What is IR Thermography?
IR Thermography is the technique of producing pictures called thermograms, from the invisible thermal radiation that objects emit. This is a non-contact means of identifying electrical and mechanical components that are hotter than they should be, often an indication of impending failure, it also indicates excessive heat loss which is normally a sign of faulty or inadequate insulation.
What can IR Thermography do for me?
IR Thermography is playing an increasingly important role in facility maintenance, Non Destructive Evaluation (NDE) and predictive maintenance programs. Thermography detects hidden problems and allows for corrective action before costly system failures. Using IR Thermography can reduce downtime by avoiding unplanned shutdowns, by assisting in the timing and planning of scheduled
maintenance. Thus allowing production time to be increased by maximising equipment availability. Thermographic equipment can also provide valuable data in building maintenance, commonapplications are:
- Evaluation of roofing systems.
- Detection of damp.
- Heating and cooling system evaluation.
- Heating and cooling loss detection.
- Pressure vessel integrity checks.
Predictive maintenance programmes are by their nature very difficult to manage.
Today’s high performance thermographic equipment provides an excellent tool for predicting equipment failure, especially as it has been proved that thermal characteristics change gradually prior to failure. Digital Images from a survey contain reference signals that when decoded by our software allows for more detailed thermal analysis and archiving to a standard database. Image subtraction (where one image can be subtracted from a standard or previously saved image of an object) quickly highlights all temperature differences. More in depth measurement techniques such as histograms or temperature gradients are used in applications where trend analysis is required.
Why Should I use IR Thermography?
Today’s Companies are finding that strict regulations regarding quality, safety and manufacturing standards together with a constant battle to maintain productivity levels can become a drain on precious resources. Managers are becoming more aware of technological advances in equipment, whose practical applications can assist them in meeting statutory and production requirements, thus releasing valuable resources to the company. Current methods in use are slower, labour intensive and in most cases will require some interruption to the process being inspected. IR Thermography is a faster and totally non-intrusive means of inspection and as a result is a less expensive option than traditional inspection methods.
Electrical systems are the most critical items within office buildings and industrial sites. There are considerable benefits to be gained by protecting these systems and reducing unplanned stoppages. Infrared cameras are one of several tools whose usage is on the increase. Recent advances in detector technology and hardware have allowed manufacturers to produce cameras at a price that we could only wish for 2-3 years ago.
Insurance statistics reveal that associated with electrical equipment damage, loose connections
cause 25% of all failures to switchboards, switches, circuit breakers and cables. This type of fault is easy to detect using Infrared cameras, trained operatives can now trace, quantify and trend the fault, this then allows the management of the site to plan repairs during planned stoppages instead of the panic reaction involved when sudden failure occurs, yet alone the possible risk of fire.
Electrical Thermography is the fastest growing area in predictive engineering and we at G M Tech can respond to your needs in any way you require, whether it is supplying you with a full on-site inspection service and consultancy, or providing you with the ability to start your own inspection program through our "TotalIR" package.
We are here to serve you; all you have to do is contact us.
As with electrical inspections Thermography has proved invaluable in a number of industries for mechanical inspections. The principal behind mechanical inspections is that when in operation all mechanical equipment will generate certain thermal patterns, these patterns can change significantly due to friction, lack of lubrication, lack of efficient cooling, etc.
Here at G M Tech we also use vibration analysis with our mechanical inspection regimes, used together they are a very powerful combination allowing diagnosis to be verified by two sources and allowing for much more accurate predictions regarding maintenance shutdowns, etc.
Typical faults that can be identified using thermography are:
- Misalignment, unbalance
- Machine and component looseness
- Damaged shafts, vanes and blades
- Bearing defects, cracks and spills
- Gear defects
- Improper lubrication
- Tank level measurements
Infrared inspections of buildings are now an established field of expertise with specialised training courses available for building envelope inspections, roof inspections, damp and mould identification, etc.
A thermal image makes it simpler to see where insulation is missing or air is leaking in or out of a building. Any object that is not transmitting, generating or absorbing heat will take on the surrounding air temperature, so cold air leaking into a building (or missing insulation on a heated building) will cause cold patches on the wall, floor or ceiling. Conversely, warm air leaking from a building will cause warm patches on the outside of a wall or roof.
In short, the benefits of infrared thermography are:
- Quick inspections
- Results are easily shown visually
- Identifies the areas of air leakage
- Shows thermal insulation defects
- Reveals the efficacy of heating and cooling installations.
There are three key elements of a thermographic building survey that you need to know:
1. Understanding of the construction being inspected.
Construction drawings should be reviewed if available and a full visual examination of the construction completed prior to the start of the inspection. You should also, where possible, consult with the building owner or architect regarding any areas of concern within the building that may require special consideration.
2. Only undertake the survey under suitable environmental conditions.
Infrared surveys can only be completed under the following conditions:
- An external survey must be carried out during the hours of darkness or with little direct solar radiation.
- It is preferable that an internal survey be undertaken under similar conditions, particularly with lightweight construction.
- Sufficient time must elapse to allow heat previously built up from solar gain to be emitted from the building. The time for this to occur varies with the construction, but normally at least three hours is required. Problems with solar gain may limit the effectiveness of thermographic surveys during the summer months.
- No direct solar radiation on each face in the preceding hour.
- Temperature difference across the building enclosure should ideally be 10 K or greater. Standards 5 state: "a minimum of 3/U degrees"; for example, 6 K for a U value of 05 W/m2K.
- Ambient air to internal air difference at least 5 K for the preceding 24 h.
- Ambient temperature within ±3 K during test and for the preceding hour.
- Ambient temperature within ±10 K during the preceding 24 h, or 12 h for lightweight fabric.
- All building surfaces being inspected to be dry. No precipitation immediately prior to or during the survey, this includes mist and fog.
- Wind speeds during the survey not to exceed10 m/s.
3. Correctly record and document all survey data.
What the L2 Regulations Say:
Part L2 of the Building Regulations now demands that all new buildings in England and Wales with a gross floor area above1000 m² must be tested for air permeability.
Most new commercial and industrial buildings will need to comply with a maximum air permeability of 10 m³/(h.m²) of building envelopes. This means that the buildings will need to be tested during construction to ensure that the standard is being met and if not, that remedial works are carried out and the building re-tested.
In England and Wales, Part L2 of the Building Regulations introduced from April 2002, recommends thermal imaging of new building fabric to ensure continuity of insulation. Section 2.1 of the document states:
The person responsible for achieving compliance should (if suitably qualified) provide a certificate or declaration that the provisions meet the requirements of Part L2 (a); or they should obtain a certificate or declaration to that effect from a suitably qualified person. Such certificates or declarations would state:
1. That appropriate design details and building techniques have been used or
2. That infra-red thermography inspections have shown that the insulation is reasonably continuous over the whole visible envelope.
Other regulations apply in different regions, but the principles remain the same.
Air Leakage Testing
Thermography is a quick, easy way of locating air leakage from a building envelope.
Although it cannot quantify air leakage rates, infrared thermography provides the most rapid means to identify unintentional air leakage pathways in a building envelope. The benefits of infrared thermography in this context are:
- Air leakage pathways within a completed construction can be identified and rectified prior to air permeability tests, reducing the risk of repeat testing being required.
- Depending upon the nature of the construction, even a building that meets or exceeds air tightness requirements may still be at risk of deterioration due to air leakage and subsequent condensation. Identifying where air leakage is occurring can be critical.
- Air leakage pathways can often indicate rainwater ingress pathways adding to the potential benefits of an infrared survey.