BS 6043-1.1:2002 pdf download – Methods of sampling and test for carbonaceous materials used in aluminium manufacture — Part 1: Electrode pitch — Section 1.1: Sampling
4 General procedures and precautions
4.1 Sampling methods Manual and automated sample-taking are equally acceptable. Details of the methods employed shall be described in the sampling report (see clause 1 0).
4.2 Contamination of sample or of pitch being sampled The sampling procedure shall not cause contamination of the sample or of the pitch being sampled. Sample containers, sampling apparatus and any ancillary gear shall be dry. Sample containers, sampling apparatus, any ancillary gear, the hands and gloves and the protective clothing of the sampler shall be clean. Pitch undergoes slow surface oxidation in the presence of air. Finely divided products, because of their large surface area per unit mass, may show a significant rise in softening point even if stored for only a short time. It is recommended therefore that finely divided reference samples be prepared for storage by melting and resolidifying as follows.
a) Place a sufficient amount of the powdered sample in a suitable container with a loose-fitting lid in an oven controlled at approximately above the expected softening point of the pitch. Leave in the oven for at this temperature. After heating, the surface of the melt should be smooth, shiny and free of skin.
b) If the surface of the melt is covered with froth, suggesting the presence of water, discard it and prepare another melt using a further portion of the sample which has first been dried by allowing it to stand in an evacuated desiccator in the presence of a suitable desiccant for approximately .
c) Pour the molten pitch without turbulence, so as to avoid entrapping air bubbles, into an air-tight metal container, allowing it to solidify and seal the container.
d) Note any froth formation during melting in the sample report and, in such cases; retain a separate portion of the finely-divided sample, stored in a sealed air-tight container, for the determination of water content. If a sample container is opened, it shall be securely closed again as soon as possible and any damaged sealing rings shall be replaced.
4.3 Sampling for the determination of water content of pitch in solid form For bulk shipments of solid pitch, a series of spot samples shall be taken for determination of water content, either from the conveying system during charge or discharge, or from the hold or compartment, or lorry at the top, middle or bottom during charge or discharge. The individual samples shall be sealed immediately in air-tight containers and tested promptly to avoid loss of moisture.
4.4 Mass of laboratory and reference samples The mass of the laboratory and reference samples shall be at least three times the amount required for testing and shall never be less than unless otherwise agreed in accordance with an established quality procedure. The sample mass shall be included in the sampling report (see clause 1 0). The minimum recommended sample mass is .
4.5 Safety precautions Comprehensive safety instructions are given in ISO 31 65. Attention is drawn in particular to the following.
— When sampling hot liquid pitch from large containers such as ships, road or rail tanks, the sampler shall closely follow the safety procedures laid down for that site or location. These procedures typically include protective equipment and guidelines on safe working practice.
— Avoid inhalation of pitch vapour and dust.
— Sampling from ships, road or rail vehicles shall be strongly discouraged when in motion or when motion is likely to begin.
4.6 Suspect consignment
A consignment shall be considered suspect if:
a) a container is damaged or defective;
b) there is any doubt as to the nature of the contents of a container, for example because of the presence of an old label or incorrect markings;
c) there is evidence of an unexpected lack of uniformity;
d) there are obvious and unusual variations observed in the consignment.