| Abstrakt: |
The air-flow technique for the measurement of wool-fibre fineness has advantages over other methods because of its speed and convenience of testing. However, if the wool being tested is in the form of washed corings from greasy bales or corings from scoured bales rather than tops, the sample may contain impurities such as vegetable matter or sand and dust, and, although it is possible for such impurities to be removed, the treatment requires time and the continuous attention and judgement of a trained operator. The effect of the presence of impurities on the indicated mean diameter of wool fibres is therefore a matter of some importance, and an account is given in this paper of an investigation undertaken to study this effect. The theoretical basis of the influence of impurities on the indicated diameter is given, and it is shown that the experimental results are, in general, in agreement with the predicted values. Provided that the amount of vegetable matter present does not exceed 5% and coarse, sandy dirt is present to an amount not exceeding 1%, it is likely that the error in the indicated diameter resulting from the combined effects will fall in the range from 0 to +4.2%, i.e., the error would not exceed ±2.1% at the 95% probability level, which might be an acceptable figure for many purposes if an adjusted calibration were made. [ABSTRACT FROM AUTHOR] |
