Infrared thermometers are instruments which have become an integral part of every household as well as industry sector. As a temperature gauging instrument its accuracy is indubitable. For this accuracy and reliability, it finds application in many areas like food industry, in household applications, in the medical industry, in HVAC maintenance, and in industrial processes among many others.

However, it is also essential to take proper care of infrared thermometer for longer shelf life and greater accuracy. Here are a few tips for you to maintain your valuable tool.

• Taking care of the batteries: Always make sure that the China infrared thermometers have enough backup batteries for better functionality. Also make sure that you are using a new good quality alkaline battery. If you are replacing them make sure to check the polarity on your batteries. Install only as per the diagrams in the battery compartment.
• Keep moisture at bay: Regular exposure to moisture is very essential for proper maintenance of your temperature gauging equipment. Always, place infrared thermometers in a moisture free zone, so that it doesn’t ruin and mold the screen. This may lead to malfunction or damage beyond repair.
• Get it repaired only from manufacturers: If in case the infrared thermometer need repairing, always go to its rightful manufacturer. Getting it done locally may result in further damage that may be irreparable forever.
• For cleaning, use only branded products: Always follow the instructions given in the product’s manual guide while cleaning infrared thermometers. It is recommended that you use branded products. Go for compressed air (in an aerosol can); a soft rag; Endust for Electronics, or any non-abrasive household cleaning fluid suitable for cleaning plastic. You may spray a small amount of fluid onto a rag and go for cleaning.

These maintenance instructions for infrared thermometers, digital pressure gauge and digital multimeter are not exhaustive; still they go a long way to get optimal results from your non-contact temperature gauging tool.

Every object radiates thermal energy at temperatures above absolute zero. Measuring the temperature of an object using an optical pyrometer is based on the principle that the thermal radiation from the object being measured is a function of its temperature, and measuring thermal radiation sounds like a very straightforward engineering problem.

But the real world is more complicated. For any particular temperature and wavelength, the energy radiated by a surface is directly proportional to the spectral emissivity of the object. Emissivity is the value associated with a surface’s ability to get rid of heat by radiating thermal energy, and different substances have different emissivities. The value of a substance’s spectral emissivity is a number in the range of from 0 to 1.0, which is the ratio of the energy radiated by object’s surface to the energy radiated by a perfect blackbody at the same temperature. The higher the value, the better the surface is at emitting energy.

In physics, a black body is a substance that absorbs all electromagnetic radiation falling upon it. As it is a perfect absorber it is given an emissivity of 1.0. The laws of thermodynamics developed by Max Planck, and others, specify that it must also be a perfect emitter of radiation, and the energy distribution as a function of wavelength is dependent on the absolute temperature.

In practice, the amount of thermal energy a given object emits is directly related to its temperature, wavelength, wavelength band and a number of other factors such as the surface quality, transparency, reflectivity, absorptivity, angle of observation etc. These factors need to be considered when designing and using pyrometers.

Since a pyrometer is not an absolute instrument, it is necessary to calibrate it against a blackbody to convert the electromagnetic radiance received by the pyrometer to its corresponding temperature. If a pyrometer is used to measure the temperature of an object with unknown emissivity, the reading will not be valid, because the object will emit the electromagnetic energy proportional to its emitting ability and temperature shown by the pyrometer will be lower than the actual temperature.

Thus, to deduce the accurate temperature of a given surface from the radiation it is receiving, an operator has to know the emissivity of the material he is measuring. Usually an emissivity control on the pyrometer allows this value to be set on the instrument being used.

Unfortunately, the main difficulty in the practical use of infrared thermometry is the necessity of measuring the temperature of objects whose emissivity is unknown. The lives of scientists, engineers and technicians who must make precise measurements of temperatures in industrial processes or scientific inquiries would be a lot simpler if every substance, regardless of its composition, surface texture or geometry, would emit the thermal radiation at given temperature independent from wavelength . It would also make life a lot simpler for the designer of radiation pyrometers.

There are many publications that list the emissivity values of various materials. It would be relatively simple if these emissivity figures could simply be used as published. However, sometimes this published data lists both total emissivity and spectral emissivity and it is important to pick the right number. Most metals with clean surface or with thin oxide layer have the emissivity that varies with wavelength and using the total emissivity value will cause a significant error in temperature indicated by the pyrometer (if the wavelength band is not wide enough). In order to reduce the temperature error, the effective emissivity and effective wavelength must be used for pyrometer calibration. In each case, the pyrometer operating wavelength and band data has to be matched with the published spectral emissivity table.

There are also other complications.  The emissivity of an object is not a fixed number. It is continuously changing because of changing surface conditions such as oxidation and recrystalization, and these must be taken into consideration if an accurate temperature measurement is to be made. In most cases, temperature has to be measured under a wide variety of conditions presented by objects such as semiconductor wafers, ceramics, clean metal surfaces, partially oxidized metal surfaces, mixtures of molten metal and slag, and semitransparent objects such as glass with surface qualities varying from mirror smooth to perfectly diffuse.

Unfortunately, a universal method suitable for all possible applications doesn’t exist. However, a number of approaches have been developed to overcome some of these difficulties that will produce reliable and consistent temperature measurements. http://www.roktools.com

With standard single wavelength pyrometers this will often require a certain amount of guesstimation on the part of the operator using the instrument. Rarely is it possible to achieve accurate and repeatable measurements in this manner. The best way to solve typical emissivity problems is to just measure the emissivity. But the emissivity of an object is not easy to measure accurately because it depends significantly on many physical and chemical properties, such as temperature, wavelength, angle, oxidation, and roughness.

Emissivity data can be obtained in number of ways. If the temperature of the object can be measured with a contact thermometer, the pyrometer’s emissivity setting can be varied until it indicates the same temperature, and measurements can then be made of that particular surface using that setting. Any change in the area or surface being measured would require repeating the measurement.

Another technique is to blacken part of the object with soot or special high temperature black paint that will approximate a coefficient of 1.0. The pyrometer measures the temperature of the blackened area, with the instrument set at its highest 1.0 emissivity setting and the temperature is noted. Then the bare surface is measured and the emissivity control setting on the pyrometer is changed until the instrument shows that same temperature. A close approximation of a black body can also be achieved by drilling a deep narrow hole in the object to create what is known as a black body cavity. In this method, the pyrometer must be able to focus into the narrow hole. A reference gold cup pyrometer can also be used to figure the actual object temperature and the pyrometer emissivity adjusted to get the same temperature reading. Finally, a spectrometer and reference source can be used to analyze the emissions of the surface and the pyrometer calibrated accordingly. This is a costly process that usually must be done in a laboratory  Clamp Meters

All of these techniques have drawbacks. In real world processes, the emissivity may have changed by the time it has been determined by these methods and the time of the measurement. Other difficulties with these methods include the fact that they can be time consuming and expensive to carry out, and must be repeated each time there is any change in the object being measured or in the measurement setup. In some cases these methods cannot be used at all if the subject of interest is physically inaccessible.