The document discusses the operating principle, construction, working, advantages, disadvantages, and applications of an optical pyrometer. An optical pyrometer works by comparing the intensity of visual radiation emitted by an object to the brightness of a heated tungsten filament. It has a range of -760°C to 3500°C. Radiation from the object is focused through lenses onto the filament to match their brightness, allowing temperature measurement. Advantages include portability, accuracy, and non-contact use over a wide temperature range, while disadvantages are emissivity effects and limited accuracy below 700°C. Applications include measuring furnace and molten metal temperatures.

1. MECHANICAL MEASUREMENT
AND METROLOGY
Sagar Bhatt .
Hiren Sutariya R. 150053119031
GUIDED BY
NILESH A PATEL. [LAB]
UJAWALA S.SAIUNKHE [CLASS]
BITS EDU CAMPUS

2. ∗ Operating principle
∗ Contraction & Working
∗ Advantage
∗ Disadvantage
∗ Application
OPTICAL PYROMETER

3. 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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4. CONSTRUCTION & WORKING

6.  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.

7. 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

8. DISADVANTAGE OF OPTICAL
PYROMETER
 Emissivity of an object affects the accuracy of
measurement.
It may not useful to measure temperature below 700˚C
Not useful for measuring the temperature of clean
gases
Accuracy is depend on the operator adjustment of equal
brightness of filament & object surface.
Relatively expensive.

9. 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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