BS ISO 23381:2020 pdf download

BS ISO 23381:2020 pdf download

BS ISO 23381:2020 pdf download.Determination of salt out (crystallization) temperature of liquid fertilizers
1 Scope
This document specifies the test procedure for the determination of the salt out temperature (SOT), also known as the crystallization temperature (CT) of liquid (fluid) fertilizers, using an inexpensive and simple technique. This method might not be applicable to the binary and ternary fertilizers, especially with regards to the last crystal to disappear (LCTD). Some of these exceptions are discussed in the procedure (Clause 8).
2 Normative references
The following referenced 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 3696:1987, Water for analytical laboratory use — Specification and test methods
3 Terms and definitions
No terms and definitions are listed in this document.
ISO and IEC maintain terminological databases for use in standardization at the following addresses:
— IEC Electropedia: available at
— ISO Online browsing platform: available at
4 Principles
Liquid fertilizers have been defined in ISO 8157:2015. An aliquot of the original liquid fertilizer sample is placed into a glass test tube and is then immersed into an alcohol-dry ice bath until it crystallizes. The alcohol could be chosen from methanol, ethanol, or isopropanol (IPA). Acetone could also be used instead of alcohols; however, IPA (rubbing alcohol) is preferred due to its higher boiling point. If dry ice is not available, other lowering temperature mixtures such as salt-ice could be used to achieve the proper cooling and crystallization of the fertilizer test sample. Once the precipitation (formation of salt crystals) is complete, the cooling source is removed and the glass test tube and its contents are allowed to warm up to room temperature. The SOT in most cases is defined when the last crystal to dissolve (LCTD) dissolves (i.e. is no longer visible in the solution). Exceptions to the LCTD rule are covered below and in 8.11. The underlying principal of the technique can be illustrated with the following cooling curve [9] shown in Figure 1.
5.1 Use only water conforming to grade 3 of ISO 3696:1987.
5.2 Dry ice snow maker (cone, clamp, ring, and thermal bag), or supply of dry ice.
5.3 CO 2 cylinder with a dip tube for making dry ice (or supply of dry ice).
5.4 IPA or other appropriate solvents such as methanol, ethanol, or acetone.
5.5 If dry ice is not available, other cooling systems such as an ice-salt bath could be used. However,
care must be taken to achieve a proper low temperature.
6 Equipment
6.1 1 × stir motor apparatus 1) .
6.2 3-Jaw Keyless Chuck with Arbor 2) .
6.3 1 × 2-foot steel rod with attachable base 3) .
6.4 1 × three-prong clamp.
6.5 2 × Silver-lined Dewar Vacuum Flask with cap 4) .
6.6 50 cm 3 glass test tubes (several, Pyrex or similar quality).
6.7 Thin Stainless steel wire (several inches, such as 40 AWG, 0,079 9 mm, or 30 gauges, 0,010 inch, or 24 gauges, 0,58 mm).
6.8 Thin walled latex rubber tubing (several inches).
6.9 1 × thermometer (−40 °C to a least +30 °C), red liquor preferred for ease of reading. Alcohol filled thermometers are preferred over mercury-in-glass thermometers due to safety concerns with mercury.It is recommended that several alcohol thermometers with different temperature ranges be available.