Electrostatic powder spraying equipment - has particles fed at high rate through annular charging channel for frictional charging

摘要

The particles suspended in air are fed to a charging channel (12) with a statically charged electrical isolator. The paricles are transported through the charging channel (12) at a rate of between 60 and 260 m/sec., so that they are charged by friction. Pref. the spraying equipment has a cylindrical plastics housing (1) with an internally threaded section into which a metal insert (2) is screwed. This has an interior metal insert (4) having a bore receiving a 'Teflon' (RTM) pipe (6). This has a tapering initial section (6a) coupled to the line (8) along which the powder particles are fed and a subsequent cylindrical section (6b) into which a pin (4c) integral with the interior metal insert (4) projects, to define the annular charging channel (12), the insert (4) coupled to a HV source.