Just when you thought there’s nothing more to the good-old pyrometer, we’re here with 3 amazing facts.
Did you know there’s a variation called “Optical Pyrometer” that measures temperature based on the emitted light of an object? Cool, right?
Pyrometers, in general, measure temperature from far away so you can keep your distance. If you’re hearing about pyrometers for the first time, you’ll want to ask, “What’s a pyrometer, how does it work, and how many types of pyrometers are there?”
We’ll answer them all here. Hop in!
What’s the Temperature Range of a Pyrometer?
If you ever wondered- what’s the highest temperature a pyrometer can read, our first fact will surprise you! It turns out a pyrometer can measure temperatures up to four thousand Celsius. Infrared pyrometers (radiation pyrometers, if we may) stay within the -18°C to 870°C range.
How Do Pyrometers Work?
A radiation pyrometer detects radiation in the 2-14um infrared range. When you point it at the heated source, the radiated energy first passes through a lens and gets absorbed into the screen. There’s also a rheostat, a PMMC meter, and a battery.
Optical pyrometers measure the photometric brightness of an object and compare it to that of a fixed source. Usually, this standard source is an incandescent filament.
Types of Pyrometers
Fact number three is- there are four different pirometer for industrial use. Let’s get to know them.
A radiation pyrometer is similar to a contactless thermometer. It catches the radiation of an object and translates the reading to a temperature unit. These pyrometers are very accurate and can read temperatures up to a few thousand degrees Celsius.
Now, speaking of accuracy, a monochromatic brightness radiation pyrometer is the most accurate of all. Well, maybe not as much as two-wavelength pyrometers.
A dissolving filament is placed inside this type of pyrometer. First, it matches the brightness of your object to that of the filament. It amounts to a certain level of temperature on your screen. Optical pyrometers are used in the metal extraction and processing industry for measuring the temperature of molten materials.
The spot pyrometer is a simple device with a fixed thermal unit. Its infrared measurement sensor is pretty reliable for a specified area of your object. However, it doesn’t account for the changes in emissivity, which can often lead to statistical deviation.
Ratio pyrometers or two-wavelength pyrometers operate at two different wavelengths. It helps the pyrometer accurately measure large bodies, especially when the radiation level is variable.
Most people don’t know this, but a two-wavelength pyrometer is actually the most accurate one of all. It’s the only pyrometer that compensates for the fluctuating surface emissivity.