In many industrial applications, contact based temperature measurement is not suitable or ideal, for example, because the contact measurement speed is slow, the object is difficult to approach, or the contact probe may affect the measured object. In these cases, non-contact temperature measurement is the preferred method. They are used in many industrial applications, such as controlling the manufacturing process of very hot or fast moving objects, such as glass and metal manufacturing, and food and pharmaceutical industries with special hygiene requirements.
The non-contact temperature measurement has many advantages, such as:
Measurement of moving or vibrating objects
Fast measurement speed of multiple values per second
Measurement in explosive, corrosive, high pressure or high temperature environment
No physical or chemical influence on the measured object
Long life and low maintenance of measuring system
In industrial temperature measurement applications, the emissivity of objects plays a crucial role. The emissivity of human body is close to 0.98. Therefore, it is close to 1. The non-contact human body temperature measurement can be ignored. If the emissivity is significantly less than the unit (e.g. 0.9), careful consideration must be given. This is especially true for metals or glasses, which are typical examples of materials that require non-contact temperature measurement during manufacturing. In addition, the emissivity depends not only on the material, but also on the temperature, oxidation state and processing method of the material. Remote temperature measurement in industrial applications usually starts with a detailed understanding of the target emissivity under the precise conditions of the expected measurement.
A key factor in accurate industrial measurement is to select the correct filter in front of the infrared thermopile sensor. In order to reduce the dependence of changing atmospheric transmittance between the sensor and the target, a high-quality optical filter in the range of 8-14 µ m should normally be included. This wavelength range, also known as the far infrared atmospheric window, has almost no absorption. Therefore, the radiation from the object of interest received by the sensor has almost no change, independent of environmental conditions such as ambient temperature or humidity.
F8-14 standard filter has sharp edges at 8 and 14 µ m, so it provides an ideal filter for accurate and high-quality industrial measurement with low distance dependence.
Other applications of industrial process control include welding and weld repair, friction welding, exhaust temperature monitoring, and temperature observation with permanently installed or hand-held pyrometers.
The most commonly used sensor series for industrial remote temperature measurement are:
Heimann Sensor
Heimann HTS L Series
Heimann L-Series
Heimann thermopile array
