What are the diesel fuel testing indicators?
4 Answers
Here is an introduction to diesel fuel testing indicators: 1. Oxidation stability: Determined according to SH/T0175 method. Method summary: Filter 350mL of sample, inject it into an oxidation tube, pass oxygen at a rate of 50mL/min, and oxidize at 93°C for 16 hours. Then cool the oxidized sample to room temperature and filter to obtain filterable insolubles. 2. Sulfur content: Determined according to GB/T380 method. Method summary: Burn an appropriate amount of sample in a lamp, absorb the generated sulfur dioxide with a 0.3% sodium carbonate aqueous solution, and titrate the absorption solution with 0.05N hydrochloric acid standard solution using bromocresol green methyl red as titration indicator. 3. Acidity: Determined according to GB/T258 method. Method summary: Volumetric method. This method uses boiling ethanol to extract organic acids from light diesel, then titrates while hot with 0.05N potassium hydroxide ethanol solution. The milliliters of potassium hydroxide required to neutralize 100 milliliters of petroleum product is called acidity. 4. Carbon residue: Determined according to GB/T268 method. Method summary: Place an appropriate amount of sample in a crucible for decomposition distillation. The residue undergoes intense heating for cracking and coking reactions. After heating for 30±2 minutes, the carbon residue value is calculated based on the mass of carbonaceous residue. 5. Ash content: Determined according to GB/T508 method. Method summary: Place no more than 100 grams of sample in a pre-weighed crucible, heat on an electric hot plate using an ashless filter paper as wick, burn until only ash and carbon residue remain, then place in a 775±25°C high-temperature furnace for 1.5~2 hours. The ash result is obtained by weighing.
I've been driving a diesel car for five or six years and pay special attention to fuel quality. High sulfur content in diesel can easily clog the DPF (Diesel Particulate Filter), and repairing it can cost several thousand yuan. Fuel with excessive water and mechanical impurities is particularly damaging to the fuel injectors, and repairing a set now can cost over ten thousand yuan. If the cold filter plugging point is too low, the fuel lines can wax up in winter. Once, my car broke down in Northeast China, and the engine almost froze. The cetane number is crucial—if it's too low, the car lacks power and emits black smoke. I've tried using low-quality fuel before, and the car wouldn't move even with the accelerator fully pressed while climbing a hill. The density should ideally be around 0.83. Fuel pump errors at gas stations can reach up to 2%, so a difference of one liter when filling 50 liters isn’t uncommon. When choosing a gas station, I always check their test reports, especially the pour point and flash point. A flash point below 45 degrees makes the fuel too prone to catching fire in summer.
We test diesel fuel in the oil depot every day, focusing on several key safety indicators. We use a trace moisture detector to check water content—exceeding the limit by 0.05% can corrode fuel tanks, but gas stations now have filters to intercept it. Impurity testing is critical, especially for particles smaller than 5 microns in diameter, as excessive accumulation can wear out high-pressure fuel pumps. Sulfur content is tested on-site with rapid detection—if it exceeds 10ppm, we reject the shipment, since using high-sulfur fuel in a China VI vehicle can trigger a fault light within three days. The flash point must be ≥60°C; last week, we tested a batch at only 52°C and immediately returned it. The pour point is adjusted seasonally—northern winters require it to be below -20°C. Cetane number is measured with an instrument; vehicles with values below 45 may experience hard starts. Excessive density can lead to measurement disputes, with customers complaining about insufficient fueling. With many transient customers, we take samples every two hours.
Having been in long-distance freight for over a decade, I've encountered countless diesel fuel issues. The most critical indicator is the cold filter plugging point - last month in Mohe at -35°C, my fuel gelled up and left me stranded for two hours. Cetane number is crucial; low-grade fuel causes weak acceleration and increases fuel consumption by 20%. I always carry test strips to check sulfur content - high-sulfur fuel corroded my fuel lines, requiring three repairs. The pour point must match regional temperatures; using #0 diesel on the Qinghai-Tibet route guarantees freezing. Opt for 0.84 density fuel - it burns longer and saves shipping costs. Water content is the trickiest - contaminated storage tanks at gas stations are common, and spotting water in fuel means immediate tank cleaning. Excessive impurities clog fuel filters; I replace mine every 5,000 km. Poor diesel quality directly impacts engine performance and maintenance costs.
