Pt100 - Temperatur Sensors

-Explosion protection for Pt100 resistance thermometers-

About the site

This is a private information page about electrical temperature measurement with resistance thermometers (e.g. Pt100, Pt500, Pt1000). My experiences of many years in the field of measurement and control technology are recorded. I do not take over any liability for incorrect information and would be pleased about further suggestions and requests for additions.
Please also visit my information page about variable area flowmeters: https://schwebekörper.de/en

Suppliers of Pt100

Links to selected manufacturers and suppliers of Temperature Sensors.

Tools

ATEX

Every operator who wants to measure the temperature of explosive substances with Pt100 resistance thermometers, has already dealt with the subject of “explosion protection” and has come across the term ATEX.
ATEX is an abbreviation of the French term Atmosphères exlosibles (explosive atmospheres).
ATEX is mainly based on 2 directives that are legally binding in the European Union.

Explosion protection zones

Areas with potentially explosive atmospheres, also known as explosion protection zones, occur wherever flammable substances in the form of gases, vapors, mists or dusts can occur in hazardous concentrations. These play a central role when working with flammable substances.
In order to minimize risks for people, systems and the environment, explosion protection zones are divided into different categories, each of which requires different safety requirements. The classification is based on the probability and duration of the occurrence of a hazardous explosive atmosphere.
This systematic classification is the basis for the selection of suitable protective measures, such as explosion-proof devices and safety-conscious operating procedures, and ensures operational safety in potentially hazardous environments.

Image Ex Protection zones

Combustible gases
Combustible dusts
Definition of the zone
Zone 0
Zone 20
An explosive atmosphere is present continuously, frequently or over a long period of time.
The terms “frequently, constantly” are not defined in the DIN standard.
It is generally agreed that this is the case if an explosive atmosphere is present for more than 50% of the operating time of a system.
This applies, for example, inside pipes and containers.
Zone 1
Zone 21
An explosive atmosphere is occasionally present.
The term “occasionally” is not defined in the DIN standard.
It has generally been agreed that this is the case when an explosive atmosphere occurs at irregular intervals and does not exceed a period of 1 to 10% of the operating time of the system.
This is the case, for example, in the immediate vicinity of zone 0 if samples are taken occasionally or the system is vented.
Zone 2
Zone 22
Explosive atmospheres are only rare and short-lived.
The terms “rare, short-term” are not defined in the DIN.
It has generally been agreed that this is the case if an explosive atmosphere is present for less than 1 to 10 hours per year.
This is normally only the case due to faults and is not normally to be expected during normal operation.