Non-Contact Temperature Measurements in Test Meters = Safety

Before climbing up a ladder to make a measurement or touching test leads to a high voltage breaker panel or making contact with an active motor, wouldn’t it be safer and faster to be able to simply point your measuring device at the target area to locate a hot spot?

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Before climbing up a ladder to make a measurement or touching test leads to a high voltage breaker panel or making contact with an active motor, wouldn’t it be safer and faster to be able to simply point your measuring device at the target area to locate a hot spot? Non-contact IR (InfraRed) thermometers are popular and effective instruments but many professionals do not want to have to carry around both an IR thermometer and a separate instrument for measuring voltage or current or airflow or humidity or RPMs.

Extech Instruments of Waltham, Massachusetts has developed a patented series of instruments which combine a built-in IR thermometer with Multimeters, AC/DC Clamp meters, Humidity Psychrometers, Hygro-Thermometers, Anemometers, and Tachometers.

In the developmental history of the multimeter for instance – a device which typically incorporates a voltmeter, an ammeter and an ohmmeter that is used for electrical troubleshooting – customer demand motivated Extech to add a temperature-measuring functionality to the meter. After all, excluding Time, temperature is the most commonly measured parameter. In the multimeter, it is a particularly useful capability since large temperature rises may signify impending problems with motors and electrical circuits. So the Type K thermocouple thermometer became a common function in the digital multimeter.

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Following Extech’s success with the multimeter, Type K temperature measurement was subsequently added as a function on other measuring devices, including digital clamp meters (professional HVAC contractors, in addition to electrical measurements, are constantly taking duct and electrical coil temperature measurements to ensure proper heating and cooling). Temperature is also an essential function incorporated in RH meters and Anemometers (temperature variations in an HVAC system may indicate air-flow and air balance issues).

After the overwhelming success of the Type K inclusion many engineers began focusing their attention on additional capabilities. “What next?” they asked. Certainly, more functions could be incorporated into one instrument, but if they weren’t logical additions with a customer benefit, the end result would be a kind of “Swiss Army knife” – an instrument with a variety of functions, many of which the user may never employ.

In 2002, Extech Instruments introduced a patented line of Digital Multimeters that included a built-in infrared thermometer. This development was extremely well received by the market and the success of the EX470 confirmed the results of Extech’s initial focus group studies. Following the success of the Multimeter, Extech quickly followed with the introduction of a Clamp Meter, a Tachometer, an Anemometer, a Humidity Psychrometer, and a Hygro-Thermometer, all incorporating IR technology. Patents are also pending on these devices.

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Using built-in IR thermometers, these instruments now provide the ability to acquire temperature readings in a wide variety of applications using non-contact technology. The IR thermometers incorporated into the Extech products feature a temperature range as low as -58°F (-50°C) to a high of 932°F (500°C). A built-in laser pointer allows the user to quickly pin point the target area which is essential for small targets and for the measurement of surface temperatures, including those in especially hard-to-reach areas.

The value of this non-contact performance cannot be overstated. Non-contact temperature measurements are not only more convenient they are substantially safer. First, it eliminates the need for a user to get too close to a hot or high-voltage object. Secondly, it allows measurement in hard-to-reach places, where making actual contact with the measured surface is impractical. The HVAC technician measuring vent surface temperatures, for example, might be hindered by the height of the vents. Non-contact IR enables that technician to take an accurate measurement from a distance.

These are merely a few of the advantages offered by IR technology. Large surfaces also lend themselves to IR temperature measurement. Using a probe to evaluate a large area requires the user to physically take readings at a variety of points to average them out for an overall figure. IR provides instantaneous readings with a simple scan over the entire surface area. The technology is equally advantageous where probe contact can potentially damage a fragile surface, contaminate a process or when solid contact cannot be assured, such as on a wet surface.

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In some cases, IR temperature measurement is a supplement to contact-type measurement, and in others it gives the instrument a brand-new capability. Take the tachometer for instance. Before the IR capability was added to this device, it had no temperature measurement capability. It was Extech’s foresight that has brought temperature measurement, and therefore added value, to this instrument.

Why does a tachometer need this capability? Tachometers allow the user to compute the speed of a rotating part; as a result, electricians and other maintenance personnel rely on them to ensure proper operation of motors, engines, rollers, gearboxes and other moving machinery parts. The addition of IR temperature capability to Extech’s RPM-10 Tachometer offers a more productive way of detecting shaft misalignment, bad couplings and other maintenance problems early and allowing for more effective preventive maintenance.

Additional instruments in the Extech line that incorporate the IR technology include the Anemometer, the Psychrometer and the Hygro-Thermometer. The IR addition to the AN200 Anemometer enables HVAC contractors to measure vent temperatures without climbing a ladder. The IR addition to the RH401 Psychrometer and the RH101 Hygro-Thermometer creates a very powerful tool in the fight against mold and mildew. In order to understand when humidity and temperature conditions can lead to detrimental condensation an HVAC contractor needs a way to measure surface areas that can be unreachable such as in a crawl space under a building. In addition to measuring relative humidity and air temperature the RH401 Psychrometer also calculates dew point and wet bulb and the T1 – DP (Dew Point) to determine the first condensing surface.

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Besides the obvious convenience of combining two functions in one instrument – saving both time and money – there is the issue of calibration. When functions are combined into single device housing, only one calibration is required. This can represent a significant dollar savings, particularly for companies that are ISO 9000 certified and must calibrate their instruments annually.

According to Scott Black, senior product manager at Extech Instruments, the initial addition of IR temperature measurement to his company’s multimeters was catalyzed not only by an obvious market need but by the need to differentiate Extech’s products in a crowded marketplace.

“Multimeters represent a highly competitive business,” he said. “Everyone is striving to provide an accurate, high-resolution instrument. But the company that can provide additional product features and benefits to a line of meters can separate itself from the pack. That’s what we’ve tried to do with the IR technology, not just with our multimeters but with our other instrument lines as well.

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While the impact of IR’s usage in the Extech instrument line has been noteworthy, the actual inclusion of IR technology into the instruments presented a technical challenge. “IR technology was already well-established,” Black explained. “Our challenge was to figure out how to squeeze the IR technology into the instruments. It was both a technical challenge and a physical one and we overcame this with innovative engineering and creative product design which enhanced our branding efforts.”

“There was a clear opportunity here for Extech,” adds Jerry Blakeley, president of Extech. “No one would argue that there were already a large number of dual- and even triple-purpose devices. The key, as we’ve always said, was not to simply pile on more features, but to add those which made sense for the customer. In that respect, adding IR made a lot of sense for our customers and fortunately we were able to get international patents on our designs.”

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