felt 1 the flow of purging air as indicated by arrows for the example of vacuum in conduit 24 is conducted over the edge 31 through the base layer 2 into slots 30 through holes 29 groove 28 and passages 27 and into the chamber 33 in fig4 a felt 111 is guided in the direction of the arrows over felt rolls 115 to a felt purger 101 and over its supporting surface 109 an internal shower pipe 100 cleans or moistens the inside surface of the felt loop 111 and an external shower pipe 116 cleans and moistens the outside surface of the felt loop 111 a scraping blade 118 is fastened to cross machine beam 117 and removes surface contaminations from the felt 111 the felt purger 101 is composed of a suction box 107 extending over the width of the machine to which a nozzle block 105 is fastened by clamping bars 106 for purging water out of the carrier layer 113 of felt 111 the suction box 107 is connected to a vacuum source blower or pump via vacuum line 119 air is drawn from the longitudinal air supply slots 110 through the carrier layer 113 of felt 111 into suction slots 104 through passages 108 and 103 and into suction box 107 the felt purger 101 is more closely described in fig5 and 7 using the same reference numbers of identification fig5 is only an enlarged cross sectional view of the air purger 101 of fig4 it is visible that the bores 108 extending from bores 103 terminate at a depth at which they intersect with suction slots 104 but do not meet the air supply slots 110 this relation is even more clearly visible in fig6 each.