Optical Pyrometer: Working Principle, Diagram, Advantages, Temperature Measurement [Animation Video]

Summary

In this video, we explore the working principle of the Optical Pyrometer, a non-contact device used for measuring high temperatures up to 15,000°C. The device compares the image of radiation from a hot body with that of a filament lamp by varying the current intensity. The optical pyrometer works by adjusting the brightness of the filament image until it matches the brightness of the hot body. It is portable, lightweight, and useful for high-temperature measurements, including for moving objects. However, it has limitations such as measuring only radiating bodies and potential human error, with the device being expensive.

Takeaways

• 😀 Optical Pyrometer is used for measuring high temperatures, up to 15,000°C.
• 😀 It is a non-contact type device based on comparing the radiation of a hot body and a filament lamp.
• 😀 The pyrometer consists of a hot body, lamp, lenses, absorption screen, and a filter.
• 😀 The absorption screen absorbs the radiant energy coming from the lens and creates the color image of the filament lamp.
• 😀 The filament lamp's brightness is adjusted by varying the current intensity through a rheostat.
• 😀 Temperature measurement is carried out when the brightness of the filament matches that of the hot body.
• 😀 Three conditions are used to measure temperature: when the filament is too bright, too dark, or perfectly matched in brightness with the hot body.
• 😀 The temperature is directly proportional to the color of the filament, which is controlled by the current passing through it.
• 😀 Optical pyrometers can be calibrated based on filament color to determine the temperature of a hot body.
• 😀 Advantages include portability, lightweight design, and the ability to measure temperatures of moving objects.
• 😀 Disadvantages include that it only measures radiating hot bodies, has a chance of human error, and is expensive.

Q & A

What is an optical pyrometer used for?

An optical pyrometer is used for high temperature measurement, up to 15,000 degrees Celsius, without making direct contact with the hot object.

How does an optical pyrometer work?

It works by comparing the image of radiation from the hot body with the filament lamp's radiation by varying the current intensity. It uses lenses to pick up radiated energy from the hot body.

What components make up an optical pyrometer?

An optical pyrometer consists of a hot body, a filament lamp, lenses, an absorption screen, and a filter.

What role does the absorption screen play in an optical pyrometer?

The absorption screen absorbs the radiant energy from the lens and creates an image of color, which is then compared to the filament lamp’s image.

How is the brightness of the filament lamp controlled in an optical pyrometer?

The brightness of the filament lamp is controlled by varying the current passing through it using a rheostat.

What are the three conditions for measuring temperature with an optical pyrometer?

1) When the filament lamp is brighter than the hot body, 2) When the filament lamp is darker than the hot body, and 3) When the filament lamp and hot body have equal brightness.

How is temperature determined in an optical pyrometer?

Temperature is determined when the brightness of the filament lamp matches the brightness of the hot body. At this point, the filament lamp disappears, indicating equal brightness.

What is the relationship between the filament’s color and temperature in an optical pyrometer?

The color of the filament is directly proportional to the temperature being measured, as the filament’s temperature is determined by the current passing through it.

What are the advantages of using an optical pyrometer?

Advantages include portability, light weight, ability to measure temperatures of moving objects, and suitability for high-temperature measurements.

What are the disadvantages of optical pyrometers?

Disadvantages include its ability to only measure radiating hot bodies, the possibility of human error, and its high cost.