Infrared temperature measurement
- Identification
- How does it work?
- What can it be used for?
- What can it not be used for?
- Implementation
- Related Facilities
- Further Information
Identification
| Key words | Infrared temperature measurement, infrared thermometers, emissivity, food safety, quality assurance, real-time |
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| Latest version | 2013/02/14 |
| Completed by | UTCN, IRTA |
How does it work?
| Primary objective | Online/real-time temperature measurement | |||
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| Working principle | Infrared (IR) thermometers for non-contact temperature measurement are sensors with wide-spread application in industrial processing and research.
IR thermometers capture the invisible infrared energy naturally emitted from all materials which are at temperatures above absolute zero (0º K). Infrared radiation is part of the electromagnetic spectrum which includes radio waves, microwaves, visible light, ultraviolet, gamma, and X-rays [2]. The IR part of the spectrum spans wavelengths from 0.7 to 1000 micrometers, but only frequencies between 0.7 and 20 micrometers are used for temperature measurement, because the current detectors are not sensitive enough to detect the very small amounts of energy. An IR thermo device is made of a lens to focus the infrared energy on to a detector, which converts the energy to an electrical signal, that is compensated through ambient temperature variation. The result is displayed in units of temperature.
The higher the emissivity of an object, the easier it is to obtain an accurate temperature measurement using infrared. Emissivity is the ratio of the energy radiated by an object at a given temperature compared to the energy emitted by a perfect radiator (or black body) at the same temperature. Values of emissivity fall between 0 and 1, the last number being the emissivity of a black body. Parameters that influence emmisivity are the material, surface structure (since part of the IR energy will be absorbed and part will be reflected) and regular geometry of the material. | |||
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| Additional effects |
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| Important process parameters | IR intensity, field of view, angle of measurement, response time | |||
| Important product parameters | Emissivity, temperature, dimensions |
What can it be used for?
| Products | Liquid or solid, in-flow or stationary. It can be used in cases where the object to be measured is moving, is surrounded by an electromagnetic field or controlled environment (e.g. vacuum). |
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| Operations | Temperature monitoring (through receiving, storage, cooking, holding and serving). |
| Solutions for short comings | Non-contact infrared thermometers are used in applications where fast temperature reading without physically touching the object is needed; f.i. temperature monitoring of hot, hazardous, or hard-to-reach surfaces without contaminating or damaging the object. IR thermometers also provide advantages as lightweight, ease-of-use and rapid detection. |
What can it NOT be used for?
| Products | It can not be used with reflective surfaces like stainless steel or aluminum. Depending on the field of view, samples with rought surface are not suitable for measurement. |
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| Operations | IR thermometers only measure surface temperature, being therefore a screening tool. When used for food applications, critical temperatures have to be measured with an internal device. |
| Other limitations |
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| Risks or hazards | Eye and skin damage can occur due to laser exposure. Therefore, direct exposure of the human eye needs to be avoided. Indirect exposure via reflective surfaces is also dangerous [3]. |
Implementation
| Maturity | Designs of an infrared thermometer have existed since at least the late nineteenth century, and some concepts were first revealed in 1911 [7].
Practical measuring instruments started being available in the 1930's, being widely used in industry and research nowadays [1]. |
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| Modularity /Implementation | It can be implemented in an existing production line. |
| Consumer aspects | Not known. |
| Legal aspects | Directive 2004/40/EC of the European Parliament and of the Council of 29 April 2004 on the minimum health and safety requirements regarding the exposure of workers to the risks arising from physical agents (electromagnetic fields). |
| Environmental aspects | Ease and speed of IR measurement triggered more frequent monitoring of the processes and storage temperatures, leading to decreased overall waste generation and energy costs. |
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Further Information
| Institutes | IRTA, DIL |
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| Companies | All QA Products, Calex Electronics, Comark Instruments, KELLER HCW, Land Instruments International, LumaSense Technologies, OMEGA Engineering, Optris, Raytek, Testo |
| References |
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