This technical guide for sampling is applicable to thermal and wet ortho- and polyphosphoric acids, as well as crystallized phosphoric acids. Sampling wet acids is particularly delicate due to the frequent presence of a precipitate that is more or less abundant and more or less difficult to suspend.
NBN T 03-271-1980 history
1980NBN T 03-271-1980 Phosphoric acid for industrial use - Guide to sampling techniques