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Friday, 10 August 2012
11:20 | Posted by Habot | | Edit Post
Biodegradble lubricants should be considered where there’s a high risk of environmental damage
Marine, forestry and agriculture industries in particular, along with citizen groups and
governments, are becoming more and more concerned about reducing the effect of oil on the environment. And the use of biodegradable oils can help to maintain the environment and even relieve some of the demand on mineral oils in the future.
Vegetable oils are environmentally friendly, and form the major source of biodegradble lubricants.
- They can have excellent lubricity, far superior to that of mineral oil. In fact, their lubricity is so potent that in some applications, such as tractor transmissions, friction materials must be added to reduce clutch slippage. This group also have a very high viscosity index (VI). For example, a VI of 223 is common for vegetable oil, compared to 90 to 100 for most mineral oils, about 126 for polyalphaolefin (PAO) and 150 for polyglycol. (Viscosity index can be defined as a frequently used measure of a fluid’s change of viscosity with temperature. The higher the viscosity index, the smaller the relative change in viscosity with temperature. In other words, oil with a high VI changes less with temperature than oil with a low VI.)
- Another important property is the high flash point. Typically, this might be 326 degrees C (610 degrees F) for a vegetable oil, compared to a flash point of 200 degrees C (392 degrees F) for most mineral oils; 221 degrees C for polyalphaolefin (PAO) and 177 degrees C for polyglycol. (Flash point can be defined as the temperature to which a combustible liquid must be heated to give off sufficient vapor to momentarily form a flammable mixture with air when a small flame is applied under specified conditions, according to ASTM D92.)
But how are biodegradble lubricants defined?There are several specifications that lubricants have to meet in order to be accepted as biodegradble lubricants:
- Using tests developed by the American Society for Testing and Materials (ASTM) and the Organization for Economic Cooperation and Development (OECD), a sample of the biodegradble lubricant oil is inoculated with bacteria and kept under controlled conditions for 28 days. The percentage of oxygen consumption or carbon-dioxide evolution is monitored to determine the degree of biodegradability of the oil. Most vegetable oils have shown to biodegrade more than 70 percent within that period, as compared to petroleum oils at nearly 15 to 35 percent. For a test sample to be considered a biodegradble lubricant, there must be more than 60-percent degradation in 28 days.
- Similarly, by using a variety of tests involving fish, daphnia and other organisms, the toxicity of vegetable oils can be measured. In this case, both mineral oil and vegetable oil in their pure forms show little toxicity, but when additives are included, the toxicity increases.
Whether or not you believe biodegradble lubricants should be considered for an application in your plant, you can always consult the professionals at Habot Synthetic Lubricants for a solution.
Labels: biodegradable oils, Biodegradble lubricants should be considered, mineral oils, vegetable oils