MECHANICAL MEASUREMENT AND METROLOGY

Sagar Bhatt . Hiren Sutariya R.

150053119031

GUIDED BYNILESH A PATEL. [LAB]UJAWALA S.SAIUNKHE [CLASS]

BITS EDU

CAMPUS

Operating principle Contraction & Working Advantage Disadvantage Application

OPTICAL PYROMETER

OPRERATING PRINCIPLE The Optical pyrometer works based on

the comparison of the intensity of visual radiation emitted by the object.

The color of an object is an indication of its temperature and the brightness of a hot object is also a measure of its temperature.

RANGE : - 760˚C to 3500˚C

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CONSTRUCTION & WORKING

Radiation from object are focussed by an objective lens upon the tungsten filament so that image of the object surface is formed exactly at the filament lamp.

The eye piece also adjusted until the filament is viewed through eyepiece so the filament is seen superimposed on the image of object surface.

The red filter is the allow only a short wavelength radiation to pass through it.

In optical pyrometer the brightness of object is matched with intensity of filament lamp.

Matching of brightness of the lamp filament with that of object surface is achieved by adjusting current supply to the filament lamp.

ADVANTAGE OF OPTICAL PYROMETER

Light weight and portable It may be battery operated , hence self

contained unit. Good accuracy compared to radiation pyrometer No direct contact is necessary with object whose

temperature to be measured The measurement is independent of the

distance between object & instrument Wide temperature rang

DISADVANTAGE OF OPTICAL PYROMETER

Emissivity of an object affects the accuracy of measurement.It may not useful to measure temperature below 700˚CNot useful for measuring the temperature of clean gasesAccuracy is depend on the operator adjustment of equal brightness of filament & object surface.Relatively expensive.

APPLICATION OF OPTICAL PYROMETER

It can be used to measure temperature of furnace interiors and molten metal

The optical pyrometer is used to measures the surface that cannot be touched or cannot be reached.

 Also its used for temperature measure in steam boiler, hot air balloons and gas turbine engine.

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