Cooper-Atkins TTM41 User Manual
Accurate for Life
The same innovative technology we developed for our popular thermocouple instruments
- used by some of the most sophisticated chains in the world - is now available in selected
digital thermometers. With settings stored in a non-volatile memory chip, eld calibration
has become a thing of the past. No “eld” adjusting of calibration settings required.
And no risk of introducing error into the instrument. We are so committed to ensuring
the accuracy of our products that we guarantee it.
DPP400W
Specications
• Waterproof
• Anti-microbial Additive
• Accurate for Life
• Lifetime Warranty
DPP400W Pen Style Digital Pocket Test
• -40° to 392°F / -40° to 200°C
• 2.75” / 7cm Stainless Steel Stem with a reduced tip
for <6 second response time
• Max / Min / Hold modes
DFP450W
TTM41
TTM59
DFP450W Digital Pocket Test with Temperature Alarm
• -40° to 450°F / -40° to 232°C
• 5” / 12.7cm Stainless Steel Stem with a reduced tip
for <6 second response time
• Max / Min / Hold modes
TTM59 Pocket Test Plus™
• -4° to 350°F / -20° to 177°C
• Clock and calendar
• 3 preset timer alarms, for 5, 15 and 30 minutes
• 4.68” / 11.9cm Stainless Steel Stemwith a reduced tip
for <6 second response time
• Max / Min Memory modes
TTM41 Coolit-Rite™ Cooling Validator
• -4° to 302°F / -20° to 150°C
• Timer Range: 6 Hours : 59 Minutes
• 15” / 38.1cm Stainless Steel Stem with
adjustable vessel clip
• Max / Min / Hold modes
Bold NEW
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Products
Eliminate Error - Remove Risk
Cooper-Atkins Corporation • 800-835-5011 • 860-347-2256 • www.cooper-atkins.com
67-856
Setting the record straight
on field-calibration of
digital pocket test thermometers
Temperature measurement using modern thermistors is one of the most
accurate, reliable, and inexpensive methods currently available. These
ch ara cte ris tic s, whe n m arried wit h t oda y’s po wer ful ye t low-c ost
mi cro con tro lle rs, pr odu ce a new g eneration of di git al pocket t est
th e r m o meters t h at fa r e xceed t h e capa b i l i ties o f their l i quid o r
bi-metal ancestors.
A thermis tor is a resis to r that is made to hav e a high tempera ture
coefcient, which means that the resistance of the thermistor changes as
the temperature of the thermistor changes. By producing it to an exact
for mula, the thermistor’s behavior can be accurately predicted an d
represented in a resistance versus temperature table (R/T) which lists the
known resistance value of the thermistor at a given temperature.
The repeatability or drift of the thermistor’s behavior over time varies from
one thermistor manufacturer to another, but is typically in the order of
< 0.05°F per year. In fact, thermistors become more stable over time, so
most of the drift occurs within the rst six months of use.
In a digital thermometer, the microcontroller is programmed with the
thermistor’s R/T characteristics in a look-up table. The resistance of
the thermistor is measured using precision timing circuitry, and is then
“looked-up” in the table to determine the measured temperature. Any
difference between the measured temperature and actual temperature,
kno wn as cal ibration offset, is programmed int o the mic rocontrolle r
memory during the manufacturing process.
Per iodic checking of the thermometer accuracy is r ecommended as
standard practice to satisfy certain governmental regulations and for
HACCP programs. Over its lifetime, the digital thermometer may exhibit
some minor accuracy shift, due in part to environmental variations, and in
part to normal aging of the components used. However, any such shift will
be far smaller than the tolerance allowed on the accuracy specication,
and as such, it will not be necessary to make adjustments to calibration
once the thermometer is in service.
Thoughts on eld calibratable thermometers...
“Field calibration” is a feature found in a number of digital thermometers
marketed today. This feature allows the user to reset or adjust out the
expected error / drift the thermometer may have over time. While this
may sound like a useful feature it could actually introduce more error at
critical test temperatures!
Here’s why…
Digital thermometers calibrated in the eld by the user are done so using
a single test point, usually 32°F (0°C). This temperature is used because
an ice bath is usually the easiest, if not the only, way to obtain a known,
stable temperature in the eld without investing in laboratory calibration
equipm ent. When a dj ustment is perform ed on a “field calibra ta ble”
thermometer, the resistance versus temperature table (R/T) is adjusted
up or down automatically when the user resets their thermometer and
removes any error at the 32°F calibration point. By design, this shift in the
tab le or resistance / temperature curve is applied across the ent ire
temperature / resistance curve and therefore is applied to all measured
temperatures.
The rst potential for introducing error during eld calibration has to do
with shifting the curve within the thermometer’s microprocessor and the
fact that any “drift” a thermistor exhibits is not necessarily equal at all
temperatures.
For example, a thermometer utilizing an inferior sensor may drift by +2°F
at 32°F (reads 34°F in a 32°F bath) but may not have drifted at all at a
higher tempera ture t est poin t. I t could read 13 8°F at a cr it ical t est
temperature of 140°F for instance, while being off by +2°F at 32°F. During
“eld calibration” this thermometer will be reset so that instead of reading
34° F, it will read 32°F in the ice bath. The user is satisfied that their
th e rmom eter is n o w “dea d -on” a t 3 2°F. Un f ortu n atel y t his sa m e
thermometer will now read 136°F at 140°F, a more critical temperature
for food safety! Calibrating at a single point shifts the entire resistance
versus temperature relationship by the same two degrees across all
temperatures. The user would have no way of realizing this unless they
were able to test at other critical temperatures.
A second potential for introducing error during “eld calibration” is from
an improperly constructed ice bath. The improperly made ice bath (bath
made with too much water and not enough ice) will contribute to error
as the test temperature, assumed to be 32°F, is actually a few degrees
warmer. In this case it is possible for a thermometer without any error (at
any temperature) to be reset so that it reads 32°F when the actual test
temperature is say 33°F or 34°F. This introduced error would also now
affect all other measured temperatures.
Per iodic checking of the thermometer accuracy is r ecommended as
standard practice to satisfy certain governmental regulations and for
HACCP programs. Over its lifetime, a digital thermometer may exhibit an
accuracy shift, due in part to environmental variations, normal aging and
the quality of the components used. However, products designed with
higher technology components will experience accuracy shifts far smaller
than the tolerance allowed on the accuracy specication. As such, it will
not be necessary to make “adjustments to calibration” once the thermometer
is in service.
While accuracy checks using a properly constructed ice bath remain the
recommended in eld method, users need to recognize the limitations of
single temperature point calibration. Instrument accuracy, stability and
guarantees over time can only be achieved through superior design and
use of high quality and robust components and sensors.
U.S. Food and Drug Administration
Center for Food Safety & Applied Nutrition
Food Code
Chapter 4 Equipment, Utensils and Linens
4-502.11 Good Repair and Calibration.
(A) UTENSILS shall be maintained in a state of repair or condition that
complies with the requirements specied under Parts 4-1 and 4-2
or shall be discarded.
(B) FOOD TEMPERATURE MEASURING DEVICES shall be calibrated
in accordance with manufacturer’s specications as necessary to
ensure their accuracy.
(C) Ambient air temperature, water pressure, and water TEMPERATURE
MEASURING DEVICES shall be maintained in good repair and be
accurate within the intended range of use.
Committed to Innovation for Over 120 Years...
Cooper-Atkins Corporation • 800-835-5011 • 860-347-2256 • www.cooper-atkins.com
67-856
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