Seeing is not always believing
September 1st 2004 Scott Williams of Raytek UK/Ireland makes the point that meaningful thermal inspections require more than just a pretty picture
There are two types of inspection methodologies applied to temperature measurement in preventive and predictive maintenance qualitative and quantitative inspections. When used together, you can evaluate equipment condition more effectively.
Qualitative inspections provide an indication of equipment status, and help you visualise their condition. Thermal imagers are ideal qualitative inspection tools, because they literally show you the faults affecting operating quality, namely the presence and location of hot spots. The resulting thermal images are a quick indication of whether equipment is working or not working and document where future inspections and eventual repair work should be concentrated. As a rule, the majority of the equipment in most plants and facilities can be sufficiently evaluated, problems identified, and appropriate corrective action taken using such qualitative inspection tools.
However, simply finding the heat does not necessarily mean that a problem is present. By conducting qualitative temperature inspections only, you may assume that higher-than-normal temperatures mean something bad. But this is not always the case. To properly evaluate the presence of hot spots, you need to know the operating load and acceptable heat ranges for those loads, which are specified by manufacturers of various equipment. In this case, accurate evaluation requires more than a pretty picture you must be able to measure exact spot temperature values. Even a small temperature difference of 5 to 10 degrees can mean a major problem. Qualitative inspection methods alone cannot always indicate such slight temperature variations. This is where quantitative temperature inspection enters the picture knowing the precise temperature or temperature distribution is in some cases an absolute decision-making requirement.
With tools, such as handheld infrared thermometers, you can quickly and accurately measure small variations in surface temperature, taking into account all the variables of proper temperature measurement, such as emissivity and reflected temperature. Most models available on the market also feature temperature comparison, analysis and reporting capabilities. When used together with qualitative tools, such as thermal imagers, you can make sound decisions about scheduling corrective maintenance activities and following up on repairs in the plant. On the one hand, qualitative inspections show you that potential problems may exist; on the other hand, quantitative inspections tell you exactly how severe the problem is with an absolute temperature value.
Naturally, the ideal solution for maintenance is to use an inspection tool that combines both methodologies, which is exactly what some high-end thermal imagers currently provide. Unfortunately, this capability in addition to other high-end features, has, up until now, carried a relatively high price tag. However, Raytek, is giving a new form to thermal imaging by introducing an affordable thermal imager with just the right set of features for professional qualitative and quantitative inspections.
With a list price of only 6995 + VAT, the new Raytek ThermoViewTM Ti30 is the only thermal imager in its price category to provide simultaneous thermal imaging and spot temperature measurement, featuring the same simple point, shoot and read operation of an infrared thermometer. ThermoView Ti30 provides quick, smooth scanning, high image quality, as well as adjustable emissivity and reflective temperature compensation for high accuracy within a measurement range of 0 to 250C.
Up to 100 images and temperature data can be stored in the unit and quickly transferred to a PC using the convenient docking station provided with the unit, that enables data download at the push of a button. User-friendly InsideIRTM software is also provided with the ThermoView Ti30 for easy thermal analysis and report creation. Using the software, it is possible to click on various points of thermal images to see the corresponding spot temperature. Users can also view histograms of temperature distribution within an image.
Even at a more affordable price, perhaps combined thermal imaging and spot temperature measurement is not what you are after just yet, but you still require a form of quantitative inspection with documentation capabilities. Such a temperature inspection tool is also available from Raytek, called the PhotoTempTM MX6. It combines a precision infrared thermometer, for accurate non-contact surface temperature measurements from minus 50C to 900C, plus a digital camera for photo documentation and inspection verification. Simply point the unit at the target, pull the trigger and see real-time temperatures, plus maximum, minimum, average and differential values on the lcd. Hi and low alarms can be set by the user, triggering a snapshot of targets outside the acceptable temperature range. Up to 100 images can be stored in the unit, which show the measurement spot marked by a circular laser along with temperature, date and time, then downloaded to a PC for location naming and easy inclusion into emails and reports. Such an inspection tool is practical for following up on routine inspections and thermal imaging surveys to check and re-check repair status. More articles from Raytek (A Fluke Company): | 
