Temperature data logger: thermometer, stand-alone logger or connected sensor?
A temperature data logger is an instrument that measures the temperature at regular intervals and stores each reading with its time, to prove after the fact that a fridge, a cold room or a vehicle stayed within the prescribed range. It differs from the thermometer, which only shows the moment, and from the connected sensor, which records and alerts as well. For quick-frozen food in transport and storage, Regulation (EC) No 37/2005 requires a recorder complying with EN 12830, EN 13485 and EN 13486 and records kept for at least one year; for everything else, the HACCP plan sets the instrument.
A sensor that records, alerts, and has nothing to get signed.
KelvinTag records continuously, timestamps at source, alerts the moment the range is left and exports the history as a PDF. It is bought once, with no subscription: an Android phone serves as the free gateway.
Three families of instrument, three levels of proof
The question is not the brand but the family: what the instrument keeps, what it proves in front of an inspector, and what it does when the temperature drifts at three in the morning. The differences are of kind, not of degree.
| Criterion | Thermometer | Stand-alone data logger | Connected sensor |
|---|---|---|---|
| What it does | Shows the temperature right now; some keep the minimum and maximum since the last reset. | Measures at a fixed interval and stores each value with its time; the history is retrieved by cable or reader. | Measures, stores and transmits; the history can be viewed remotely and exported. |
| Proof for an inspection | The manual reading somebody wrote down, at the time they wrote it. | The timestamped curve, provided it was downloaded and archived. | The timestamped curve, already on the server, exportable at the moment of the inspection. |
| Alert on a drift | None, except a local audible alarm on some models, heard if someone is there. | The drift is discovered at read-back, after the fact. | Immediate, as soon as the limit is crossed, as long as the link is up. |
| What is still done by hand | Everything: read, write, date, sign, at every reading. | Retrieve the data, read it, archive it; watch between two read-backs. | The core temperature of the food, during cooking and cooling, which remains a probe measurement. |
| Cost over time | The device, then someone's time at every reading, every day. | The device, sometimes software, and the time spent on read-backs. | The device, and depending on the vendor a subscription per sensor, per site or per user: the line to read before the purchase price. |
What the regulation requires, and where
Quick-frozen food, in transport and storage: Regulation (EC) No 37/2005 requires suitable recording instruments that monitor the air temperature at frequent and regular intervals, complying with EN 12830, EN 13485 and EN 13486; the records are dated and kept by the operator for at least one year, or longer depending on the nature and shelf life of the products. Article 3 carries the derogations: in retail display cabinets and during local distribution, an easily visible thermometer is enough, and the competent authority may allow the same for cold stores under 10 m³ holding a shop's stock.
Chilled food, in kitchens, shops and warehouses: Regulation (EC) No 852/2004 prescribes no type of instrument. It requires effective monitoring procedures at the critical control points and documents and records commensurate with the business, retained for an appropriate period; its Annex II says the cold chain is not to be interrupted. The choice between thermometer and logger is therefore the one your food safety plan makes, and that is where an inspection will read it.
Medicines and healthcare products: the Good Distribution Practice guidelines require a mapping of storage areas before use, monitoring devices positioned according to its results, and monitoring equipment calibrated at defined intervals. The instrument there is therefore a recorder, placed at the worst-case point, with a documented calibration.
The seven questions to put to any vendor
- 1
Accuracy and range, at the temperature of use
The stated accuracy holds over a given range; ask for it at the temperature of your coldest enclosure, freezer included, not only at room temperature. The measuring range must cover that enclosure with margin.
- 2
Calibration and traceability
A monitoring instrument is worth what its measurement is worth. Ask whether the sensor is calibrated on delivery, whether a certificate traceable to national standards is supplied or available, and how periodic verification is done. For medicines, the Good Distribution Practice guidelines require monitoring equipment calibrated at defined intervals.
- 3
Measurement interval and memory
How often the instrument measures, how long its memory lasts, and what it does when the memory is full or the link is down: does it overwrite the oldest readings, lose them, upload them when the connection returns? The answer decides whether a network outage is a hole in your records.
- 4
Alert: who receives it, and without internet?
An alert is only worth something if it reaches someone who can act, nights and weekends included. Ask which channel it goes out on, what happens if the gateway loses internet, and whether the device signals the drift on the spot in the meantime.
- 5
Air or product, and where in the enclosure
Most loggers measure the air of the enclosure, which moves faster than the food; some accept a probe placed in a simulated product. In both cases the location matters more than the model: the useful measurement is at the worst-case point, the one a temperature mapping finds.
- 6
Export and retention of the records
An inspector reads a dated history, not an app. Ask what format the history exports in, whether it is readable without the vendor's software, and how long it stays available; for quick-frozen food the regulation asks for at least one year.
- 7
Total cost, subscription and battery included
The purchase price is the visible part. Add the subscription if there is one, per sensor, per site or per user; the gateway, if it is charged; and the end of life: replaceable battery or sensor to replace, and what the warranty covers.
Where KelvinTag sits
The same seven questions, with our answers as they stand on the product page, last line included.
- Family
- Bluetooth connected sensor with its own memory: three years of readings on board, uploaded when the connection returns.
- Accuracy and range
- Up to ±0.05 °C, from -40 °C to +85 °C, IP68 rated. Calibrated before shipping, NIST traceability; documented calibration optional, annual service available.
- Alert
- The sensor blinks red on the spot as soon as its reading leaves the range; the alert goes out through the gateway as long as it has internet, and missing readings upload afterwards.
- Gateway
- An Android phone with the free app, at least seven sensors per phone; the Poliponet 5G gateway, with its own SIM, optional and charged monthly.
- Proof
- History timestamped at source, PDF export, kept three years on our servers as in the sensor.
- Cost over time
- The sensor is bought once, with no subscription, per sensor, per site or per user. Battery guaranteed three years, not replaceable; three-year warranty on the sensor, physical damage excluded.
- What it does not do
- It measures the air of the enclosure, not the core temperature of the food. And this page claims no certification to the standards named above for it: for a use covered by the quick-frozen regulation, ask before ordering, us as any other vendor.
Sources
- Commission Regulation (EC) No 37/2005 of 12 January 2005 on the monitoring of temperatures in the means of transport, warehousing and storage of quick-frozen foodstuffs - the recorder requirement (Article 2), EN 12830, EN 13485 and EN 13486, records kept at least one year, and the thermometer derogations (Article 3). Retained in UK law.
- Regulation (EC) No 852/2004, Article 5 and Annex II, Chapter IX - monitoring and records at the critical control points, the cold chain not to be interrupted, and records retained for an appropriate period.
- EN 12830, EN 13485 and EN 13486 - recorders, thermometers and periodic verification; European standards from CEN, available from the national standards body.
- Guidelines on Good Distribution Practice of medicinal products for human use (2013/C 343/01), section 3.3.2 - for healthcare products: monitoring equipment calibrated at defined intervals, based on a risk and reliability assessment.
Frequently asked questions
For chilled food, no text prescribes a type of instrument: Regulation (EC) No 852/2004 requires monitoring at the critical control points and records commensurate with the business, and the food safety plan says what the monitoring is done with. For quick-frozen food in transport and storage, yes: Regulation (EC) No 37/2005 requires a recorder complying with EN 12830, EN 13485 and EN 13486, with a derogation for retail display cabinets, local distribution and, with the authority's agreement, cold stores under 10 m³ in retail outlets, where an easily visible thermometer is enough.
A thermometer shows the temperature right now, sometimes the minimum and maximum since it was last reset; it keeps nothing, and the proof remains whatever somebody wrote down. A data logger measures at a regular interval and stores each reading with its time: the curve can be read back later and exported. A connected sensor is a data logger that also transmits its readings and raises an alert when a limit is crossed, instead of waiting for the read-back.
They are the three standards Regulation (EC) No 37/2005 requires of the instruments used for quick-frozen food. EN 12830 covers temperature recorders for transport, storage and distribution; EN 13485 thermometers for measuring air and product temperature; EN 13486 the periodic verification of those recorders and thermometers. A manufacturer claiming them must be able to hand over the attestation of conformity; ask for it before buying for a use the regulation covers.
For quick-frozen food, Regulation (EC) No 37/2005 is explicit: the records are dated and kept by the operator for at least one year, or longer depending on the nature and shelf life of the products. For other food, Regulation (EC) No 852/2004 asks for documents and records to be retained for an appropriate period, without fixing one; the food safety plan sets it. An instrument that exports the dated history as a readable file makes that retention trivial.
For the temperature of the enclosure, yes: the timestamped history is the record the HACCP plan asks for, and it is produced without anyone remembering to take a reading. It does not measure the core temperature of the food, during cooking or cooling, which remains a manual probe measurement. Many businesses keep the paper sheet for those measurements and as a fallback.
The logger that warns before the inspection finds out
One sensor per enclosure, an Android phone as the gateway, no subscription. The timestamped history exports as a PDF the day someone asks for it.
See the KelvinTag sensorSee also
The other documents in the food-safety file, free to download or generate.
- Temperature log sheetGenerate a blank sheet matched to your cold enclosures and their limits, ready to post in the kitchen.Open
- Food safety plan templateThe full structure of a food safety management system - hygiene practices, HACCP plan, traceability - with your enclosures pre-filled and the questions each section must answer.Open
- Food traceability registerGoods received or opened products: a blank book ready to fill in, with the columns an inspection expects (lot, use-by, temperature on arrival).Open
- Allergen matrixDishes × 14 allergens to tick, or the Annex II list to display: the written document the rules expect front of house.Open
- Cleaning and disinfection planThe area-by-area plan to fill in, plus the daily record that proves it is applied.Open
- Storage temperaturesRegulatory storage temperatures by food category: chilled, frozen, hot holding and healthcare products.Open
- Use by and best before datesWhat each date means, what may still be sold or served once it has passed, and the article of Regulation 1169/2011 that says so.Open
- The HACCP methodDefinition, the seven principles of Article 5 of Regulation 852/2004, the twelve steps, foodborne outbreaks and what training actually requires.Open
- Food hygiene inspectionWho inspects, which records you are asked for, and what can follow a visit - from a reminder of the rules to an order to close all or part of the premises.Open
- Temperature mappingWhen it is required (Good Distribution Practice for medicines), the method in six steps, and where the monitoring probe goes afterwards.Open
- Cold-chain breakFridge failure, door left open, vaccine out of the fridge: what the texts say, what decides the fate of the goods, the five moves of the first hour and the signals before a breakdown.Open
- Use-by date tracking sheetWhat is in stock and its date, for the daily check: product, lot, use-by or best-before, location, exit.Open