Abstract
It is a well-known fact that the relative humidity of air may have an influence on the build-up of static electricity on equipment, installations, packages, personnel, etc.. However the questions arise whether in industrial practice the increase of the relative humidity of air is sufficiently effective to prevent ignition of explosive atmospheres by static electricity, whether at high relative humidity earthing is no longer required and what are the limit values. In the present paper comprehensive measurements and results are presented, which clearly show that even an increase of the relative humidity of air above approximately 70% does not reduce the build-up of static electricity to such a degree that the well-known measures like earthing, use of conductive or dissipative materials, etc. are no longer required.
