to adapt to new technologies, and installed base has a major impact on decision making.  As noted above, smart temperature transmitters have never had the same popularity as smart pressure transmitters.

The primary characteristic of a smart temperature transmitter is having a digital output.  However, “smart” refers to more than one characteristic.  To be smart, device must have the following three features:

• Microprocessor based

•  Digital output

• Capable of remote two-way communication

The above are defining characteristics for any field device to be smart.  The following are additional characteristics that smart transmitters typically have:

• Higher accuracy than analog transmitters

• Remotely programmable

•  Capable of accepting more than one type of sensor

High-Tier Temperature Transmitters

In addition to smart temperature transmitters, leading suppliers have also introduced enhanced, high-performance temperature transmitters called “high-tier” temperature transmitters.  While these transmitters are smart devices, they are more advanced than most smart transmitters and are characterized by features that enhance performance rather than their ability to communicate with other devices.  These features include the following:

• Higher accuracy than smart temperature transmitter

• Capability of accepting more than one type of sensor

Examples of high-tier temperature transmitters include Rosemount’s 3144 and 3244, and Honeywell’s STT350.

Fieldbus Temperature Transmitters

The efforts to create a universal fieldbus began in 1985, and they are continuing today.  A fieldbus is a communication protocol that enables devices from different vendors to operate together.  A fieldbus also makes it possible to send a number of signals from  field devices to the control room over the same pair of wires.  This drastically reduces wiring requirements because it is no longer necessary to dedicate one pair of wires to each field device.  Finally, fieldbus makes it possible for field devices to talk to each other directly, instead of communicating only via the control room.

The two primary fieldbuses available today are Foundation Fieldbus and Profibus P.A. (process automation).  While many or the world’s competing suppliers, including Rosemount, Honeywell, and Yokogawa, have rallied around the Fieldbus Foundation protocol, hopes for a universally accepted fieldbus have been dashed by continued support for Profibus P.A.  Support for Profibus P.A. comes from Siemens and companies that develop Siemens products, and it is strongest in Europe.  Profibus has not gained much of a foothold in North America.  However, Siemens’ strength in Europe means that these protocols will continue to compete for the foreseeable future.

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