Noncontact Temperature Sensor Vendors
How do you select a vendor?
Perhaps the best thing to sort the wheat from the chaff is a reference list. But
check it against your needs, both business ones and cost constraints.
you are interested in lowest cost, be certain your specifications are as complete
as possible and test demonstration or sample devices rigorously. "Specmanship"
runs rampant in the noncontact temperature and thermal imager industries. Most
of the problem is due to a lack of agreed technical definitions for the specification
terms used to describe instrument performance. Some test procedures and term definitions
exist in some ASTM Standards and some JIS and VDI/VDE standards from Japan and
Germany, respectively. These are by no means widely used.
The other main contribution
to the problem seems to be the assumption of the part of the unwary user that
the devices behave the way they expect them to. There are no formal third party
reviews nor many agreed testing practices, except in the documents just referenced.
So how do you determine if a device is performing as you expect it to perform,
whether on not that happens to be the literal specification in the manufacter's
literature? It is a vast morass of incomplete specification terms, partial technical
specifications and general user ignorance. Caveat Emptor!!
Bottom line: do
a complete job at your end, which means checking for appropriate standards whenever
ordering and working with your peers to insist on reasonable and adequate standards
for specifying and testing these sensors! The mechanisms are in place, what is
lacking is informed user demand for them.
Temperature Sensor Community website, www.tempsensor.net
has the feature enabling all interested individuals to enter reviews of products
and services. Possibly one way to gain information is to share results openly.
It is not intended as a gripe area. The intent is to collect in one open and freely
accessible forum, results of careful tests by apparently serious users. All entries
are reviewed prior to publication on the Internet. In addition, an open forum
message board has been established to allow users and manufacturers to discuss
the many related issues and findings.
In addition to user reviews, the Community
webite also has a self-service facility for manufacturers to add their own corporate
liting as well as details of new product and personnel news. Again, these inputs
are reviewed for appropriateness and overzealousness.
to Noncontact Temperature Sensor Vendors
Line Scanning Thermometer vendors
are included in this set of listings.
Imaging Service Organizations Many of the organizations that supply contract
Thermal Imaging Services also offer used units for sale at reduced prices. Some
even have arrangements with equipment makers to resell devices. Check these organizations
when seeking a quality Thermal Imager at a bargain price.
Do not overlook these organizations as sources
of expertise in choosing a sensor. Some are closely linked with some equipment
makers and you must weigh their recommendations for partial bias, at least. Some
also run an equipment advertising service for used or refurbished equipment; a
valuable resource for more cost-savings in equipment purchases.
The ratio pyrometer or two
color pyrometers (or two colour thermometers, if you prefer) vendors are included
within the radiation thermometer group of suppliers.
- Fiber Optic Temperature
There's only a start on this page to
help differentiate between contact and noncontact temperature sensor vendors;
but it is a start.
Some vendors are more capable
and/or honest than others, just like in every business. The watch words are, as
always: "Buyer beware", until you build up confidence in their business
ethics and technical abilities (and that of the organization they represent).
There are no standards for
the names of the spot-measuring infrared devices. Most metrologists that work
in this field tend to call them "Radiation Thermometers". Could that
imply, from the enormous variation in names of these devices, that standardization
is non existent or not mature in the noncontact temperature sensor field? Yes,
YEs, YES-there is room for a great deal of work in this area!!
get caught in the spec trap, thinking that you know what the specification on
a data sheet means. Fact is there are not even any standards for the nomenclature
used to describe technical features of these devices, starting with calibration
uncertainty! Manufacturers know (we hope) but don't always tell all. Few agree
in any aspect of their specifications beyond the temperature range of a given
unit. The ASTM in the USA has brought some order to this with Standard E 1256,
but it is voluntary and not required by many buyers, as of 2003.
lack of standards and precise nomenclature in terms of quantitative temperature
measurement (called "radiometrically calibrated devices" by most of
the suppliers) is an obtacle thermal imaging technology needs to overcome to master
many of the more demaning uses such as human body temperature screening and process
monitoring and control. The "Buyer Beware" caution applies doubly or triply with
these devices simply because they are more complex than radiation thermometers,
there is much technical confusion and not a widespread understanding about temperature
calibration and measurement with many of the traditional imager manufacturers.
Most of their attention over the past decades has been in imaging characterization
in terms of contrast.
The entry into
the thermal imager market in the past few years by the top-tier radiation thermometer
companies, who live and thrive on precision and accuracy of IR temperature measurement,
may create some changes and improve this aspect of the business. In addition,
one organization that has attempted to bring some order to the temperature measurement
issue is the Infraspection Institute,
one of the oldest and largest thermography training companies. They have had information
on their website and that of their Symposium Group, IR/Info,
on this issue for the last year, at least. More recently, The Standards organization
of Singapore, known by the acronym SPRING,
has been developing a Technical Standard for basic evaluation of thermal imaging
cameras used in screening humans for possible elevated body temperature as a result
of the SARS scare in early 2003.
you have a requirement spelled out and are sure it is covered by current standards
or by a set of detailed specifications you have developed, are you going to be
using the sensor in a ISO900x production or a process or test that is critical?
Then you will most certainly need a traceable calibration for the devices you
Without it any measurements will have errors that can only be guessed, not
verified, nor ever verified or repeated except by happenstance. Often the last
item on a purchase checklist is the most important, as is this one: Traceable
In their 2001 book, "Traceable Temperatures" (see our References
page) Nicholas and White observe that measurements without traceabilty, are
not measurements at all but effectively some vague effort that, in a critical
analysis, is seen not worth the time and money.
all implies, among other things that there is a test or demonstration of capability
that a unit must pass to be accepted. Even devices that will be used to only compare
two temperatures (measure a temperature difference) need to have some reference
to which they can be re-tested to verify that they are meeting the requirement.
Often simulating the need under true application conditions of measurent can be
challenging and difficult to do and maintain a traceable calibration to within
the desired norms.
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