Eight reasons to consider Exergen D-Series infrared thermometersDecember 2, 2014 REDWIRE is news you can use from leading suppliers. Powered by FRASERS.
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Exergen D-Series infrared (IR) thermometers are an entirely different type of instrument than conventional temperature measuring devices. Designed specifically for the highest possible accuracy, it is the only infrared instrument that can be certified to NIST-traceable accuracy on real surfaces of unknown emissivity, while completely free of contact errors and heat sinking errors of contact devices.
Below are eight additional reasons to consider the D-Series over conventional temperature measuring devices.
1. Pre-set 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.
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 ”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.
3. User adjustment errors
A setting of emissivity = 0.9 on an IR ”gun” from one manufacturer will not necessarily match that of another IR ”gun” manufacturer. There are no standards set in the industry on the precise measurement and meaning of ”emissivity.”
4. Background reflection errors
Even if emissivity is constant, there are still errors induced by changing ambient temperatures. For example, with emissivity = 0.9, ambient reflections account for 10 per cent of the signal that the IR ”gun” will see. If ambient changes, the IR ”gun” will display a different target temperature, even if the target remains at the same temperature.
5. Contact errors
Thermocouples, RTDs. thermistors and other contact devices only measure their own temperature. They do not measure surface temperature. Published ”accuracy” specifications are for the probes only, not the surfaces they must measure. Users must guarantee that the probes are brought to the same temperature as the surface. Can you guarantee that your probes are brought to the same temperature as the targets to be measured?
6. Friction heating errors
For moving surfaces, a contact probe is prone to frictional heating. The size of the error is dependent on the roughness of the surface, the speed, the coating on the probe, and so on. It is impossible to control all the variables.
7. Heat sinking errors
For most non-metals, heat sinking errors can be quite large. The heat transfer rate of the metal leads required on ”contact probes” conducts heat faster than the target material can replace, resulting in unknown and fairly large errors. In general, the less dense the target material, the larger the heat sinking error with a contact probe.
8. Time-based errors
Contact temperature probes are slow. The temperature of a target can change more quickly than most probes, resulting in errors in real-time measurement.
Exergen D-Series infrared thermometers are available through Mod-Tronic Instruments.