Ashu Engineering Vacuum boxes provide high-efficiency cleaning of the synthetic wire and press felts of the paper machine. Ashu Engg. vacuum boxes carry away debris and water which is loosened by wire and felt cleaning showers. KanEng vacuum boxes should be located on the sheet side of felts, usually in a horizontal felt run, due to space limitation. Designs are also available for vertical felt runs.

Felt conditioning is located between the last pressure roll and the first paper side felt roll in the return run.

This positioning is chosen so as to avoid driving fibers and contaminants into the felt before surface cleaning.

The conditioning system consists of two showers and two Uhle boxes. A high volume flooding nip showers is located at the first felt roll after the press and is followed oscillating needle shower. The first Uhle box is positioned in the vertical run after the flooded nip shower and the second Uhle box before the stretch assembly.

Suction box tops should be made from plastic or preferably ceramic material. The slot width on the suction box should be designed so as to give the correct dwell time (see separate fact sheet).

Showers should be easily accessible to allow easy cleaning and maintenance.

The oscillation speed of the high pressure shower should be such that the shower bar moves a distance equal to 1 nozzle orifice diameter for every revolution of the felt.

Chemical cleaning should be carried out using a fan type shower to give 100% coverage of the felts surface and far enough away from the conditioning box to allow penetration of the felt by the chemical. If the felts are chemically cleaned on crawl then the conditioning box can be temporarily turned off to allow the felt to "soak”.