by means of perforated plates defining expansion chambers associated with condensation and collection chambers

Full Title

Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust (electric control F01N9/00; monitoring or diagnostic devices for exhaust-gas treatment apparatus F01N11/00) > for cooling, or for removing solid constituents of, exhaust (by means of electric or electrostatic separators F01N3/01 ) > by means of perforated plates defining expansion chambers associated with condensation and collection chambers