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The Model 526 is a portable low temperature calibration source designed for both laboratory and field use. It generates controlled temperatures from -115°C to 50°C with ±0.03°C stability, making it one of the most capable sub-ambient dry block calibrators available. Built on Isotech’s 45+ years of temperature metrology expertise and the pioneering legacy of the Model 525 (the world’s first -100°C dry block), the 526 addresses calibration challenges that conventional ice baths and dry blocks cannot reach.
Who Needs the Model 526?
Calibration professionals working with sensors deployed in ultra-low freezers (-70°C to -80°C), pharmaceutical cold chain storage, bio-banking, aerospace environmental testing, food-processing flash-freeze systems, and industrial cryogenic processes. If your sensors operate below -40°C, the 526 is built for you.
Free Piston Stirling Cooler (FPSC) Technology
Unlike liquid-nitrogen-based systems that require consumable cryogens, the 526 uses a Free Piston Stirling Cooler for reliable, repeatable deep cooling. Plug it in, set your target, and reach -115°C in approximately 85 minutes from a 23°C ambient start. Heating back to 50°C takes the same time. No gas bottles, no dewars, no ongoing consumable costs.
Accuracy and Uniformity
Display accuracy is ±0.5°C across the full range, with 0.01°C resolution for precise set-point adjustment. When paired with an external reference thermometer, system accuracy improves to ±0.05°C—dependent on reference thermometer calibration status and insert configuration. Radial uniformity is better than 0.03°C, and axial uniformity is 0.15°C at -100°C. The 526 meets the requirements of EURAMET cg-13 for temperature block calibrators, giving you traceable, audit-ready results.
Engineered Inserts for Cryogenic Performance
Each 526 ships with a Type A insert (6 pockets: 2 x 4.5 mm, 2 x 6.4 mm, 1 x 8.0 mm, plus a reference well). The 130 mm pocket depth plus 50 mm insulating cap provides 180 mm of effective immersion. Inserts are optimized for ultra-low operation with controlled thermal mass and a surface treatment that minimizes probe sticking at cryogenic temperatures. Alternative inserts (Type B, Type C, validation, and blank) are available, as well as custom-drilled inserts for specific probe diameters.
Portable and Field-Ready
At just 12 kg (16 kg with the included carry case), the 526 is designed to go where the calibration work is. Environmental protection features limit moisture ingress and ice formation during operation at cryogenic temperatures. An RS-232 interface supports remote operation and integration with I-Cal Easy calibration software for automated calibration, data logging, and certificate generation.
What’s Included
Each Model 526 is supplied with a carry case (pull-out handle, integrated wheels), Type A insert, insert removal tool, touchscreen stylus, and traceable calibration certificate. An RS-232 communication cable is available as an optional accessory (P/N 935-16-112).
A Complete Calibration System
Pair the 526 with Isotech reference thermometers, reference probes, and I-Cal Easy software for an end-to-end low temperature calibration workflow that no other manufacturer can match.
| Model |
526 |
| Temperature Range |
-115°C to 50°C (at 23°C ambient) |
| Stability |
±0.03°C (measured over 30 minutes, full range) |
| Display Accuracy |
±0.5°C (full range) |
| Accuracy with External Reference |
±0.05°C (dependent on reference thermometer and insert) |
| Display Resolution |
0.01°C |
| Stabilisation Time |
~15 minutes |
| Cooling Time |
23°C to -115°C in approximately 85 minutes |
| Heating Time |
-115°C to 50°C in approximately 85 minutes |
| Immersion Depth |
130 mm pocket + 50 mm insulating cap = 180 mm effective |
| Cooling Technology |
Free Piston Stirling Cooler (FPSC) |
| Interface |
RS-232 |
| Power Supply |
100-115V or 200-230V, 50/60 Hz |
| Power Consumption |
Approximately 575W |
| Recommended Ambient |
21°C to 25°C |
| Operating Environment |
15°C to 60°C, ≤80% RH non-condensing |
| Radial Uniformity |
<0.03°C |
| Axial Uniformity |
0.15°C (measured at -100°C) |
| Axial Uniformity [1] |
0.45°C (measured at 40°C) |
| Standard Insert (Type A) |
6 pockets: 2 x 4.5 mm, 2 x 6.4 mm, 1 x 8.0 mm, 130 mm deep. Type B, Type C, validation, blank, and custom inserts also available. |
| Weight |
12 kg (16 kg with carry case) |
| Standards Compliance |
Meets EURAMET cg-13 requirements |
[1] Represents worst-case vertical gradient over 25 mm
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Literature
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| 526 Low Temperature Calibration Source Datasheet |
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