analyzing your findings

Analyze your findings…..How accurate are your readings and why?

Many people are not aware that the detector in an infrared camera actually only reads electromagnetic radiation it receives in a specific range of wavelengths. In order to display this in a useful reading the camera makes several calculations in order to convert the actual data to a temperature. The emissivity and transmissivity (sometimes depending on the camera manufacturer) have to be manually entered into the camera’s menuif this value is entered incorrectly the actual temperature will be exponentially different (see Stefan-Boltzmann’s Law) than the displayed temperature. The old saying of “well as long as it is consistently wrong the change will be noted” is not entirely correct either, as the difference between phases will also be exponentially wrong. The error is going to be worse as the temperature rises – if the differential between the measured temperatures is significant then the displayed temperatures could be significantly different!

So that phase imbalance that looks like it is only a couple of degrees different could actually be upwards of 30 degrees! The visual setup of the camera could be the only other way of determining the severity of a potential defect. As anyone who has spent some time looking through a camera will tell you the visual component can be significantly altered (both to make things look better than they are as well as to show “elevated” differentials.) Depending on the level, span and range setup on the camera it would be very easy to miss a severe problem.


With this in mind it is easy to see why there are so many infrared problems that aren’t caught. In order to ensure that our customers “See What You’ve Been Missing”, all IRISS polymer based windows utilize the same grade and thickness of polymer, so that if you have correctly setup your camera for one IRISS window you can know without any doubt that it is “calibrated” for all IRISS windows. Our Fixed And Stable Transmission (FAST) is exactly what the name implies – unchanging! The ambient temperature outside, length of time in the field, relative humidity or barometric pressure have no effect on transmission rate and therefore no effect on your readings!

formula to determine field of view

The Formula for Determining Field of View Using any Infrared Camera

Every infrared camera defines its Field of View (FOV) across a horizontal/vertical axis.

You have two ways to determine the Field of View (FOV) on your camera:

  1. You can calculate the FOV using the formula: 2 x the tangent of ½ the angle x distance
  2. You can measure (and “map out”) the practical FOV with a quick field test to check your math!

The practical FOV test is quick, relatively easy, and in no way requires a scientific calculator!

The practical FOV test is a simple method to determine what can be seen at set distances with your camera, the lens, and IR Windows.

  1. Find a long workbench, counter-top or a 6 foot folding table. Layout a piece of plain paper along the entire length of the table.
  2. Set the camera on the table and mark a “zero” line across the table width. This zero line should be far enough on the table so that the camera cannot accidentally fall off the table. The zero line is where the camera lens touches the line.
  3. Draw a straight line the length of the paper along the center.
  4. Label this line with 6 inch increments marked out from the zero line.
  5. Label the lines from 0 to 36 inches. You can go further if you have a panel depth deeper than 36 inches, but usually 36 inches is sufficient.
  6. Place the camera lens at the zero line with the straight line going down the center of the paper in the middle of the camera lens.

Now, it is time for a coffee break. Not really, you need two heat sources. Some people use coffee cups – good excuse for a break.  You can use any known heat source. Some people use hot plates if they are in a lab, a griddle, or you can purchase inexpensive candle warmers.

  1. Place the two heat sources at a distance from the camera that is typical of the targets you will monitor. For example, if your targets are 18 inches from the panel, then place the two heat sources at the 18 inch mark.
  2. Move one heat source from the center until it appears just inside the edge of the image in the camera display.
  3. Move the other heat source in the opposite direction until it appears just inside the camera display on the other side.

The distance between your two heat sources is the maximum FOV using your camera and lens. At the defined distance.

  1. You can draw a line from each side of the camera lens at the zero line to the heat source on the same side. This gives you the FOV for any distance from the zero line to the heat sources.
  2. If you are using an IR Window, subtract the camera lens diameter from the FOV. Next add the diameter of the IR window. This gives you the Maximum Horizontal Window FOV. For example, you have a FOV of 8 inches, at 18 inches on the center line. The camera lens is 1.75 inches. The camera FOV is then 6.25 inches. If you are using a 4 inch IR Window, then add 4 inches for a total Maximum Horizontal Window FOV of 10.25 inches.

You should repeat the above process with the camera lying on its side to determine the Vertical FOV.

When finished, roll up your map and save it for future reference.

You can create a table for the distances along the center line and the Horizontal and Vertical FOV for different window sizes in your plant.


What Certifications Apply to Infrared Windows?

Years of industrial manufacturing experience have given technicians a trust that the minimum requirements necessary for certifying a product to UL standards are usually enough to ensure safe and reliable operation. In the case of infrared windows this is not necessarily true.

UL 50V is the only standard defining infrared windows. It verifies that the window provides a means for passage of infrared radiation. The scope of the standard specifically states that meeting the requirements for this standard do not assure the window is suitable for use in any application and that suitability for continued use requires additional evaluation as to the performance characteristics necessary for the installation. It simply verifies that the window passes infrared energy at an unknown transmission rate. Some of the other certifications which are more detailed in defining the functionality necessary and more importantly the safety aspects required before attempting to modify an electrical enclosure in any way are described below.

UL/NEMA 50E: Environmental standards which apply to electrical enclosures intended to be installed and used in non-hazardous locations as follows: enclosures for indoor locations only, Types 1, 2, 5, 12, 12K, and 13; and enclosures for indoor or outdoor locations, Types 3 and 3R.

UL 508: These requirements cover industrial control panels intended for general industrial use, operating at a voltage of 1500 volts or less. This equipment is intended for installation in ordinary locations, in accordance with the National Electrical Code, ANSI/NFPA 70, where ambient temperatures do not exceed 40°C (104°F) maximum.

UL 746C: A standard to test performance of viewing optics. This standard identifies the ability of a window to withstand impact and flame.

UL 1558: A standard covering viewing panes and IR windows fitted into metal-enclosed low-voltage (<600V) power circuit breaker switchgear assemblies. This standard covers low voltage assemblies and allows the impact resistance of the assembly to be tested with the window closed as the pass criteria is that you should not be able to pass a ½ inch diameter rod through the window or cover.  IRISS is the ONLY manufacturer that can pass this test with the covers open as the standard requires that the IR window should not crack, shatter or dislodge which is a requirement that crystal IR windows cannot meet.

IEEE C.37.20.2 section a.3.6: This IEEE standard and test procedure for viewing panes mounted in electrical equipment with ratings above 1kV and requires viewing panes to withstand both impact and load tests.  Unlike UL this does not give any dispensation for material composition of the IR viewing window or whether or not covers are fitted.  The test is simple, it requires that both sides of the IR viewing window are subjected to the impact and load and that neither side can crack, shatter, or dislodge…  Again this is a requirement that crystal IR windows cannot meet.

Lloyds of London Type Approval: Lloyd’s Register Type Approval is an impartial certification service providing independent third-party “Type Approval” certificates attesting to a product’s conformity with specific standards or specifications, and verification of an appropriate production quality system. It is based on a design review and type testing or, where type testing is inappropriate, a design analysis. There is growing international awareness of the importance of third-party certification.

ABS Design Assessment: The intended service location and environmental ratings for the component are verified by engineers verifying the validity of the testing performed on a component before the design assessment certification process in marine and offshore electrical equipment is completed.

Arc Rating –  An arc rating can only be given to a completed assembly and not to a single component within that assembly. Electrical cabinet designs and dimensions are infinite and we therefore CAN NOT or MUST NOT use the data from one cabinet design to another design unless they are identical in every way.

DNV – DNV Certification is awarded for marine and offshore applications and allows preventative maintenance on electrical equipment in these vertical markets. DNV covers Rules for Classification of Ships and Offshore Standards (vessels, tankers, military and cruise ships, and oil drilling riggs).

CE Mark – The CE mark, or formerly EC mark, is a mandatory conformity marking for certain products sold within the European Economic Area (EEA) since 1985. The CE marking is also found on products sold outside the EEA that are manufactured in, or designed to be sold in, the EEA.

IEC 62271-200 – Provides a controlled arc flash test using 1kV to 50kV metal enclosed switchgear to a voltage of 6kV using a current of 31.5KA for a duration of 0.5 seconds to determine the amount of pressure and heat installed components on switchgear can survive and maintain integrity.

This is the reason why components can NEVER carry a generic arc rating and must be subjected to standard industry tests to confirm they meet the mechanical strength and environmental properties for electrical cabinets and assemblies to which they are being fitted.

IRISS CAP and VP series windows are certified to all of the standards mentioned above. As a manufacturer of industrial grade products our windows have completed more testing on than any other infrared window manufacturer. If we can’t meet the requirements of an application we innovate until we can meet the requirements.

IRISS products were conceived by thermographers, to assist with safety and efficiency of industrial inspections. The fact that our products are capable of withstanding an industrial environment should come as no surprise. Only the physical characteristics of available materials limit what the team at IRISS is willing to do to be the solution provider for our customers.

Helping you “Save Time, Save Money and Stay Safe” is what it is all about.