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CALIBRATION SOLUTIONS
Reference Probes - Semi Standards
http://
www.isotechna.com
-196 to 670°C
Platinum Resistance Thermometers
High Stability Reference Probes
Wide Temperature Ranges
High Stability Platinum Coil Elements
These industrial platinum resistance thermometers are
ideal for field and lab use. Suitable for use as working
standards in Dry Blocks and Liquid Baths or as high
accuracy probes for our range of True Temperature
Indicators.
All the thermometers are metal sheathed and both less
fragile and more affordable than the Isotech range of
true Standard Platinum Resistance Thermometers that
are used in laboratories and are found in our publication
“Solutions for Primary and Secondary Laboratories”.
All the thermometers use handmade coil wound
platinum sensing elements to give high accuracy and
low drift. Isotech’s UKAS accredited lab can calibrate to
the smallest of uncertainties.
Calibration should be specified to suit the particular
operating range and application. Isotech can advise on
which service is appropriate to match the temperature
range and application.
Universal Specifications
Ro 100Ω ± 0.05 Ω
Alpha 0.003850 ± 0.000005
Standard IEC 60751
Stability 0.010 Ω/year
Recommended Current 1mA
Self Heating at 1mA 0.004°C
Calibration Optional UKAS Calibration at extra cost.
See table for typical uncertainties
Connection Four Wire
After manufacture all Isotech
Semi Standard PRTs are thermally
pre-conditioned to provide
optimal stability.
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CALIBRATION SOLUTIONS
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Sensing Element
n General Purpose Probes
Sensing Element
Sensing Element
Model Range Diameter Length Sensing Handle Cable Application
(A) Length (B) (C)
935-14-61 -50°C to 250°C 4mm 300mm 6mm 19 x 30mm 2m PTFE Fast Response, Low
Stem Conduction
935-14-13 -196°C to 250°C 6mm 350mm 25mm 19 x 30mm 2m PTFE Low Temperature
935-14-16 -100°C to 450°C 6mm 450mm 25mm 19 x 30mm 2m PTFE General Purpose
935-14-72 -50°C to 670°C 6mm 375mm 25mm No Handle 2m PTFE Fits Jupiter / Gemini
Carry Case
935-14-98 -50°C to 350°C 4mm 300mm 8mm No Handle 2m PTFE Low Stem Conduction
n Angled Probes - angled head provides maximum clearence at top of calibration bath
Model Range Diameter Length Sensing (C) Cable Application
(A) Length (B)
935-14-82 -50°C to 250°C 4mm 210mm 6mm 50mm 1.5m PTFE Europa - Venus - Calisto
935-14-85 -50°C to 250°C 6mm 420mm 25mm 35mm 0.54 m PTFE Oceanus-6
n Working Industrial Standards
These thermometers use premium grade wire wound elements to IEC-751 and the same internal construction as our working
Standard SPRTs. The 95L is optimised for low temperature with minimum stem conduction. The 95H is optimised for high
temperature operation. Both models employ strain free construction.
Model Range Diameter Length Sensing Handle Cable
(A) Length (B) (C)
935-14-95L -200°C to 165°C 6mm 480mm 25mm 19 x 30mm 2m PTFE
935-14-95H -80°C to 670°C 6mm 480mm 25mm 19 x 30mm 2m PTFE
Termination Options
Bare Wire (BW)
TTI suit TTI-1 to TTI-7, TTI-b – suits TTI-22
DB Connector for Dry Block Calibrator Site Indicator
How to Order
Please Specify Model Type and Termination Option
(for example 935-14-13/BW)
Please state whether UKAS Certification is required
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CALIBRATION SOLUTIONS
Typical Uncertainties of PRT Semi Standards with Range
Resistance at 0°C
Temperature Uncertainty mK
935-14-95H*
Model 935-14-61* 935-14-72 935-14-95H*
935-14-95L* 935-14-13 935-14-13* 935-14-16 935-14-72
-196 25 N/A 25 N/A N/A
-80 20 N/A 20 25 25
-50 15 15 15 20 20
0 10 10 10 15 15
50 10 10 10 15 15
156 10 10 10 15 20
232 N/A 15 15 20 25
420 N/A N/A N/A 40 40
550 N/A N/A N/A N/A 50
660 N/A N/A N/A N/A 50
*Preferred Models
The above uncertainties do not include long term drift
Typical Stability of correctly used semi standard is 0.01°C/year at 0°C
Actual uncertainty of a probe determined at time of calibration
ISOTECH
I though that you might like to see the calibration history of one of our
Isotech have generated a long history of many of our
semi-standards.
Here are a few documented facts:
The 935-14-95 model has the widest temperature range
and in consequence is likely to suffer the largest changes in
characteristics.
Guy Snelling sent the following email about the 935-14-95.
UKAS Calibration
available for these systems
International Traceability - Best Practice
probes from the past 12 years.
You may recall that we purchased this probe to use as a laboratory
standard when our company was still young. This particular probe is
still in daily use and is regularly taken to 600°C in our dry block
calibrator. While we handle it with care, being in daily use for 12 year it
has take the occasional mild knock and accidental abuse - I believe that
it was even taken to close to 700°C once, although I wasn’t involved so I
can’t testify to the temperature reached.
You’ll see from the attached history of the calibration by our NMI that
the probe has remained stable and accurate, and bearing in mind the
daily variations in temperature that it has undergone, these results are
testimony to the high quality of this product.
John, you are to be congratulated on developing and producing such a
ne measuring instrument, and feel free to use us as a product reference
any time.
Kind regards,
Guy Snelling
Temperature Metrologist
InterCal (South Africa)
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