a sealed shower system applies shower water to a pulp mat as it passes through a sealed chamber under a vacuum with an air supply that is externally regulated . the shower water forms a pond or film on the pulp mat . the amount of entrapped air is minimized through a downleg of a filter drum which results in maximum filtrate flow , an increased drainage rate , higher efficiency washing and a requirement for less shower water per pound of pulp . in addition , with less entrapped air in the filtrate , the length of the downleg can be reduced enabling lower building heights , smaller filtrate tanks and foam handling systems . the sealed shower system also forms part of a combined shower / hood structure that greatly reduces exhaust emissions .