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Bauer McNett Fibre Classifier

Bauer McNett Fibre Classifier

For the determination of fibre length of pulp by classification

  • Features

    • Mounting frame and classification units made entirely of stainless steel
    • Quick-locks for screens and drainage cups
    • Vacuum-pump to speed up the draining at the end of the test
    • Standard screens: ASTM 16 / 30 / 50 / 100 / 200
    • Ideal for upstream mounting of shive content analyser like Somerville Screen, Haindl Classifier, or Brecht-Holl Classifier
    • Fully automatic testing


    The Bauer McNett fibre classifier consists of up to 5 narrow tanks 255 mm deep, 127mm wide and 320 mm high, mounted in a cascade arrangement, with screens of 335 cm² mounted on the flat side. A vertical, cylindrical agitator with short paddles rotates at 580 rpm near one semi-circular end of each tank. This causes the suspension in each tank to flow horizontally across the screen and circulate around the tank. An overflow weir is provided at the outgoing side of each screen, and a short pipe leads to the next tank with a finer screen, at a slightly lower level, or from the last tank, to drain away. A flow regulator supplies water at the rate of 11.35 l/min to the first tank. The motion of the water keeps the fibers from settling and presents them repeatedly to the screen through which they will pass if their length is less than twice the screen opening.

    Test description

    With the screens correctly mounted in the tanks press the start button to start the water flow into the top tank. As soon as the lowest tank starts overflowing, press the start button again and simultaneously start to pour the prepared sample of 3,333 ml (with 24 g of moisture-free pulp) during a period of 18 seconds into the top tank. Subsequently the flow at the rate of 11,355 l/min into the top tank, the stirrers and the timing of 20 min are started automatically. A green lamp shows that the classification is in progress. During this time the drainage cups are furnished with weighed and marked filter papers. After the test (20 minutes according to TAPPI, 15 minutes according to SCAN) the water influx is stopped automatically and the green lamp goes out. The stirrers continue running for another 2 minutes until there is no more water flowing to drain away from the lowest unit. Now the drain plug and tap below the cup of the first tank is opened and the pump is turned on to allow the contents to drain into the cup. After the tank has been drained, the screen and tank is flushed carefully with the provided hose. When all the tanks are emptied in this way the pads are taken out of the cups and folded in the middle. As much water as possible is removed using a wringer, a blotter or towel. Before weighing to within 0.01 g the pads are dried in an oven at 105°C to constant weight.


    • 3, 4 or 5 tank units
    • Unit mounted on stainless steel frame
    • Stainless steel tub with drain
    • Stainless steel control cabinet included
    • Ready for use delivery (plug & operate)
    • On the left side of the unit is sufficient space to mount a shive content analyser (Brecht-Holl, Haindl or Somerville Screen)
    • Vacuum pump for fast draining
    • Spraying nozzle and hose for cleaning included
    • Quick release fasteners for screens and cups
    • Fully automatic process
    • Tub and rack for storage of unused screens

    Technical data

    Electricity: 230 V, 50/60 Hz
    Water supply: 2 bar min (drinking water), Drain: ¾” hose
    Compressed air: None
    Dimensions (WxDxH): 170x60x150 cm
    Net weight: 170–230 kg
    Gross weight: 220–300 kg

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