Which environmentally friendly marine lubricant is the best?
author: Leila
2024-08-06
The normal operation of ships is inseparable from various lubrications. The lubricants used on ships include gear oil, turbine oil, compressor oil, hydraulic oil, refrigeration oil, guide rail oil, etc. According to the requirements, some use conventional lubricants, but some parts are in direct contact with seawater, and there is only a sealing ring between the oil and the seawater. If it leaks, it is easy to cause water pollution. Therefore, the US Environmental Protection Agency EPA stipulated four types of "environmentally acceptable" (EAL) marine environmentally friendly lubricants in 2013. These environmentally friendly lubricants can meet the following environmental protection requirements:
1. Easy to biodegrade: Within 28 days, the biodegradation rate reaches more than 60%.
2. Low toxicity to water bodies: meet the minimum requirements of the marine environment for toxicity, and the toxicity is as low as possible to reduce the impact on water bodies.
3. Non-toxic to organisms: Lubricants have no effect on organisms and food chains.
The four types of marine lubricants specified by the US Environmental Protection Agency are environmentally friendly:
Vegetable oils, such as lubricants formulated with vegetable oils such as soybean oil and rapeseed oil.
Bio-based degradable synthetic esters.
PAG (polyethylene glycol): including water-soluble and water-insoluble
Water: stern shaft tube that uses water for lubrication and cooling
Water: stern shaft tube that uses water for lubrication and cooling
The following are the performance characteristics of these common environmentally friendly lubricants:
1) Performance characteristics of vegetable oil: good lubricity, but not resistant to high temperatures, short service life, and poor low-temperature performance. Poor hydrolysis stability: easy to hydrolyze in water, and generate acidic substances and sludge, and become smelly.
2) Bio-based synthetic esters: The performance and service life of synthetic esters are better than vegetable oils, but they are easier to decompose under high temperature and high pressure, and will also decompose in water.
3) PAG is not actually an oil, so it will not form oil marks on the water surface, and it is non-toxic. The US Environmental Protection Agency (EPA) lists PAG as an environmentally friendly lubricant because PAG is biodegradable and has very low toxicity to water bodies.
In addition to the environmental advantages, PAG also has excellent performance: PAG's lubricating film has a strong load-bearing capacity, the "oil film" is strong, high temperature resistant (up to 120°C), fireproof, slightly denser than water (specific gravity of about 1.03), and divided into water-soluble and non-water-soluble. After being discharged, water-soluble PAG can be dispersed in the water body without forming an oil belt, reducing the impact on the water body.
PAG has excellent oxidation stability and long service life. Hydraulic oil and gear oil based on PAG have excellent antioxidant ability, and good antioxidant performance is critical to the service life of lubricants. In addition, PAG will not generate solid impurities such as carbon deposits or paint films at high temperatures.
PAG's water resistance and anti-rust ability: Through the design and modification of PAG molecules, the desired characteristics can be obtained. Through the demand for ship lubrication and environmental protection requirements, PAG has been transformed into an ideal lubricant for marine lubricants. The hydrolysis stability of vegetable oil and synthetic ester is not good, but the hydrolysis stability of PAG is much higher, and the water content that can be tolerated is as high as 1.5% (15000ppm). Most mineral oils and synthetic oils have a tolerance of only about 200ppm for water. The main effect of excessive water intake on PAG is a decrease in viscosity and lubricity. PAG solution also has a good ability to prevent corrosion and rust.
PAG service life: It also has a long service life, so it can be used for a long time after a change, reducing the trouble of replacement. From all aspects, PAG can not only meet environmental protection requirements, but also ensure excellent lubrication performance.
Many people think that the price of PAG is relatively high, but if you consider the performance and use time of all aspects, it is actually cost-effective. Besides, other types of environmentally friendly oils on the market are not cheap. At present, PAG is a good product in all aspects, which not only meets environmental protection requirements but also has excellent lubrication performance. With the development of science, environmentally friendly lubricants will also have new progress. Perhaps there will be new products that surpass PAG. Let us wait and see.
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