Overview
EN ISO 16995:2015 - Solid biofuels - Determination of the water soluble chloride, sodium and potassium content (ISO 16995:2015) describes a standardized laboratory method to extract and quantify the water‑soluble fractions of chloride, sodium and potassium from solid biofuels. The method uses a closed‑vessel water extraction (120 °C, 1 h) followed by analytical determination by ion chromatography, potentiometric titration, flame emission/absorption or ICP‑OES. The standard supersedes EN 15105:2011 and is intended for consistent, comparable biofuel testing across laboratories.
Key topics and technical requirements
- Scope: Determines the amount extractable with water (water‑soluble chloride, Na, K) - not the total element content. Relevant to salt forms that are mobile and volatile during combustion.
- Extraction procedure:
- Sample: 1.0 g (nominal top size ≤ 1 mm, prepared per EN 14780).
- Add 50.0 ml deionized water in a fluoropolymer vessel (≈100 ml) with tight cap.
- Heat closed vessel at 120 ± 5 °C for 60 min, cool, dilute to 100 ml, filter (0.45 μm).
- Analytical methods:
- Chloride: Ion chromatography (IC) or potentiometric titration with AgNO3 (note: titration includes water‑soluble bromide and iodide).
- Sodium & potassium: Flame emission spectroscopy (FES), flame atomic absorption spectrometry (FAAS) or ICP‑OES.
- Apparatus & reagents: Oven/autoclave capable of 120 °C; fluoropolymer vessels resistant to ≥125 °C/232 kPa (borosilicate glass acceptable when testing chloride only); deionized water with negligible Cl/Na/K; balance with ≥1 mg resolution.
- Quality elements: Concurrent moisture determination (ISO 18134‑3) when results are converted to other bases; blank tests, filtration, and reporting requirements. Performance characteristics and test report structure are specified.
Applications and users
- Practical for: biofuel producers, independent testing laboratories, boiler and CHP plant operators, fuel traders, environmental regulators and researchers.
- Use cases:
- Assessing risk of corrosion, fouling and slagging in combustion systems.
- Estimating volatile, aggressive fractions of Na and K that influence emissions and ash behavior.
- Quality control and specification compliance for wood chips, pellets, straw and other solid biofuels.
Related standards
Keywords: EN ISO 16995:2015, solid biofuels, water soluble chloride, sodium and potassium determination, biofuel testing, ion chromatography, ICP‑OES, potentiometric titration, extraction 120 °C.