Exergen manual D-Series Handheld IR Scanners, Temperature

D-Series Handheld IR Scanners

The D-Series is an entirely different type of instrument than conventional temperature measuring devices. Designed specifically for the highest possible accuracy, it is the only infrared instrument which can be certified as to NIST-tracable accuracy on real surfaces of unknown emissivity, while completely free of contact errors and heat sinking errors of contact devices.

Actual measurement area is in the center, well away from the area contacted by the edge of the cone.

Recessed cone traps all emitted surface radiation, and blocks out any radiation from environment.

Only a thin lip of material actually contacts the target, thus minimizing heat transfer.

Reflective cone automatically corrects for emissivity variations by creating an actual blackbody at the precise location of measurement.

Figure 1. Unique Automatic Emissivity Compensation System (AECS) produces accurate temperatures everywhere the infrared probe is placed, by creating its own blackbody.

1. Emissivity errors

The true emissivity of a surface is known only approximately. Conventional IR devices without Exergen’s Automatic Emissivity Compensation System can only display an approximate temperature over their entire temperature range.

The “accuracy” specifications given by most manufacturers are only for a “black body” calibration and do not hold outside laboratory conditions. Black body calibrations do not include emissivity shifts, ambient change effects on the target, and other phenomena that introduce significant errors.

Effect of Emissivity on Temperature Reading for a

500°F (260°C) Target in 70°F (21°C) ambient

550			D-Series using marker		290
500
450			D-Series w/o marker		deg C
deg F
400					200
350		Conventional Infrared
300					150
1	0.8	0.6	0.4	0.2	0
Non-metals and Oxides			Emissivity	Clean Metals

Figure 2. D-Series is accurate over a wide emissivity range, sufficient to include all non-metals. If a marker (or any other non-metal coating) is used, the D-series is accurate on clean metals as well. Conventional IR devices have considerable inaccuracy.

2. Emissivity shift errors

Even if an IR “gun” is set to the correct emissivity to read a surface

accurately at a particular temperature, it does not mean that the IR ε “gun” will read the same target correctly at other temperatures.

Emissivity of virtually all surfaces changes with temperature. A common assumption for conventional IR thermometry is that emissivity is constant with changes in target surface temperature. Real materials do not have this characteristic.

Actual emissivity

Conventional IR assumption

Temperature

51 Water Street, Watertown, MA 02172 USA

800-422-3006 • 617-923-9900 • Fax 617-923-9911