IR Viewing Material FAQ's
Frequently asked questions regarding Infra Red Viewing materials
- Why did you decide to use IR polymers in your general purpose lens?
- Are the lenses water soluble?
- Do I need a material that provides me with a visual Image as well an infra red Image?
- What are the thicknesses of your lens materials?
- Is the IR polymer fit for use in an IR inspection Port?
- Is it important to have a high transmission rate.
- What are the actual viewing diameters of your IR windows as I recently used some of your competitors IR windows and found that the actual viewing diameter was smaller than that quoted in their literature?
- What Certifications do your IR windows have?
- Is your product VPF-75 equivalent to Hawk -075-C and H-VIR 75 COMET IR windows
- Is the IRISS IR inspection window flame proof?
- Why is the Knowing Actual transmission rate so important?
- Is Your IR window more accurate than the competitions?
- Can your IR windows be used with any IR camera?
Q. Why did you decide to use IR polymers in your general purpose lens?
A. When I first started to use IR windows I used my competitors products as they were the only ones available on the market, they struck me as being very expensive and fragile, both qualities were very hard to sell to clients!! I therefore decided to investigate what other types of materials were available and what other types of manufacturing techniques could produce a very high quality, safe and efficient IR window that could be easily afforded.
As an ex Automotive testing engineer I had seen many differing types of manufacturing techniques I decided to use Plastic injection moulding as our means of manufacture, after all virtually every auxilary device on electrical switchgear is plastic and it also has the benefit of being non conductive. I then approached UL for a list of UL94 5VA flame retardant plastics and rubbers as required by the UL standard 508A which relates to Electrical Cabinets. We then carried out an extensive and rigorous testing regime on all the listed plastics and rubbers to derive the base materials that suited our requirements and also that of UL.
Once I had completed the window body design I then concentrated on the optics of the IR window, this is the most costly element of an IR window and we had to get it right. The traditional materials that were being used did have there flaws but were suitable to dry stable environments and not suited to industrial or outside applications as they were highly susceptible to thermal shock, impact and humidity, the other materials that we could use again were more expensive and would be difficult to market.
We therefore had to find a material that would first of all be able to resist the majority of environmental issues and secondly be affordable, the ideal material would be a low cost sapphire that transmits IR in the 8 - 14 micron range! Unfortunately this material does not exist so we looked for other alternatives. I had always been taught as a thermographer that IR will not transmit through plastics or glass, this is still true however there are some Polymers that do transmit IR and this is were we started looking.
I decided to use a polymer very similar to that used primarily in IR movement detectors as they were installed in vast numbers in the home and office all around the world . Our rational was that a material that was in use in vast numbers, and thus has been tried and tested in differing types of operating environments, temperatures, etc both internally and externally and would therefore be suitable to test in our application. Below is a statement by the manufacturer of the polymer we use:
Our infrared–transmitting material is also a flexible. It presently offers the least absorption loss in the 8 to 14 µm region of any of the IR polymer materials, the material is ultraviolet stabilized, and has a lifetime of many years in full sun. (In our rooftop testing facility in the full Texas sun, wind and blowing dirt tend to cause damage long before the sun does; we have yet to establish a lifetime, though material which has been on the roof for two years shows no significant UV degradation in either infrared transmittance or physical properties. We also know of at least one instance of a PIR lens array in a passive infrared motion detector that has been used outdoors in Texas for approximately 15 years without a noticeable decrease in performance.)
As you can imagine this gave me a lot of confidence in the material and it had very acceptable transmission rates in both the SW and LW infrared wavelengths, and the best thing about it all is that it was significantly cheaper than any other IR material we tested for this role. We then started our testing regime first of all with SIRA who completed the IP65 and IP2X testing, we then had the UL and ULc testing completed to 508A and 945VA and finally we have just finished our evaluation by Lloyds and now have the only type approved IR window in the world, an achivement of which we are proud.
The current range of products we now offer exceeds all of the original design requirements and our growing list of clients endorse this.
Q. Are the lenses water soluble?
A. The injection moulded plastic lens material is not water soluble. The windows employing these lenses are very durable and have an IP65 rating. Some common lens materials, however, such as Calcium Fluoride (CaF2), Magnesium Fluoride (MgF2), and Barium Fluoride (BaF2) are soluble in water and may diminish or lose their ability to transmit infrared radiation in a moist environment. (see our materials pages).
Q. Do I need a material that provides me with a visual image as well an infra red Image?
A. Our low cost windows are opaque and are therefore no good for visual images, but why do you need a visual image? The vast majority of electrical cabinets are dark inside as they do not have any internal lighting so the ability to look through the window in irrelevant as you will not be able to see anything!! However if the customer wishes to have clear windows we can suggest that you try CaF2 or BaF2 . (see our materials pages).
Q. Whar are the thicknesses of your lens materials?
A. Our standard crystals are 3mm thick, and the IR polymer is 0.010".
Q. Is the IR polymer fit for use in an IR inspection Port?
A. Most definitely yes, how can it not be! The following data taken from the material safety data sheet proves the point, i.e.:
Reactivity Data
• Polymerisation conditions to avoid = None
• Stability = Stable
• Conditions to Avoid = Temperatures above 325 C
• Incompatible materials = Strong Acids, strong bases and strong oxidisers
Fire and explosion Hazards
• Flash Point = Not Applicable
• Auto Ignition = Not Applicable
• Freezing Point = -107 to -135 C
• Soluble in water = No
• NFPA Hazard Classification (0-4) = Flammable = 1 Health = 2
Plus the IR polymer has a transmission rate of 68% at 9 microns which out performs the traditional calcium fluoride window and is flexible therefore is not as susceptible to thermal shock and fracture due to impact, consequently we and our clients believe it to be a great all round general purpose material.
Q. Is it important to have a high transmission rate?
A. All of the materials traditional used in IR windows (all of which we can supply) are listed in our materials pages. The most important thing to remember regarding IR transmission rates is that you must know what the transmission rate and wavelength that your IR window is operating in. It is irrelevant to the measurement whether it is 99% or 50%, as the camera / software will calculate the temperature based on the transmission rate that you put into the calculation, therefore you must be confident that the transmission rate is correct.
Q. What are the acual viewing diameters of you IR windows as I recently used some of your competitors IR windows and found that the acual viewing diameter was smaller than that quoted in their literature?
A. The Actual Viewing Diameters of our IR windows are:
- VP-50 Series = 50mm or 2"
- VP-50 Series = 75mm or 3"
- VP-50 Series = 100mm or 4"
Q. What Certifications does your company and IR windows have?
A. Our Company is an ISO 9001/2000 registered company with the BSI (British Standards Institute) and was recently awarded the IIP (Investors in People) standard. Our products carry the following, we also have the distiction of controlling the whole maufacturing process.
- UL & ULc
- IP65 (fixed Optics)
- IP2X (Grills)
- Lloyds Type Approval
- Investors In People (staff management scheme)
We take quality and safety very seriously as demonstrated by our constant striving to improve our services and our products, I have heard so many times that people would rather pay more for a quality product!! Who said that price reflects, this not always the case and we are living proof of the fact that through good design and a carefull choice of material wonders can be achieved, after all we have the only IR window system in the world to be type approved by Lloyds!!
What price quality and safety? take a look at our prices before you decide the answer to that question!!
Q. Is your product VPF-75 equivalent to Hawk-075-C and the H-VIR 75 COMET IR windows or not i.e. material, window and others.
A. Our VPF-75 is not an equivalent of the H-VIR 75 COMET or the Hawk IR 3" window. The number of each of our ranges indicates the actual viewing diameter. i.e.
- G M TECH VPF-75 has an actual diameter of 75mm or 3"
- H-VIR 75 COMET has an actual diameter of 52mm or 2"
- HAWK-075-C has a actual diameter of 67mm or 2 5/16" (even though it is indicated a 3" in literature!)
We use UL rated plastics and gasket materials that are UL94 flame rated to 5V, we use the low cost IR1 IR material in our standard window but we can provide any material that suits your budget and operational needs. We normally suggest that new clients purchase some of our low cost units for evaluation. All the clients that have tried our new IR window systems have been delighted with the product and the results.
Q. Is the IRISS IR inspection window flame proof?
A. YES the viewport assembly and gaskets have been tested by UL to UL94 5VA, this is the highest rating that can be given to any plastic assembly, and we passed with flying colours. With regards to each optical material that we use they all have their own individual limitations, and are pointed out to the client during the consultation process. We state now and always have that the IR polymers used have a maximum temperature limitation of 100 C, even though the safety data sheet states that the ceiling temperature to be avoided is 325 C.
Our internal R&D testing of the polymers show that they do burn, however they do self extinguish and are completely constrained within the window assembly, and at the end of the tests we are able to replace the IR polymer and re-use the original gaskets etc. This is a test that none of our competitors could replicate as they only offer limited optics and they are bonded into the assembly thus the whole assembly would need to be replaced, when subjected to the same test.
Q. Why is the actual transmission rate so important?
A. All Infrared widows transmit IR energy, this is known as the transmission rate, their is not an instrument on earth that actualy measures temperature, all instruments calculate temperature and IR cameras fall into this category. IR cameras calculate tempearture using a number of variables: Distance, Emissivity, Ambient and background Temperatures and of course TRANSMISSION, when the camera has all these values imput into the thermogram it will the CALCULATE the temperature.
The graph shows how calculated temperature readings change when you vary the transmission rates. The transmission rates were changed from 99% to 50% using the same image. This gave a difference of 11.8 °C.
The significant thing to note other than the temperature difference, is that the calculated temperature increases when the transmission rate decreases, therefore if your transmission rate is too high the calculated temperature is too low!, this will cause real problems if you are using temperature as the means of categorising faults or scheduling maintenance.
Q. Is Your IR window more accurate than the competitions?
A. NO, I have seen this claim made by manufacturers and it is absolute nonsense. As the answer above demonstrates all IR cameras calculate temperature so as long as you know the transmission your calculated temperatures will be the same, regardless of which window you use.
Q. Can your IR windows be used with any IR camera?
A. The answer to this is YES. The most important thing to know is what you require, the type of equipment that you are using and the operating environment and just leave the rest to us. Our general purpose polymer window works with ALL IR CAMERA'S the only considerations that have to be given are to operating environments and the general purpose IR window fits 95% of those.
Global Maintenance Technologies Ltd
+44 (0) 1245 500 460
g-m-tech.com