This article explains what Temperature Sensor calibration is, why it matters, and how it’s done for Disruptive Technologies (DT) sensors. It provides an overview of DT’s calibration options for temperature sensors, including accuracy and long-term drift. Finally, it discusses how to validate that the sensors continue to measure accurately over time (recalibration and temperature validation).
What is Temperature Sensor calibration?
Temperature calibration is the process of comparing and adjusting a sensor’s readings against a known reference to ensure accurate measurements. Regular calibration (or recalibration) helps maintain reliable measurements over time, ensuring that sensors perform within the specified accuracy for their respective use cases.
DT temperature sensors and calibration
The temperature sensors from Disruptive Technologies offer excellent accuracy, long-term stability, and continuous reporting, with no need for recalibration in most use cases.
Every sensor has a factory-calibrated sensing element, making it suitable for most use cases right out of the box. For applications with stricter accuracy or certification requirements, DT also offers standard calibration and accredited calibration services.
Calibration options are offered for the following products:
- Temperature Sensor
- Temperature sensor with Data Backfill and Mounting Bracket
- Temperature Probe Sensor
- Temperature & Humidity Sensor (US variant only)
Accuracy definitions
Accuracy - shows how near a measurement is to the actual temperature. Calibration improves accuracy by correcting consistent errors, but since measurements can vary with temperature, a single calibration point won’t ensure accuracy at all temperatures.
Typical accuracy - Real-world accuracy during regular operation, including effects from wiring, instruments, and ambient conditions.
Max accuracy - Worst-case total accuracy over the full operating range, accounting for all possible error sources. Important to note: In practice, errors may be larger in extreme scenarios.
Uncertainty - shows how confident we are in the true temperature during calibration. Unstable conditions, such as temperature changes or electrical noise, can increase uncertainty. Calibrating in a stable lab environment helps reduce it.
Built-in Calibration
All DT Temperature sensors have factory-calibrated sensing elements to ensure baseline accuracy. This initial calibration serves as the reference point for all subsequent verification or certification steps.
The manufacturer performs calibration according to the table below.
| Sensor Type | °C | °F | ||||
|---|---|---|---|---|---|---|
|
Typical Accuracy |
Max Accuracy |
Max Yearly Drift |
Typical Accuracy |
Max Accuracy |
Max Yearly Drift | |
|
Temperature Sensor Temperature Sensor w/Data Backfill and Mounting Bracket Single-point calibration 25°C (77°F) |
>60 ⇒ ±0.3 5-60 ⇒ ±0.2 -25-5 ⇒ ±0.3 <-25 ⇒ ±0.6 |
5–60 ⇒ ±0.7 15–45 ⇒ ±0.4 |
0.04 |
>140 ⇒ ±0.54 41–140 ⇒ ±0.36 −13–41 ⇒ ±0.54 <−13 ⇒ ±1.08 |
41–140 ⇒ ±1.26 59–113 ⇒ ±0.72 |
0.072 |
|
Temperature & Humidity Sensor¹ 3-point calibration (–30°C, 5°C, 70°C | −22°F, 41°F, 158°F) |
>60 ⇒ ±0.2 5–60 ⇒ ±0.1 <5 ⇒ ±0.2 |
−40–85 ⇒ ±0.3 |
0.03 |
|
−40–185 ⇒ ±0.54 |
0.054 |
|
Temperature Probe Sensor² Resistance calibration (100Ω/400Ω) |
±(0.15 + 0.2%) |
65 ⇒ ±1.45 -200 ⇒ ±0.55 |
0.05 |
149 ⇒ ±2.61 −328 ⇒ ±0.99 |
0.09 | |
¹ The manufacturer uses ISO 17025–traceable reference standards.
² Probe accuracy varies with temperature and meets Class A standards. Typical and base accuracy only for DT-provided probes.
Calibration Options
DT Standard Calibration
For applications that require higher precision, DT offers an optional Standard 5-point calibration for:
| Sensor Type | Calibration Method | Max Accuracy | Long-term Stability | Notes |
|---|---|---|---|---|
|
Temperature Sensor Temperature Sensor with Data Backfill and Mounting Bracket |
5-point calibration at −20 °C (−4 °F), 0 °C (32 °F), 10 °C (50 °F), 20 °C (68 °F), 50 °C (122 °F) |
±0.25 °C (±0.45 °F) across calibrated range |
Max 0.04 °C drift per year (0.072 °F/year) (≈ ±0.5 °C / ±0.9 °F after 6 years) |
Performed with ISO 17025-traceable equipment (service not accredited but follows accredited lab method. DT Calibration Certificate included; corrected data automatically applied in DT Studio and via API. |
Accredited Calibration
For customers who need ISO 17025-accredited calibration certificates, DT partners with accredited labs in Europe and the United States. This service provides fully accredited calibration and traceable results for sensors and probes.
| Sensor Type | Calibration Method | Max Accuracy | Long-term Stability | Notes |
|---|---|---|---|---|
Temperature Sensor |
3-point calibration (typically –20 °C / −4 °F, 0 °C / 32 °F, 10 °C / 50 °F) |
±0.25 °C (±0.45 °F) lab uncertainty dependent |
Max 0.04°C drift per year (0.072 °F/year) |
Accredited ISO 17025 certificate included. Custom calibration points are not currently supported. |
Temperature & Humidity (T&H) Sensors |
3-point calibration (Temperature calibration 0°C, 15°C, 30°C and Humidity calibration at 50% (at 20-25°C) |
±0.25 °C (±0.45 °F) |
Max 0.03°C drift per year |
Currently only available in the US. |
Temperature Probes |
Calibrated as a paired probe + sensor unit |
±0.25 °C (±0.45 °F) |
Max 0.05°C per year* *Concerns DT Probes only |
Only available via the factory and an accredited lab. The probe and sensor must be used together. |
Recalibration Frequency
Due to the sensor’s excellent long-term stability, recalibration is often not required. However, industries with strict quality assurance may still require regular validation checks. These checks go beyond sensor accuracy and can include verifying proper placement, inspecting for mechanical damage, and ensuring sensors are functioning correctly.
How often the sensors need to be calibrated or checked depends on the drift rate, accuracy requirements, and other factors.
If a sensor shows an unexpected offset, stops reporting, or is difficult to recalibrate, replacement can be more straightforward and more cost-effective than recalibration.
To determine an appropriate recalibration interval, it is important to consider the accuracy requirements over time, as discussed in the examples below.
Example 1: Grocery Store Fridge
A sensor installed in a fridge refrigerator maintains a temperature of 3°C. The sensor is a Temperature Sensor with the Standard Calibration option for increased accuracy. For this example, we assume the grocery store requires a 0.5°C accuracy for the temperature log, meaning a reported value between 2.5°C and 3.5°C would meet the requirements.
You can find the actual initial accuracy in the calibration certificate (accuracy = correction + uncertainty), or use 0.25°C as a conservative estimate.
If we look at the accuracy over time for the standard calibrated temperature sensor, we get a development like this: ±(0.25°C + 0.04°C/Year).
We can see that the sensor would meet the accuracy requirement for 6 years. Thus, the maximum recommended calibration interval is also 6 years.
Other considerations, such as compliance, sensor position, changes in the refrigerator, etc., may warrant a shorter recalibration interval. The in-field temperature validation procedure can be used to verify the accuracy along the way and to comply with time-based checking requirements.
Example 2: Hospital Lab Ultra Freezer
For the second example, we will consider a temperature probe sensor with accredited calibration in an ultra-cold freezer. The freezer is expected to maintain -80°C. The accuracy requirement will vary a lot depending on what the freezer is storing, but 0.5 °C is a typical requirement, with recommended yearly recalibration.
From the calibration certificate, we see that the temperature probe has a correction of 0.00°C and an uncertainty of 0.03°C at -80°C, giving an initial total accuracy of 0.03°C. The maximum drift for the probe sensor, using DT-provided probes, is 0.05°C/year.
In this scenario, the recommended calibration is much more frequent than the minimum required to meet the accuracy requirement. We can therefore instead compare the accuracy of an annually-calibrated system to a system only calibrated once:
The yearly calibration interval ensures an excellent 0.08 °C accuracy for the entire system. Even though the single calibration will remain within the required limits for a long time, the items stored in the ultra-cold freezer often carry an increased risk, warranting the very tight accuracy range provided by a yearly calibration.
Recalibration and Temperature Validation
If you decide recalibration or recheck of the accuracy is required, you can either recalibrate or revalidate to ensure the sensors are performing to your needs. Recalibration improves the accuracy of temperature measurements, while temperature validation assesses the sensor's current accuracy.
Recalibration of Temperature Measurements
DT does not offer recalibration services after shipment, but you can recalibrate the sensors yourself or have a professional service do it. After calibration, you can set the offset in your own software to adjust each sensor's readings.
For the Temperature Probe, you can enter new Probe Coefficients after calibration in Studio.
Temperature Validation
For the Temperature Sensor installed in the Mounting Bracket Temperature, we provide straightforward revalidation support through Studio and the API. The process is to place a newly calibrated Temperature Sensor on top of an installed sensor for a few hours and then compare the readings. Once completed, we provide an overview of the offset and whether the sensor is still within the expected accuracy.