Powered by Blogger.
Friday, 25 July 2014

The problems with biodegradable oil.

Before using, make sure you’re aware of the problems with biodegradable oil.

Although strongly promoted by environmentalists there are nevertheless a few problems with biodegradable oil that renders it unusable in many applications. Before considering using biodegradable lubricants it’s important that you first understand what the problems with biodegradable oil are.

In order to understand the problems with biodegradable oil we need to understand the differences.

Vegetable oils: 
These oils are extracted from various plants such as: corn, soybean, rapeseed (canola), sunflower, peanut, olive oil amongst others. The problems with biodegradable oil obtained from these are their poor thermal, hydrolytic and oxidation stability.
  • Being organic, natural vegetable oils cannot withstand tank temperatures over 80ºC. 
  • Added to this, water, even in small quantities of around a few hundred parts per million, is extremely detrimental to vegetable oil functionality and can result in serious frothing and degradation problems. Over-all, these oils also suffer from low cold-flow abilities. 
  • Another disadvantage vegetable oils have to contend with, are their high pour point. However, this problem can be overcome with the addition of chemical additives (pour point suppressants) and/or blending with other fluids with lower pour points. 
To overcome these problems with biodegradable oil where a great level of biodegradability is required, the lubricant can be modified by adding biodegradable synthetic esters to enhance cold-temperature performance.

However, if the biobased properties of the oil need to be preserved, where biomaterials make up at least 51 percent of the lubricant, then a fraction of the blend could be made up of a light mineral oil with a low pour point to overcome these problems with biodegradable oil.

Synthetic Esters: 
 These lubricants are based on natural and renewable resources or fully synthetic esters based on petrochemical raw materials. These synthetic oils have strong antioxidation characteristics and seal-swell characteristics.

Synthetic Polyalphaolefines (PAO): 
These biodegradable oils have excellent low-temperature properties, but because they tend to shrink rubber-seal material users could have problems with biodegradable oil based on Polyalophaoline’s.

Synthetic Polyglycols (PAGs): 
These polyglycol oils can either be water soluble (ethylene-oxide) or water insoluble (propylene-oxide).

If fire-resistant lubricants are required PAGs are usually specified. Although the problems with biodegradable oil, in the form of PAG, is the tendency to emulsify water in certain equipment, such as gear boxes which leads to foaming, sludge and corrosion.

Another problem encountered when using both PAOs and PAGs is their poor solubility with certain additives.

Depending on the application and the environmental performance requirements most manufacturers use blends of the above base fluids to overcome these notable problems with biodegradable oil.

When engineering environmentally acceptable lubricants esters are usually chosen as the base fluid.

How to avoid problems with biodegradable oil.

If biodegradable lubricants have to be used it’s important to select the correct oil for the application in order not to run into problems with biodegradable oil.

Because the correct selection is critical to avoid problems with biodegradable oil it’s important that professional advice is sought: Habot Synthetic Lubricants are manufacturers of high quality synthetic oils and are able to give you advice on the best lubricant for the application.