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ISO 4044-2017 pdf free download
ISO 4044-2017 pdf free download.Leather Chemical tests Preparation of chemical test samples
Cuir — Essais chimiques – Preparation des échantillons pour essais chimiques.
6 Preparation of test sample
6.1 Sample preparation
Test pieces that are wet (i.e. in excess of approximately 30 % moisture) should be pre-dried at a temperature not exceeding 40°C. The drying temperature should be selected with consideration of the influence of elevated temperature on the nature of the analyte.
If the samples are dried at elevated temperature, they shall be conditioned according to Iso 2419.
This method of preparation shall be used when a sufficiently large piece of leather is available for grinding in a mill (5.1) to give a representative ground leather sample. As a guideline for the purpose of this document, the leather sample should be at least 200 mm x mm or more than 10 g.
Before grinding, the samples of leather should be reduced to small pieces of suitable dimensions depending on the design of the cutter mill feed system.
It shall be ensured that the grinding mill and sample collecting device are clean. Water should not be used for cleaning.
If sufficient sample is available, then a few small pieces of test leather should be ground and discarded, with the apparatus being cleaned again before proceeding with grinding the main test sample.
Examples of a suitable apparatus available commercially are given below, This information is given for the convenience of users of this document and does not constitute an endorsement by ISO of these products.
A.2 Grinding apparatus
A suitable grinding mill (also called cutting mills) is one that efficiently cuts and grinds the leather without blocking and leaving only a small amount of unground leather. The milling chamber should be easy to open to allow cleaning between samples. During the grinding process, the speed of the cutter blade should not be excessive, so that the temperature in the milling chamber does not heat- up noticeably. To achieve these requirements, grinding mills with a small, easily accessible milling chamber and a slower blade rotation are preferred. The ground sample should readily pass through a perforated sieving plate with (4,0 ± 0,5) mm diameter perforations.
To ensure there is no contamination from heavy metals such as chromium, the metal parts of the grinding mill are made of chromium-free steel and the cutting blade is made with hardened tungsten carbide.
An example ola suitable machine is the universal cutting mill of type Pulverisette 19 with a rotational frequency o1300 mm-1 to 360 mm-1. This cutting mill is a combination of type Pulverisette 19 (original rotational frequency of 2 800 min’) and a slower motor system of type Pulverisette 25. The equipment with this combination is manufactured by Fritsch GmbH, Industriestrasse 8, D-55743 Idar-Oberstein, Germany. Website: www.fritsch-milling.com.
Any other grinding mill equipment may be used, provided it gives a ground leather sample as described above and the grinding chamber does not heat-up noticeably during grinding. Technical information on the grinding of leather is given in Reference .ISO 4044-2017 pdf free download.
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