Temperature data logger
A temperature data logger consists of at least a temperature sensor, an electronic memory, a microcontroller and a battery to operate the unit. It can have an external temperature sensor or an internal sensor. This is the case of the Thermo Bouton, a temperature data logger which concentrates all these elements in its stainless steel shell.
A temperature recorder thus makes it possible to measure the temperature at regular intervals and to store these temperatures in its memory. A complete history is thus obtained, allowing the temperature to be monitored over a precise period. In particular, a temperature recorder is used to monitor compliance with the cold chain in the pharmaceutical industry, biology laboratories and the food industry.
Indeed, cold chain regulations oblige these sectors to monitor the temperature during transport, storage and conservation of products. There are also temperature and humidity data loggers that allow both parameters to be measured at the same time.
Cold chain
The cold chain includes all the operations necessary to keep products (often food or pharmaceutical) at a low temperature to ensure the preservation of their qualities. Depending on the product, there will be different standards : +2 to +8°C for vaccines or many pharmaceutical or food products, or even with much lower tolerances such as fish.
The use of the word chain highlights the importance of the continuity of the steps. All the actors in the chain must ensure that this chain is maintained. The respect of the cold chain requires the use of control means such as temperature data loggers.
HACCP (Hazard Analysis Critical Control Point)
Hazard Analysis and Critical Control Points: according to the definition of NF V 01-002, HACCP is a system that identifies, evaluates and controls significant food safety hazards.
HACCP is not a standard, but a working tool. It is based on 7 principles. The implementation of HACCP is done through a succession of 12 steps, including the analysis of hazards and the identification of critical control points to control them.
The 3 families of critical points are as follows :
- Biological hazards (bacteria, viruses…).
- Chemical hazards (chemical residues, additives…).
- Physical hazards (foreign bodies, packaging…).
- In most cases temperature monitoring is one of the important critical points and the quality manager will have to monitor the respect of the cold chain. For this, he uses thermometers or temperature recorders such as Thermo Boutons.
See the article on HACCP on Wikipedia.
EN 12830 standard
Standard EN 12830 describes the metrological, electrical and mechanical properties that a temperature data logger must have for the transport, storage and distribution of refrigerated, frozen and deep-frozen foodstuffs and ice cream.
EN 12830 specifies, among other things, that the data logger must have an accuracy of ±1°C between -30°C and +30°C and a response time of 5 minutes.
Written for the agri-food sector, it was later applied to all sectors, particularly the health pharmacy sector.
Thermo Boutons temperature data loggers have all been tested and comply with the EN 12830 standard.
NF X 15-140 and EN60068-5 standard
The NF X-15-140 standard applies to the characterization and verification of climatic and thermostatic chambers, also called on site thermal mapping. It is progressively replaced by the European standard EN60068-5. This standard allows to check if an enclosure (refrigerator, oven, warehouse…) allows to keep a stable and homogeneous temperature.
The general principle is to validate that the set temperature is respected and does not deviate from the MPEs (Maximum Tolerated Deviations). Thus a bacteriology oven must be maintained at 37°C (setpoint) and remain between +36°C and +38°C (MPE of 1°C).
The mapping of an enclosure of less than 2m3 is done by placing 9 temperature data loggers distributed in the corners and in its center. For enclosures from 2 to 15m3, 15 temperature data loggers will be used. Beyond 15m3, the standard does not fix the number of temperature data loggers to be used.
Calibration
Calibration is the act of adjusting a device in relation to reference data in order to obtain a reliable behaviour during monitoring or reproduction. In the case of a temperature data logger, calibration is used to correct the deviation from a standard, which is measured during calibration.
According to the International Vocabulary of Metrology, calibration is the operation which, under specified conditions, establishes in a first step a relationship between the values and associated measurement uncertainties provided by standards and the corresponding indications with the associated uncertainties, and then in a second step uses this information to establish a relationship to obtain a measurement result from an indication.
The calibration of a temperature data logger is done by comparison with a precision thermometer or other data logger. It is understood that the standard must be more accurate than the instrument to be calibrated.
In a metrology laboratory, calibration is carried out in a bath that guarantees homogeneity and temperature stability. If a calibration bath is not available, the temperature data logger can be placed in a container of sand or a bowl of crushed ice. The use of crushed ice for the calibration of a thermometer or temperature recorder is a solution used to validate the temperature at 0°C when no standard is available.
A calibration must be accompanied by an uncertainty calculation that validates the method used and the result obtained.
On site thermal mapping
An enclosure thermal mapping module allows you to check whether the temperatures and hygrometry of your equipment are stable and homogeneous in accordance with NFX15-140, FD X15140 and EN 600683-5 standards.