BS EN ISO 7027 pdf free download

BS EN ISO 7027 pdf free download. Water quality – Determination of turbidity.
4? Sampling and samples Maintain all containers that come into contact with the sample in a scrupulously clean condition. Wash with hydrochloric acid or surfactant cleaning solution. Collect samples in glass or plastics bottles, and carry out the determinations as soon as possible after collection. If storage is unavoidable, store the samples in a cool, dark room but for not longer than 24 h. If the samples have been stored cool, allow them to come to room temperature before measurement. Prevent contact between the sample and air, and avoid unnecessary changes in the temperature of the sample. 5? Semiquantitative methods of turbidity measurement 5.1? Measurement using the transparency testing tube 5.1.1? Apparatus 5.1.1.1? Transparency testing tube, consisting of a colourless glass tube 600 mm ? 1 0 mm long and of internal diameter 25 mm ? 1 mm, graduated in divisions of 1 0 mm. 5.1.1.2? Shield, close-fitting, to protect the transparency testing tube from lateral light. 5.1.1.3? Print sample to place under the tube (5.1 .1 .1 ), consisting of black print on a white background (height of characters 3,5 mm; line width 0,35 mm) or a test mark (for example, a black cross on white paper), provided with the apparatus. 5.1.1.4? Constant light source, 3 W low voltage tungsten lamp, to illuminate the print sample or test mark (5.1 .1 .3). 5.1.2? Procedure It is absolutely essential that tests conducted according to this International Standard be carried out by suitably qualified staff. Thoroughly mix the sample and transfer it to the transparency testing tube (5.1 .1 .1 ). Steadily lower the sample level until the print sample or test mark (5.1 .1 .3) is clearly recognizable as viewed from above. Read the liquid height from the graduations on the tube. 5.1.3? Expression of results Report the measured liquid height, to the nearest 1 0 mm, together with the apparatus used (name of the manufacturer). 5.2? Measurement using the transparency testing disk NOTE? This method is intended primarily for testing bodies of water in situ. 5.2.1? Apparatus 5.2.1.1? Transparency testing disk made of cast bronze and coated with white (see ISO 3864) plastics, attached to a chain or rod. NOTE? A typical design comprises a disk of diameter 200 mm with six holes, each of diameter 55 mm, on a circle of diameter 1 20 mm. 5.2.2? Procedure It is absolutely essential that tests conducted according to this standard be carried out by suitably qualified staff. Lower the disk, on its chain or rod, into the water until the disk is barely visible when viewed from above. Measure the length of immersed chain or rod. Repeat the test several times. Ensure that no interference arises from reflection at the water surface. 5.2.3? Expression of results Report the depth of immersion. For values less than 1 m, report the result to the nearest 1 0 mm. For values greater than 1 m, report the result to the nearest 0,1 m. 6? Quantitative methods of turbidity measurement using optical turbidimeters 6.1? General principles It is absolutely essential that tests conducted according to this International Standard be carried out by suitably qualified staff. To obtain the spectral diffusion coefficient s(?) alone, the spectral absorption coefficient ?(?) needs to be known. In order to determine the spectral absorption coefficient of the dissolved substance, the undissolved substances can, in some cases, be removed by filtration, but this may cause interferences. Therefore, it is necessary to report the results of the determination of turbidity in comparison to a calibration standard.BS EN ISO 7027 pdf download.