Inexpensive method of temperature measurement is the use of non-contact IR pyrometer (thermometer). The device can be directed at the object from different distances. Limits – transparency of the environment and the measuring spot diameter.
Consider some of the types of pyrometers.
IR pyrometer monochrome
The principle of operation of the device is the measurement in the IR spectrum of the absolute value of the emitted energy of a single wave. Is considered a relatively inexpensive method of measuring temperature at a distance. These thermometers are able to operate on the principle of “point and shot”.
The disadvantage is the sensitivity to pollution of the environment. Therefore, in humid, smoggy and dusty environments limited. The readings of these thermometers can influence of strong electromagnetic fields. Therefore, the use of monochromatic IR pyrometer near induction heating systems is not recommended.
Infrared thermocouple
The characteristics of these thermometers is almost similar to the devices of the previous type. The fundamental difference in the transformation of the incoming signal. IR single color pyrometer for this operation use the detectors (silicon, thin film) and various electronics (amplification and conversion of signal). Infrared thermocouple (infrared thermometer) only transformerait light emission in nonlinear thermocouple signal.
The main advantage of thermocouples is low cost and compatibility with different measuring instruments having analogue (usually HA) thermocouple input:
- Controls;
- Measures;
the flight Recorders.
The lack of electronics not only reduces the cost of the device but also increases the maximum operating temperature of the thermocouple. It is slightly higher than that of the other devices.
The main disadvantages – high enough (2%) accuracy and wide spectral range.
IR pyrometer two-tone
The principle of operation two-color infrared pyrometers – the measurement of the ratio of values of the radiated energy waves (two and above) obtained in the different color spectra. Single-color infrared thermometers measure the value of the emitted energy of one wave in the IR spectrum. Such devices are capable of measuring the temperature of an object (subject), even through a dusty screen glass in a furnace.
Fibre optic pyrometers
the Principle of operation resembles the operation of a single-color infrared thermometers. Only transportation of light flux to the detector is performed via fiber optic cable (bent in any form). Therefore, measurement can be carried out in remote places, and not in the direct field of view. Fiber optic cable:
- resists the effects of electromagnetic fields;
- Resistant to serious pressure;
- Has a maximum (up to 200°C) operating temperature.
Fixed focus is both the advantage and disadvantage of such pyrometers.
If you want to explore in more detail issues associated with the methods of temperature measurement or more details to learn about thermometers and thermal imagers, we encourage you to enroll in our training courses TOR-104 “Thermal method of nondestructive control. IR pyrometers and thermometers”.