The first series was established in 1972. It was the result of the most extensive testing and retesting that significant quantities of standard wool tops have been established. Limited to a maximum duration of 3 years, this series has replaced by seventeen further series, each of them having been valid for a period progressively reduced to 2 years. The 23rd Series will be valid until 31 January 2022, with respective finenesses as follows:
24th SERIES OF IH-STANDARDS (Valid : 01.02.2022 - 31.01.2024)
Standard Values to be used for the calibration of the Instruments for the fibre diameter measurements
STANDARD VALUES
| Standard No. | Mean fibre diameter (µm) | Mean fibre diameter (µm) | Distribution of fibre diameter (CV %) | Fibre Curvature (deg/mm) |
|---|---|---|---|---|
| 1 PM | not applicable | 15.53 | 18.64 | 80 |
| 1 AF | 17.64 | not applicable | not applicable | not applicable |
| 2 | 18.86 | 18.73 | 18.89 | 69 |
| 3 | 20.74 | 20.66 | 20.29 | 66 |
| 4 | 23.48 | 23.51 | 19.75 | 59 |
| 5 | 27.87 | 27.98 | 22.00 | 59 |
| 6 | 30.63 | 30.61 | 22.86 | 53 |
| 7 | 32.85 | 33.34 | 25.87 | 56 |
| 8 | 36.80 | 36.83 | 21.72 | 39 |
Eight Tops are required to calibrate Airflow (IWTO-6), Laserscan (IWTO-12) and OFDA (IWTO-47).
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To calibrate Airflow Instruments, tops “1AF” and “2” to “8” only shall be used.
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To calibrate Laserscan and OFDA instruments, tops “1PM” and “2” to “8” shall be used. Do not use top “1AF”.
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