IR thermometry: fast and cost-effective measurement

Paul Boughton

With energy costs one of the top expenses for the process industries, accurate measurement is essential. The latest IR thermometry releases use the most up to date technology to ensure that measurement accuracy is the best ever

Raytek, a leading worldwide provider of infrared (IR) thermometry, has introduced the MI3 Series of IR temperature measurement sensors. According to the company, the M13 series represents a new generation of performance and innovation in non-contact temperature monitoring for original equipment manufacturer (OEM) applications and manufacturing processes.

The Raytek MI3 sensors are designed to deliver industry-leading performance and flexibility at the lowest installed cost per measurement point. Combining a rugged IP65 (NEMA 4) stainless steel sensing head with a separate communication module, the MI3 is designed to meet virtually any noncontact temperature measurement requirement (Fig. 1).

According to Bill Kolbeck, Raytek product manager - point sensor products, IR thermometers, such as the MI3, are the fastest, safest and most cost effective way to measure critical temperatures necessary for process control and automation: "Energy costs are typically one of the top three operating expenses in any manufacturing facility, and process heating is the largest portion of this expense. The Raytek MI3 reduces energy costs by allowing tighter process control and more efficient process heating. Improved control performance usually results in less product variation, higher product quality and increased throughput."

Kolbeck indicated the new MI3 sensor provides all the functionality of the proven Raytek MI Series with significant new features. These include a broad choice of sensing head temperature ranges and spectral responses, a standard USB 2.0 digital interface for easy sensor set-up and configuration, a fully programmable electronics platform, and response times as fast as 20 mSec. The thermometer's innovative multiple sensing head interface supports up to eight individually addressable heads per communication box.

Seamless integration

The Raytek MI3 Series sensors offer a choice of scalable 0/4 to 20 mA and 0 to 5/10 VDC analogue outputs, or Type J, K, R or S thermocouple outputs, as well as an optional RS485 network interface - thus, enabling seamless integration into existing control equipment or OEM systems.

Standard USB 2.0 communication facilitates sensor configuration and is valuable for troubleshooting when the device is installed in hostile or remote locations. Additionally, this capability saves maintenance time and minimises technician exposure to hazardous environments.

Robust field calibration software also allows on-site calibration of sensors, which further reduces service time and expense.

Silicon optics

Thanks to precision, high-resolution silicon optics, the MI3 sensors provide a range of optical resolutions (2:1, 10:1 or 22:1) at a very attractive price. For high-volume OEM applications, the sensing heads allow a direct digital interface to the host machine controller. The MI3MCOMM multichannel communications box supports up to four high-performance, miniature sensing heads in a convenient DIN-mountable package. All sensor-operating parameters are easily accessed and configured through the standard user interface with large backlit LCD display, or with the powerful Raytek DataTemp multidrop software via the USB 2.0 digital interface.

The MI3's user-programmable, isolated alarm output is an easy way to achieve alarm and control redundancy or provide simple on/off control capabilities. Its optically isolated relay allows for local alarm capability, eliminating the need for separate limit switches or alarms.

Other standard MI3 features include: adjustable emissivity, transmissivity, peak hold, valley hold and signal averaging; and configurable inputs for emissivity control, ambient background compensation and trigger/hold input.

Meanwhile, Land is emphasising the importance of critical vessel monitoring on-site.

When processes take place inside refractory lined vessels it is critical for safe plant operation to ensure the integrity of the refractory lining. In the event of refractory breakdown, hot gases come into contact with the vessel shell potentially causing catastrophic failure and risking costly unplanned shutdowns.

It has long been acknowledged that the most effective method for monitoring refractory integrity is through vessel skin temperature measurements.

"However this is typically performed using contact thermocouples bonded to the vessel surface and connected via a fibre optic mesh. The measurement coverage on the vessel is often one measurement per 250 cm2/0.25 ft2. Such systems are both expensive to install, require regular maintenance and often need to be replaced after less than three years of vessel operation," says the company.

Improved measurement density

The company adds that its proven Critical Vessel Monitoring system is able to provide a significantly improved measurement density with one measurement per 16c m2/0.02 ft2 allowing earlier detection of refractory breakdown, often before the problem becomes dangerous. The system uses low maintenance, industrial thermal imaging cameras installed around the vessel to maximise the coverage of the entire vessel and provide complete coverage of the critical dome and cone sections.

The company has 60 years of experience in designing and implementing custom solutions for individual customer requirements and says it has the core competencies necessary to provide a turnkey solution for.

Separately, the company has also announced the latest addition to its LANDSCAN product range. LSP-HD IR linescanners operate at frequencies of up to 150Hz with 1000 temperature measurement points per scan for the most detailed, highest resolution thermal images of processes. The company says that no other industrial IR line scanner comes close in terms of sheer image resolution.

Data is now processed on-board the sensor, eliminating the requirement for a separate processor. Direct PoE enabled Ethernet connectivity means LSP-HD scanners can be hooked straight up to a regular Ethernet network using a single M12 connector. Process I/O can be positioned anywhere on the network in the most convenient place for your control signals and can operate independently of any PC following initial setup.

LSP-HD is fully backwards compatible with existing LSP hardware and can be easily added to existing LANDSCAN systems without the requirement to replace working scanners.

High demand for handhelds

Handheld IR thermometers are one of the most popular types of infrared pyrometer. They are commonly used for portable applications although some models also feature an integral tripod mount. OMEGA offers a large variety of infrared thermometers in various shapes and form factors.

Many of the company's handheld IR pyrometers feature its patented Circle Dot/Circle Laser sighting which clearly outlines the field of view of the thermometer.

Its technologies includes the OS530L handheld IR thermometer, the OS643 pocket/stick type IR thermometer, the OS36 IR thermometer, the OS1551 Fixed-mount IR thermometer transmitter, and the IR2 two-colour ratio thermometer.

Commenting two-colour ratio thermometry, Omega says: "Given that emissivity plays such a vital role in obtaining accurate temperature data from infrared thermometers, it is not surprising that attempts have been made to design sensors which would measure independently of this variable. The best known and most commonly applied of these designs is the two colour-ratio thermometer. This technique is not dissimilar to the IR thermometers described so far, but measures the ratio of IR energy emitted from the material at two wavelengths, rather than the absolute energy at one wavelength or wave band."

Handheld IR themometers

Calex also offers a range of handheld IR thermometers, including its PyroPen Series. These compact, pen-style thermometers operate from -20°C to 500°C and have a USB model too. The ST640 Series is designed to be low cost, operate from -35°C to 550°C and comes with audible alarms. The ST680 Series comes in a rugged housing, operates from -50°C to 1000°C and also offers a USB model.

In terms of fixed IR temperature sensors, Calex has a broad selection, including PyroCouple, PyroCouple M, PyroEpsilon, PyroUSB, and PyroBUS - this with an RS485 Modbus interface, configurability and a touchscreen terminal option

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