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ISO 249:2014 pdf free

ISO 249:2014 pdf free.Rubber, raw natural – Determination of dirt content
ISO 249 specifies a method for the determination of the dirt content of raw natural rubber.
It is not applicable to dirt present as surface contamination.
The following documents, in whole or in part, are normatively referenced in this document and are indispensable for its application. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies.
ISO 565, Test sieves一Metal wire cloth, perforated metal plate and electroformed sheet一Nominal sizes of openings
ISO 1795, Rubber, raw natural and raw synthetic一Sampling and further preparative procedures
WARNING一All recognized health and safety precautions shall be exercised during the operations of this analysis, with particular emphasis on safe handling of the flammable solvents required. All solvents shall be free from water and dirt.
During the analysis, wherever possible, use only reagents of recognized analytical grade.
Heater, for heating the conical flask or beaker (4.1) and its contents (see the Note to 5.3.4).
Hotplates which provide uniform heating surfaces, or infrared lamps, are recommended. Infrared lamps (250 W) can be placed in rows, with the base of the conical flask about 20 cm from the top of the lamp. Individual control of each lamp is recommended to prevent localized overheating. Alternatively, a
sand bath may be used.
Sieve, of nominal size of openings 44 μm to 45 um (325 mesh) of corrosion-resistant wire gauze, preferably stainless steel, complying with ISO 565.
The wire gauze shall be mounted across the end of a metal tube about 25 mm in diameter and greater than 20 mm long.
The sieve shall be constructed in such a way that the gauze is free from distortion and is protected from accidental damage. A suitable construction is shown in Figure 1.
Sieves and holders may also be constructed by removing the bottom of a metal crucible having the appropriate dimensions, and soldering the screen to the crucible. This results in an ample container for the rubber solution during filtering.
A coarse screen may also be soldered under the 44 μm to 45 um (325 mesh) gauze to protect it from accidental damage. This“guard” screen shall not hinder the filtration in any way but only provide a support for the gauze.ISO 249 pdf download.

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