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Decontamination Process Validation

Temperature Calibration Guidance

Choosing the Right Temperature Calibrator and Reference Probe


There are several key things to consider when purchasing a new temperature calibrator:


As a rule the more expensive the calibrator the better it is. Purchasing a budget heat source and expensive reference probe may seem cost effective for high accuracy, however calibration times will be far longer if the heat source has an inefficient stability range or heating/cooling times.


Heating and cooling in the middle of the range will be quicker than at the very top and bottom of the range. Calibrators with a range starting around 30 degrees generally cool with a fan, and the actual temperature reached will depend on the ambient temperature.


The range within which the true temperature can be expected to fall compared to the temperature displayed. For example, a calibrator with a stated accuracy of 0.1 degree would be expected to be at between 99.9 and 100.1 degrees when the display reads 100.0, while a calibrator with a stated accuracy of 0.5 degrees would be expected to be at between 99.5 and 100.5 when the display reads 100.0. Calibrators with a large temperature range will often give different accuracies between different temperature ranges.


The extent to which the temperature varies over time after the calibrator has determined that stability has been achieved. This is often caused by the heater turning on and off to maintain temperature, and tends to increase the further from ambient temperature as you go. Note that this is different to 'accuracy' as a calibrator can be stable (the temperature does not change) but inaccurate (the true temperature is 10 degrees different to the displayed temperature).

Heating/Cooling Time

How quickly the calibrator reaches stability after heating and cooling, usually given between specific temperature points (e.g 100 to 0, 23 to 140 ect). The time to stabilise generally increases as the limits of the temperature range are reached.

Isotech Fastcal Complete

Jofra ETC 400A

Jofra CTC 155

Jofra ETC400
Isotech Fastcal Complete Jofra ECT 400A Jofra CTC 155
Range -35°C to +140°C +28°C to +400°C -25°C to 155°C
Stability 0.02°C ±0.15°C ±0.04°C
Reference Probe YES ¹ NO ² YES ¹
Accuracy with External Reference Probe ±0.15°C N/A ±0.2°C
Accuracy without External Reference Probe ±0.2°C ±0.5°C ³ ±0.3°C
TQSoft Automatic Calibration YES YES YES
Heating Time (Approximately) Ambient to +140°C
10 Minutes
Ambient to +140°C
4 Minutes
Ambient to +155°C
13 Minutes
Well Sizes 2x 4.5mm
1x 6.6mm
1x 8.0mm
1x 2.0mm
1x 3.0mm
2x 4.0mm
1x 6.0mm
1x 3.0mm
2x 4.0mm
1x 5.0mm
1x 6.0mm
1x 9.0mm
Physical Dimensions Lx W x H 228 x 248 x 143mm 172 x 72 x 182mm 248 x 148 x 305mm
Certificate Provided Traceable Traceable Traceable
Carry Case Provided Soft Case Aluminium Case Aluminium Case

¹ This unit has an in-built independent reference probe so can take advantage of the TQSoft automatic calibration feature.
² Accuracy can be greatly improved when using a compatible reference probe and the TQSoft automatic calibration fetaure.
³ This unit will require an independent reference probe in order to take advantage of the TQSoft automatic calibration feature.

CTC Complete Set

Interested in Purchasing a Temperature Calibrator?

See our full list of temperature calibrators on the Isopharm shop below, or contact us for more information

Do's & Don'ts of Using Temperature Calibrators and Reference Probes

• Thermal baths, particularly those incorporating a peltier device, can be damaged by turning them off while they are under strain. Allowing the bath to cool to around 50 degrees (or warm to around 0) before powering down will increase the lifespan of the device significantly.
• Reference probes can be very power hungry. If running on battery, make sure it is powered off, or you will probably need a new battery in the morning.