| The
Only Certified Accurate Surface Temperature Instruments in
the World
Download
D-Series brochure (PDF format)
D501
and D501-RS
Compare the Exergen Microscanner D-series thermometer with
conventional alternatives:
Common
Surface
Temperature
Measurement Factors |
Microscanner
D-series IR
Thermometers |
Conventional
IR "Point and Shoot" guns and probes,
including laser
aimed units |
Conventional
contact probes, thermocouples,
RTD's,
thermistors |
| 1.
Pre-set Emissivity errors? |
no
effect |
very
sensitive |
no
effect |
| 2.
Emissivity shift errors? |
no
effect |
very
sensitive |
no
effect |
| 3.
User adjustment errors? |
no
effect |
very
sensitive |
no
effect |
| 4.
Background reflection errors? |
no
effect |
very
sensitive |
no
effect |
| 5.
Contact errors? |
no
effect |
no
effect |
very
sensitive |
| 6.
Friction heating errors? |
no
effect |
no
effect |
very
sensitive |
| 7.
Heat sinking errors? |
no
effect |
no
effect |
very
sensitive |
| 8.
Time based errors? |
no
effect |
no
effect |
very
sensitive |
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.
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".
Also,
Quality Assurance programs should not rely upon any instrument
that allows users to alter the instrument settings and to
let it display whatever the user wishes.
4.
Background Reflection Errors
Even if emissivity is constant (see #2), there are still
errors induced by changing ambient temperatures. For example,
with emissivity = 0.9, ambient reflections account for 10%
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 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.
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