ISO 29945:2009 specifies a manual sampling method for refrigerated liquefied DME at terminals in both loading and unloading ports. ISO 29945:2009 also specifies detailed precautions to ensure safety during sampling work. However, safety measures, proposed for equipment being used for sampling, such as sampling lines and sample cylinders, are limited to general terms because they are governed mostly by national regulatory requirements.
ISO 29945:2009 does not include recommendations for the location of a sampling point in a line or vessel.
It is the responsibility of the user to ensure that sampling point is located so as to obtain a representative sample. However, to prevent vaporization of DME in the line before sampling, it is preferable to locate the sampling point at a place where the pressure and temperature of the DME in the line is kept constant to ensure obtaining a sample from the liquid phase only.
ISO 29945:2009 is also applicable to the following cases, with necessary modifications:
- sampling of DME on board liquefied gas tankers where appropriate sampling apparatus is provided;
- sampling of other refrigerated, non-petroleum-based, liquefied gaseous fuels whose chemical and physical properties are similar to those of DME.
The detailed chemical and physical properties of DME differ from those of LPG, which suggests that DME requires precautions different from those of LPG. However, their basic properties are similar to each other and so general reference is made in ISO 29945:2009 to precautions for LPG that have been applied in many countries. Reference can also be made to the appropriate individual items in this International Standard for precautions concerning the quality.