ISO 17786:2015

Overview

ISO 17786:2015 specifies a mass analysis (gravimetric) method for determining high-temperature (105 °C) evaporation residues in dimethyl ether (DME) used as a fuel. The procedure measures non-volatile residues remaining after evaporation of approximately 100 g of liquid DME at 105 °C and reports residue as a mass percentage. The method is designed to meet the detection requirements of ISO 16861 (DME fuel specification) while using fewer resources than some alternative techniques.

Key topics and technical requirements

• Scope: Intended for DME fuel quality control to detect evaporation residues with boiling points ≥ 105 °C; residues below 105 °C are not determined by this method.
• Sampling: Samples shall be taken according to ISO 29945 (manual sampling of refrigerated, non-petroleum liquefied gases).
• Principle: Evaporate roughly 100 g total sample in a pre-weighed evaporating dish, dry at 105 °C ± 2 °C, cool in a desiccator and weigh the residue. The evaporation residue (mass %) is calculated from dish masses and sample masses.
• Apparatus & materials: stainless-steel sample cylinder (1 L, ≥ 3.0 MPa), cooling bath (dry ice + alcohol to ≤ −50 °C), evaporating dish (≥100 mL, Ø > 75 mm), oven (105 °C, no ignition source), electronic balances (sample precision ≥ 0.1 g; residue accuracy ≥ 0.1 mg).
• Procedure details: Pre-wash connecting lines with liquid DME, dose sample gradually to avoid sudden boiling, perform two aliquots (~50 g each) to reach ~100 g total, oven dry 60 min at 105 °C, cool 30 min in desiccator before weighing.
• Performance & limitations: Proven detection limit suitable for ISO 16861; precision was evaluated in a limited interlaboratory study (provisional repeatability and reproducibility). For more exact quantification, ISO 13757 is recommended.

Applications and users

• Who uses it: fuel producers, quality control laboratories, gas transport and storage operators, terminal operators, engine and burner manufacturers, and regulatory/compliance bodies concerned with DME fuel quality.
• Practical uses: verifying that DME meets residue limits in supply chains, routine QC on tank-to-tank shipments, pre-delivery checks at terminals, and troubleshooting residue-related performance issues in engines or burners. The method is useful where resource-efficient, regulatory-compliant residue testing is needed.

Related standards

• ISO 16861 - DME fuel specifications
• ISO 13757 - alternative high-temperature residue method (more precise)
• ISO 29945 - manual sampling of refrigerated liquefied gaseous fuels
• ISO 4259 - precision data methodology (statistical reference)
• Relevant industry methods: BS EN 15470/15471, ASTM D2158

Keywords: ISO 17786, DME, dimethyl ether, evaporation residue, 105 °C, mass analysis, gravimetric method, fuel quality.