Humboldt H-1474 Centrifugal Extractor - Manual (Page 3)

8. Replace the housing cover and secure the clamps.
9. Place a collection beaker under the discharge pipe (#11) at the left of the
bowl housing.
10. Pour no more than 450 cubic centimeters of trichloroethylene solvent into the
filter cup of the upper housing cover (#10).
Caution: Provide adequate ventilation when using solvents.
Do not exceed 450 cu. cm of trichloroethylene or flooding will occur causing
damage to the motor and/or bearing and transformer. If sample has been
preheated allow 2 or 3 minutes to digest. If not pre-heated allow 10 to 15 minutes
to digest.
11. Start rotation slowly by turning knob on the speed control box in a clockwise
direction. Increase speed gradually until fine stream of liquid is emitted from the
discharge pipe. Maintain this speed until the discharge stops, and then gradually
increase the speed until no further discharge is obtained.
Caution: A too-rapid rate of acceleration during this step may cause flooding
which in turn can result in an inaccurate test and possible damage to the machine.
Flooding maybe observed by a rapid and excessive discharged followed by
seepage of liquid at the housing cover or the underside of the housing. Correct
this condition by immediately reducing the speed.
12. Return the speed control knob to the zero position in order to apply the brake.
13. Pour in another 450 cu. cm. of solvent and repeat steps 3.11 and 3.12 in the same
sequence. Continue this process until the discharging liquid appears pale amber
in color. The extraction process is then complete.
14. Remove the housing cover and lift out the bowl. After removing the nut and
bowl lid, wash with solvent the under surface of the lid into the beaker.
15. Carefully lift the filter disc from the bowl lip and brush any clinging particles
into the bowl. The filter maybe burned over the sample for complete recovery of
fines making allowances for ash correction.
Precautions
A. Loss of Fines:
4.1 Avoid excessive speed and acceleration especially at the beginning of a test cycle
when a lot of solvent is present.
4.2 Do not over-tighten the bowl nut.
4.3 Use a heavier filter disc or two standard discs.
4.4 Burn the filter over the sample. Make ash correction.
4.5 When test is complete, carefully brush all dust from the bowl lip and underside of
the bowl cover into the sample.
B. Warp age of Bowl and Lid
Make the following check for possible warp age of bowl and lid.
4.6 Put the lid in place (no filter) and hand tighten the bowl nut.
4.7 Try to insert a 0.005” feeler gauge or shim at any point.
4.8 If the gauge passes through, the bowl or cover should be re-faced or replaced.