Building and Maintenance
| Infrared inspections for building and facilities maintenance |
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| Written by Ken West, Fluke Ltd (UK), 2007 | |
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Ken West, UK Regional Marketing Manager - Industrial Tools of Fluke (UK) Ltd, explains how infrared temperature measuring can help to locate problems lurking behind the scenes of buildings. Why are temperature inspections important?How does the infrared technology work? Surface temperature can tell a lot about a building's structural elements, plumbing installations, and HVAC and electrical systems. Problems that are otherwise invisible to the naked eye are suddenly clear when looked at through an infrared lens. Air leakage, moisture accumulation, blockages in pipes, structural features behind walls and over-heating electrical circuits can all be detected with handheld infrared thermometers and thermal imaging cameras. By scanning surfaces with such inspection tools, temperature variations can be quickly located: these are often indications of underlying problems, and they can be documented with detailed images in reports when using the best troubleshooting equipment. Pinpointing potential sources of problems also saves valuable inspection time and leads to repairs of only what needs to be fixed. Repeated temperature measurements of the same targets can determine whether repairs were successful and will help anticipate future repairs. Infrared thermometersInfrared thermometers measure the infrared energy emitted from surfaces and convert the information into a temperature reading. They are easy to operate by simply pointing the instrument at the target, pulling the trigger and reading the temperature value. And because measurements are taken at a distance, instead of having to touch the object with a probe, temperatures can be checked on equipment that is operating and in hard-to-reach spaces, safely and without special setup. Laser sighting helps the selection of small targets from optimal distances in low light and in tight spaces.  Figure 1. Thermal surveys canidentify and establish anomalies within buildings. Thermal imaging camerasThermal imaging cameras are another kind of handheld infrared temperature measurement tool. These devices immediately indicate the hot and cold spots in the form of thermal images, again from a safe distance. Traditionally, the high price tag of thermal imagers has been prohibitive, leading many facilities to outsource thermography inspections only once a year. However, new lower-cost high-performance cameras make it possible to bring thermal imaging in-house. Thermal surveys can identify and establish the extent of thermal anomalies within new or existing buildings. The following are examples of thermal imaging applications: Inspecting electrical systemsRegular inspections of electrical installations should be conducted at full load to identify potential problems, such as loose connections, load imbalance and overloads, which, when not attended to, can lead to outages, equipment damage and safety risks including fire. Unusually high temperatures may highlight potential electrical problems but they will probably not determine the cause of a failing component. Inspection procedures should recognise this and identify the next stages in troubleshooting a particular problem e.g. the use of power quality tools, clamp meters and digital multimeters (DMMs). Some examples for electrical systems:1. Electrical connections Whatever the loading on a circuit, vibration, fatigue and age cause the loosening of electrical connections, while environmental conditions can hasten their corrosion. All electrical connections will, over time, follow a path toward failure. A loose, over-tight or corroded connection increases resistance at the connection and since increased electrical resistance results in an increase in heat produced, a thermal image will detect the developing fault before it fails. 2. Three-phase problems Thermal images are also an easy way to identify apparent temperature differences in three-phase electrical circuits, compared to their normal operating conditions. By inspecting the thermal gradients of all three phases side-by-side, electricians can quickly spot performance anomalies on individual legs due to unbalance or overloading. Even a small voltage unbalance can cause connections to deteriorate, reducing the amount of voltage supplied. A severe unbalance can blow a fuse, reducing operations down to a single phase. Overloading or unbalance should then be investigated using other types of measuring instruments such as a clamp meter or power quality analyser. 3. Control panels There are three primary causes for abnormal thermal patterns in supply panels:
4. Transformers A thermal imager can be used to look at external connections, cooling tubes and cooling fans and pumps as well as the surfaces of critical transformers. Overheating in a connection indicates it is loose or dirty, and unbalanced or overloaded phases can be identified. On oil-cooled transformers, if one or more tubes are comparatively cool, oil flow is being restricted and the root cause of the problem needs to be determined. A fan or pump that is not functioning at all will be cold. Checking for missing and damaged thermal insulationInspections both inside and outside structures show the location, shape and intensity of insulation. Recent amendments to Parts L1 (Dwellings) and L2 (Non-Domestic Structures) of the UK Building Regulations, which came into force in 2002, place particular emphasis on insulation continuity throughout the structure. Key to building conformance is that those responsible for achieving compliance must document that infrared thermography inspections have shown that "insulation is reasonably continuous over the whole visible envelope." Pinpointing air leakage pointsUK Building Regulations also place emphasis on greatly reducing air leakage or the uncontrolled movement of air into and out of a building. Both of these can compromise the efficiency of building environmental systems. While best measured with pressurisation testing, thermographic surveys can quickly pinpoint leakage points. Inspections inside and outside of structures, along doors, windows, vents and pipes immediately indicate areas of infiltration and 'exfiltration'. Finding areas of moisture accumulationMoisture intrudes through joints and cracks in roofs, ceilings and walls, and is trapped, resulting in structural rot and mold, some of which may represent serious health hazards. Regular thermographic inspections, inside and outside of structures, are therefore critical to quickly locate cold spots, which are often signs of moisture intrusion. Verifying structural elementsThermographic inspections can also help in the quick location of support beams, pipes, electrical cables and flues in poured walls, floors and ceilings. By simply scanning surfaces, detailed thermal images clearly show the subsurface details. Evaluating building materialsThe performance of interior and exterior wall surfaces, doors and windows under various environmental conditions can be tested to determine their ability to retain or reflect heat and cold. A thermal imager will indicate any energy leaks. SummaryThere are a number of reasons why temperature inspections should be added to the building and/or maintenance inspection checklist. Most importantly, thermographic surveys can save a lot of time and effort in locating existing and potential problems, which can jeopardise not only building performance, but also compliance with building, health and safety regulations. Thermal imagers suitable for industrial maintenance are now affordable. Learning how to use them and how to use analysis and reporting software should prove easy on a suitable training course. Further information Ken West,UK Regional Marketing Manager - Industrial Tools, Fluke (UK) Ltd, 52 Hurricane Way, Norwich, Norfolk NR6 6JB, Tel: 020 7942 0700, Fax: 020 7942 0701, Email: This e-mail address is being protected from spam bots, you need JavaScript enabled to view it , www.fluke.co.uk |
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