Investigations into protection from explosion when using cooling lubricants in machine tools

Status:

completed 09/1997

Aims:

Accidents caused by detonation of cooling lubricant fumes/vapours. Goal: determining the flammability and explosive pressure of atomised straight cooling lubricants under practical working conditions

Activities/Methods:

Determining explosion parameters in test vessels, ignition of free cooling lubricant vapour jets through mechanical sparking, electrical heating elements, hot surfaces; ignition of vapour sprays during grinding and drilling work at a lathe

Results:

The maximum explosion pressure in closed vessels amounted to 3.5 to 4.5 bar; all cooling lubricants with a flashpoint over 200 °C can be ignited by electrical sparks under 10 J and by hot surfaces (over 800 °C, during drilling and grinding); mechanical sparks (steel) do not cause the vapour to ignite.

Publications:

Hirsch, W.; Hempel, D.; Förster, H.: Untersuchungen zum Explosionsschutz beim Einsatz von Kühlschmierstoffen in Werkzeugmaschinen. PTB-Bericht ThEx-2. Physikalisch-Technische Bundesanstalt, Braunschweig 1997

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