Why and How to Use Thermal Imagers?

Resource Description

Why Use Thermal Imagers?

Thermal imaging cameras are able to produce a crisp image in the darkest of nights. Thanks to special calibration, some thermal imaging cameras are also able to measure temperatures in a non-contact mode.

All this makes them extremely suitable for a wide variety of applications.

Thermal imaging cameras can help you save money. And even more importantly, thermal imaging cameras can help to save lives.

Industrial

In industrial environments, thermal imaging is used for finding hot-spots that can lead to failures in electrical and mechanical installations. Electrical cabinets and motor control centers are regularly scanned with a thermal imaging camera. By detecting anomalies at an early stage production breakdowns can be avoided and money can be saved.

Thermal imaging cameras are commonly used for inspections of electrical systems and components in all sizes and shapes; for mechanical installations; pipework; refractory and petrochemical installations; tank level detection, etc.

Building

Building professionals look for insulation losses and other building-related defects with a thermal imaging camera. Finding insulation losses and repairing them can mean huge energy savings.

Thermal imaging is an outstanding tool to locate building defects, such as missing insulation, moisture detection, thermal bridges, locating leaks in radiant floor heating systems, plumbing, electrical faults, etc.

Thermal imaging cameras for building applications are powerful and non-invasive tools for monitoring and diagnosing the condition of buildings, solar panels, and windmills. With a thermal imaging camera, you can identify problems early, allowing them to be documented and corrected before becoming more serious and more costly to repair.

Thermal imagers:

• Are as easy-to-use as a camcorder or a digital camera
• Give you a full image of the situation
• Identify and locate the problem
• Measure temperatures
• Store information
• Tell you exactly what needs to be fixed
• Help you find faults before real problems occur
• Save you valuable time and money

How to carry out thermal inspections (industrial applications)

Here are some tips for industrial application:

1. Define the task

List all of the equipment you want to monitor. In many corporate settings, such a list is already available; all you have to do is to eliminate the items on the list that are not suited for thermal imaging inspections.

The next step would be to prioritize the list. Most companies keep maintenance and production records. These records will show which equipment is most prone to failure and therefore deserves close scrutiny. Also, take into account the direct consequences of failure; vital equipment should be monitored more often and more closely than equipment that can be temporarily out of order without impeding the functionality of the entire process.

Based on this information, you can start setting up the schedules for the thermal inspections. But you’re not ready to start yet. There’s another vitally important step you should take first.

2. Perform a baseline inspection

Before you can actually start diagnosing problems in your equipment, you need reference material. We, therefore, advise you to take thermal images of all of the equipment you aim to inspect. This should be done during normal operation. Please note that in some cases, you might have to capture multiple thermal images of one piece of equipment, especially if it has key components or subsystems that are prone to failure.

These images will serve as your baseline reference material. It is, therefore, very important to document your baseline inspection very well. The report of your baseline inspection should include the methods you used, such as the emissivity and reflection settings for each piece of equipment, but also the exact location description of each thermal image.

Once you have a database of baseline images, you can determine what temperatures are acceptable for each piece of equipment and set a temperature alarm threshold. It will enable the camera to give an alarm if any part of the thermal image gets too hot, which helps you to speed up your future inspections. Record this temperature alarm for future use.

All of this information will help you to determine whether there is something wrong with the equipment during later inspections.

3. Start inspecting

If all of the baseline temperature measurements have been performed and well documented, you can start inspecting the equipment. You should have a list with pieces of equipment that need to be checked and a schedule for the inspections that take into account both how prone the equipment is to failure and the impact of possible failure on the entire process.

If a piece of equipment is up for a thermal inspection, simply load the correct temperature alarm and start inspecting. If the alarm goes off, that indicates that this piece of equipment requires further investigation.

Please note that the temperature alarm doesn’t mean that it is not necessary to take a close look at the thermal images, however. The thermal imaging camera operator needs to have an in-depth understanding of both the physics of thermal imaging technology and of the workings of the equipment that is inspected. To illustrate this, you should take a look at blown fuses and cooling systems with a restricted flow of coolant. These are just two examples of problems that lead to cold spots instead of hot spots. We, therefore, advise you to familiarize yourself with all of the equipment failure related heat signatures.

4. Analysis and reporting

When all of the equipment has been inspected, it is time to return to the office to do the analysis of the images and to summarize the findings in a report. But it does not end there. A proper thermal imaging camera’s reporter allows you to accurately track the thermal performance of your equipment over time with easy-to-understand charts and graphs. This information will help you to predict when equipment will need maintenance.

How to carry out thermal inspections (building)

So the thermal imaging camera has been delivered, and the inspection can begin. But where do you start? In this section of the guide, some thermal imaging methods will be presented in order to get you going.

1. Define the task

Start the assignment by interviewing the client about the conditions of the building. For instance: has there been a recent increase in energy usage? Is it cold inside? Is there a noticeable draft? Then determine both the inside and outside temperature and make sure that the temperature difference is sufficient for building inspections (a difference of at least 10 °C is advisable).

2. Start from the outside

Start the thermographic inspection from the outside. Missing insulation or cold bridges can quickly be found there. It is also important to take thermal images from areas where conditions seem to be all right. It will allow comparing the result with images that show faults to evaluate the extent of the different problems found.

3. Continue inside

The next step is looking at the situation from the inside. This requires thorough preparation, however. To prepare for the interior thermal scan, the inspector should take steps to ensure an accurate result. This may include moving furniture away from exterior walls and removing drapes. It is advisable to do so at least six hours before the inspection, so the insulating properties of furniture no longer influence the thermal readings from the thermal imaging camera. As stated previously, the requirement for accurate thermographic inspections is a large temperature difference (at least 10 °C) between the inside and outside air temperatures. When these conditions are met, the inspector can start scanning every room in the building with the thermal imaging camera. In doing so, the inspector should make sure that he takes accurate notes of where each thermal image was taken, perhaps by marking the location with arrows on a floor plan to show exactly from which angle the thermal images have been taken.

4. Set up an airtightness test

Small cracks and crevices can cause a draft. This is not only annoying, it can also cause severe energy loss. Air leakage can account for up to half of the energy consumed for heating purposes. An airtightness test often referred to as a ‘BlowerDoor’ test can make the smallest cracks visible. The 'BlowerDoor' helps exaggerate air leaking through defects in the building shell. A 'BlowerDoor' system includes three components: a calibrated fan, a door panel system, and a device to measure fan flow and building pressure. The 'BlowerDoor' fan is temporarily sealed into an exterior doorway using the door panel system. The fan is used to blow air into or out of the building, which creates a small pressure difference between inside and outside. A ‘BlowerDoor’ system employs a fan to either suck the air out of the room or blow air into it, causing a pressure difference. In situations where the outside air is colder, the most common method is to suck the air out of the room using the ‘BlowerDoor’. As a result, the pressure inside the room is lower than the outside air pressure; usually, the difference is about 50 Pascal. Due to this pressure difference, the outside air will rush into the room through the cracks that are present. The outside air will cool down the location where a crack is present. This temperature difference will clearly show up in the thermal image as a cold spot or cold area, allowing the operator to accurately locate and map the air infiltration pathway.

5. Analysing and Reporting

When all rooms have been inspected, it is time to return to the office to do the analysis of the images and to summarize the findings in a report.