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NON-CONTACT

TEMPERATURE DEVICES

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PyrometerFrom a Greek word

pyrowhich means fire

meterwhich means to measure

Used for measuring high temperatures and

where contact with the object is not possible

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Types of pyrometers

Infrared

Pyrometer

Optical

Pyrometer

Acoustic

Pyrometer

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INFRARED

PYROMETER

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INFRARED PYROMETER

Basis of Operation

Any object with a temperature above absolute zero will

radiate electromagnetic energy.

Infrared pyrometers measure the amount ofenergy

radiated from an object in order to determine its

temperature.

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INFRARED PYROMETER

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Different types of infrared pyrometers

Total radiation- This type of radiation thermometer measures all theenergy, over a broad spectrum, emitted by the object.

Single wavelength- Measures the magnitude of radiation at one

wavelength. This optimizes the accuracy of the device by selectingthe wavelength best suited to the object being measured. This type ofmeasurement provides good accuracy provided that the emissivity isknown.

Dual wavelength- When the emissivity is low and hard to measure, or

even variable, accuracy and reliability can be improved with a dualwavelength sensor. This type measures the magnitude of twowavelengths at the same time. The temperature is calculated from

the two readings.

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Advantages- Non contact measurement

- High temperature sensing

- Remote sensing

- Fast response and can sense

objects in motion

- Sense small or area target

INFRARED PYROMETER

Disadvantages- Expensive

- Non-linear response

- Subject to emissivity of material

- Require wide range of operation

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Application and Limitations

Relies onthermal radiation leaving the material being

measured.

The accuracy is affected by reflections, presence ofgases in

the radiation path and the surface emissivity of the object.

The surface emissivity can vary with wavelength, temperature

and also the chemical composition of the object beingmeasured.

INFRARED PYROMETER

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Automation

Dual and Multi Wavelength Industrial Infrared

Scanner

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Automation

Line Scanners

Lowest Measured:

0 F / 35 C

Highest MeasuredTemperature:

4500 F / 2500 C

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OPTICAL

PYROMETER

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OPTICAL PYROMETER

BASIS OF OPERATION

Brightness comparisonis made to measure the temperature. As ameasure of the reference temperature, a color change with thegrowth in temperature is taken.

The reference temperature is produced by a lamp whosebrightness can be adjusted till its intensity becomes equal tothe brightness of the source object.

For an object, its light intensity always depends on the

temperature of the object, whatever may be its wavelength.After adjusting the temperature, the current passing through itis measured using a multimeter, as its value will beproportional to the temperature of the source when calibrated.

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OPTICAL PYROMETER

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Here you can see the first

patent of disappearing-filament optical pyrometer

granted to Morse in 1899.

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Advantages Simple assembling of the device

enables easy use of it.

Provides a very high accuracy

with +/-5 degree Celsius.

There is no need of any direct

body contactbetween the

optical pyrometer and the

object.

The device can be used for

remote sensing.

Can also be used to see the

heat produced by the

object/source.

Disadvantages As the measurement is based on

the light intensity, the device can

be used only in applications with a

minimum temperature of700

degree Celsius.

The device is not useful for

obtaining continuous values of

temperatures at small intervals.

OPTICAL PYROMETER

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Applications

Used to measure temperatures ofliquid metals orhighly heated materials.

Can be used to measure furnace temperatures.

OPTICAL PYROMETER

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ACOUSTIC

PYROMETER

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Acoustic pyrometer

Basis of Operation

The speed of sound in a gas is dependent on the

nature of the gas and its temperature. The time offlight is used, and since the distance between points is

known it is possible to measure any change in

conditions. This principle is adapted for liquid and solid

temperature m.easurement also

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Acoustic pyrometer

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Acoustic Signal

Generator

Acoustic pyrometer

Signal Receiver

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Acoustic pyrometer

Single Path Measurement Multi-path Measurement

Zonal Mapping System

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AUTOMATION