Reasons and treatment methods for excessive acid value of fire resistant oil (EH oil)
September 22, 2023
1. What is fire-resistant oil Fire resistant oil (EH oil) is composed of phosphate esters, with a transparent and uniform appearance. The new oil is slightly light yellow, without sediment, has low volatility, good wear resistance, stability, and physical stability. The fire-resistant fuel used in the electro-hydraulic control system of power plants is a pure phosphate liquid that is resistant to combustion. Its flame retardancy is one of the most prominent characteristics of phosphate esters, and it can burn even at extremely high temperatures. However, it does not spread flames or can quickly self extinguish after ignition. Phosphate esters have high thermal oxidation stability. 2. Hazards of exceeding the acid value of fire-resistant oil (EH oil) Acid value is a chemical indicator that reflects the degree of deterioration of fire-resistant oil. An increase in acid value indicates that the fire-resistant oil has produced acidic substances due to degradation (oxidation hydrolysis). The acid value should be controlled within the operating oil index of 0.10mgKOH/g, and oil quality is unstable if the acid value exceeds 0.1mgKOH/g. A high acid value of EH fire-resistant oil will accelerate the hydrolysis of phosphate ester fire-resistant oil, thereby shortening the lifespan of the fire-resistant oil. Therefore, the lower the acid value, the better. At the same time, the increase of acid value will cause corrosion of system components and affect the lubricating characteristics of the oil. Moreover, the increase of acid value indicates that the oil has deteriorated and there are deterioration products in the oil, that is, mineral oil derivatives (sludge) are generated. These deterioration products will affect the resistivity, particle size, foam and air release value of the oil to varying degrees, making the oil turbid and reducing the fire resistance;
3. Reasons for exceeding the acid value of phosphate ester flame resistant oil Fire-resistant oil, like mineral oil, undergoes oxidation reactions when exposed to oxygen and temperature, producing acidic compounds (sludge). The higher the sludge, the faster the rate of acid production. In addition, fire-resistant oil has an additional chemical reaction compared to mineral oil, which is hydrolysis reaction. After encountering water, fire-resistant oil undergoes hydrolysis, which generates acidic substances such as phosphoric acid or hemiphosphoric acid. The combination of oxidation and hydrolysis reactions results in a faster increase in the acid value of fire-resistant oils compared to mineral oils, with temperature and moisture being the main factors contributing to the increase in acid value. 4. Treatment method for exceeding the acid value of phosphate ester flame resistant oil Adhering to long-term or regular online oil filtration and purification, and regularly replacing the filter element of the oil filter, can effectively control the growth of acid value. For example, the Chongqing Qinneng brand fire-resistant oil filter can control the acid value of the fire-resistant oil to not exceed 0.10mgKOH/g for long-term operation. The indicators after being processed by the oil filter are as follows: Acid value, ≤ 0.10 mgKOH/g (detection method GB/T 264) Particle pollution level NAS1638 ≤ 6 (detection method SD 313) Moisture, mg/L ≤ 600 (Test Method GB/T 7600) Resistivity 20 ℃, ≥ 6 × 109 Ω. cm (detection method DL 421)
