Frequently asked questions
regarding Infra Red Viewing materials
1. Why did you decide
to use IR polymers in your general purpose lens?
2. Are the lenses water soluble?
3. Do I need a material that provides
me with a visual Image as well an infra red Image?
4. What are the thicknesses of your
lens materials?
5. Is the IR polymer fit for use
in an IR inspection Port?
6. Is it important to have a high
transmission rate.
7. 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?
8. What Certifications do your IR
windows have?
9. Is your product VPF-75 equivalent
to Hawk -075-C and H-VIR 75 COMET IR windows?
10. Is the IRISS IR inspection window
flame proof?
11. Why is the Knowing Actual transmission
rate so important?
12. Is Your IR window more accurate
than the competitions?
13. 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.
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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).
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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).
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Q. Whar are the thicknesses
of your lens materials?
A. Our standard crystals are 3mm thick,
and the IR polymer is 0.010".
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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.
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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.
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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"
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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!!
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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.
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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.
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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.
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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.
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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.
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