SIAM's now-withdrawn letter: What the science says about chloride, moisture and your E20 petrol
Industry body flagged chloride and moisture contamination. HT explains why chloride corrodes and why moisture matters in ethanol-blended petrol.
The Society of Indian Automobile Manufacturers (SIAM) recently withdrew a letter it had sent to the Union ministry of petroleum and natural gas (MoP&NG) regarding chloride and water contamination in E20 fuel, which is a blend of 20% ethanol and petrol. The letter had claimed that chloride and moisture were present in fuel samples and that the issue stemmed from the supply chain rather than the E20 formulation.
However, SIAM later clarified that the industry had always supported the government's E20 initiative, and the measures taken by oil marketing companies (OMCs) and the ministry were sufficient to meet the industry's needs.
The withdrawal of the letter occurred amid protests by AAP convener Arvind Kejriwal, who demanded that the government provide options for using only-petrol alongside ethanol-blended fuel. The Modi-led government has consistently maintained that E20 is safe for use, does not damage vehicle engines, and results in only a slight reduction in mileage.
SIAM's letter cited cases of damage to auto-parts in direct contact with fuel or combustion gases, such as fuel injectors and exhaust gas recirculation (EGR) valves, which showed signs of corrosion and wear consistent with chloride exposure. The letter described two patterns: corrosion-linked wear in fuel-system parts and stalling shortly after refuelling, which was attributed to phase separation caused by high moisture in fuel.
Chloride ions can attack the protective oxide film on stainless steel, aluminum, and their alloys, leading to pitting corrosion and stress-corrosion cracking. These issues are particularly harmful to fuel injectors and pumps, which rely on micron-level orifices for fuel delivery. The chloride contamination in ethanol can originate from water used in distillation, caustic soda for pH balancing, transport equipment, and denaturants.
The US standard for chloride in ethanol is 8 parts per million (ppm), while the Indian standard does not specify a limit.
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