Page 104 - QRedition5.0 062021

Quality Requirements Edition 5.0 European Enamel Association

steel keep their electrical charge for some time. The Coulomb interaction between the A – measuring cell of PTFE Measuring Principle
negatively charged particle (powder) layer and the positively charged steel plate will only B – electrode stamp
continue as a long as the charge difference remains. After the entire loading of the particles C – bottom plate
has flown off, the particles fall down. Consequently, enamel particles must have dielectric D – vertical adjustment
properties and have therefore a high current flow resistance. Untreated enamel powder E – steering rods

does not adhere because of the relatively high conductivity of the surface bound OH- F – clamp
groups and adsorbed water. By coating the powder with reactive Silanol components the G – ground
harmful influence of the OH-groups and traces of water can be eliminated and the surface H – diode socket
conductivity can be reduced considerably. As a result, coated powders show an increased I – printer connection
surface resistance of about 7 orders of magnitude! K – electrode connection
L – power supply
M – switch button
The surface resistance is a measure of the efficiency of the particle coating. Moreover, it
indicates whether the coated powder withstands any attack by humidity out of the air after N – voltage control
ageing. Powders with a high surface resistance (>10 Ω) result in good figures for the O – resistance range
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powder adhesion. P – resistance display

Standard Cell Commercial Measuring Unit

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EEA2020