Product catalogue 2009/2010 - ecom instruments - (Version JPG) - Page n° 9 - PDF Catalogue | Technical Documentation

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Division into Temperature Classes

The temperature class indication can be guaranteed only if the ambient temperature specified for the operating device is respected (see Technical Data or Rating Plate). Strict compliance is a mandatory requirement.

Once the maximum surface temperature of any apparatus reaches the ignition temperature of the surrounding hazardous atmosphere an explosion can occur:

Because of this, all equipment classified to Group II is divided into temperature classes. To allow for the possibility of potential hazardous atmospheres, the lowest ignition temperature must always be higher than the maximum surface temperature.


Temperature classes of flammable gases and vapours and permitted surface temperatures of the operating device in accordance with DIN EN 50014
Temperature class	Tl	T2	T3	T4	T5	T6
Ignition temperature in °C	>450	>300	>200	>l35	>l00	>85
Maximum Surface temperature in °C	450	300	200	135	100	85
Eg.	Propane Methane Ammonia	Ethylene Alcohols Acetylene	Petrol Solvents	Ethylether Acetaldehyde	-	Carbon-disulphide

Explosions are dependent on many parameters.

For only atmospherical conditions and pure substances sufficient comparitive values and data are shown. An explosion can only occur where a flammable substance in the form of gases, vapours, smoke and dust exists along with sufficient oxygen to support combustion and there is a source of ignition.

e.g.

- Hydrogen

- Ammonia

4,0 bis 77,0% in air 15,4 bis 33,6% in air

Propane

Methane

l,7 bis l0,6% in air 4,4 bis l6,5% in air

Product catalogue 2009/2010 - ecom instruments - #9

Explosion-proof lamp, Calibrator, Portable calibrator, Tachometer, Wall thickness gauge