The Status of Bio-Fluids: Using Green Lubricants without Sacrificing Performance
Chemical Engineer Raffaele Fanelli performs viscosimetrics testing at the Panolin laboratory. The testing on this machine determines viscosity (thickness) of fluid at 40°C (104°F) and 100°C (212°F).
Graph 1. Viscosity increases vs. temperature of various oils - rapeseed oil (HETG), olleate (HEES, unsaturated ester), and Panolin HLP Synth (HEES, saturated ester).
Graph 2. Tests monitor oils for losses in oxidation resistance and increases in acid levels.
Graph 3. Standard Mineral Oil requires regular drain intervals; Panolin is a lifetime fill fluid.
Panolin performs IR (infrared spectroscopies) on this machine. The infrared spectrum compared against the spectrum of a relevant reference oil provides information about changes in the oil or possible oil contamination. For example, the level of oil deg
Globally, regulations are being passed requiring those who work in or near waterways – rivers, ponds and oceans – to respect and preserve the wildlife calling that place home.
In the face of growing restrictions, users of hydraulic equipment are being required to use biofluids that are more expensive than traditional oils, without understanding the differences between the many fluid options available.
One solution is Panolin HLP Synth – a fully synthetic, high-performance, readily biodegradable, non-toxic hydraulic fluid made from saturated esters. It is combined with high-grade additives, is zinc-free and therefore also environmentally friendly. The product leaves no sheen when it is spilled on the water, but rather appears as light foam that is visible for easy cleanup. It is able to resist oxidation at high temperatures and high pressures, and prevents gumming and deposits in the hydraulic system.
Panolin does not affect conventional sealing materials, and it provides excellent corrosion resistance and wear-protection.
What Constitutes ‘Green’?
The two most sought after characteristics in hydraulic oils for marine use are biodegradability and non-toxicity. The classifications for biodegradability have been so convoluted by fluid manufacturers that the answer is no longer clear.
There are two classifications of biodegradability – inherently biodegradable and readily biodegradable. All fluids are biodegradable, meaning they break down within some undefined span of time. The U.S. Army Corps of Engineers has defined test conditions in method OECD (Organization for Economic Co-Operation and Economic Development) 301B, stating that a hydraulic fluid is classified as readily biodegradable when 60 percent or more of the material is decomposed in 28 days. (1)
Because a fluid is biodegradable does not also mean that it is non-toxic. The U.S. Army Corps of Engineers has defined test conditions for toxicity in OECD 203, stating that a hydraulic fluid is considered non-toxic if a specific ratio of the hydraulic fluid to water is used, and less than 50 percent of the test organisms die within 96 hours. (1) To meet most regulations, both the standards for biodegradability and toxicity must be met.
Biofluids can be broken down in to four major classifications: HEPG, HETG, HEPR and HEES fluids.
HE stands for “hydraulic environmental,” as defined by ISO-15380. HEPG is polyglycols; HETG is triglycerides; HEPR is polyalphaolefins; and HEES is synthetic esters.
HEPG fluids or polyglycols may be water- or oil-based, but are not miscible with other lubricants, and commonly have issues with seal compatibility. HETG fluids are plant- or animal-based fluids. These fluids are biodegradable, but generally have issues tolerating high heat levels over time. The third type, HEPR or polyalphaolefins, have good hydrolytic stability and biodegradability, but may lose their viscosity as they are run through a hydraulic system over time. (See Graph 1)
The final classification of biofluids is the HEES or synthetic ester fluids. Unfortunately, HEES fluids are often generalized into one major category despite major differences in performance and longevity between the two types. These fluids can be broken up into two categories – saturated and unsaturated esters. Whether or not the product is saturated is determined by the chemical bonds within the fluid itself. Unsaturated esters have multiple open bonds which interact with oxygen quickly, leading to oxidation, or aging, of the fluid. This aging is the cause of extreme thickening and gumming of the fluid, along with deposits and shellac, which lead to major catastrophic system failures.
Saturated ester products, however, contain significantly fewer open bonds, and therefore they do not oxidize and will last much longer in high-heat, intense applications. How can you tell the difference? Look at the iodine number, which identifies the number of open bonds available, so the higher the iodine number, the greater the number of bonds that can interact and oxidize. Generally speaking, a saturated ester product has an iodine number less than 15.
Taking it to the Limit
The most common tests for the life of a fluid are the RPVOT (ASTM D2272 or Rotating Pressure Vessel Oxidation Test), the Cincinnati Milacron Test (ASTM D2070) or TOST (ASTM D943). These tests are used to subject fluids to the worst conditions possible, in an effort to force them to oxidize.
These tests will monitor oils for losses in oxidation resistance and increases in acid levels. (See Graph 2) (2)
The TAN, or Total Acid Number, is a common test which indicates the level of deterioration or break-down of a hydraulic fluid. A high or increasing TAN number indicates that your fluid is oxidizing or hydrolysis is taking place. Monitoring the TAN levels in a hydraulic system can provide an early indication of a potential problem, and allow preventative maintenance to be conducted on the system as needed, saving both time and money.
Providing a Solution
Panolin HLP Synth has a lifetime fill capability. Due to its base composition and saturated nature, Panolin does not break down over time. Thus, this fluid is able to last within a hydraulic system for extremely long periods of time without any oil-change requirement, decreasing downtime and maintenance costs. Test documentation shows that some clients have been using Panolin in their machines for over 130,000 hours (that’s operating 24 hours per day for nearly 15 years) without ever changing the fluid. (See Graph 3)
Panolin & Performance
Panolin has been used in and along waterways around the globe for decades, in applications from offshore cranes to remotely-operated subsea vehicles. Its popularity is growing rapidly in the United States, as lower maintenance costs and meeting environmental regulations become increasingly important. Many companies have already started using Panolin products in an effort to promote their green image and gain contracts with clients because of their environmentally-friendly systems, turning to Panolin for a biodegradable, non-toxic alternative to mineral oils, and offering exceptionally long life in the most rigorous applications.
Not all fluids are created equal, and it is important to understand the differences when selecting your biofluid. If you have any questions related to your current biofluids, general biofluid selection, or would just like to put your biofluid to the test, please feel free to contact Panolin or Hydraquip and we will be happy to assist you.
(1) “EM 1110-2-1424 (28 February 1999).” Publications, US Army Corps of Engineers. 28 Feb. 1999. Web. 24 June 2011. http://188.8.131.52/publications/eng-manuals/em1110-2-1424/toc.htm.
(2) Ruch, Martin. “Panolin Atlantis - Panolin HLP Synth.” Message to the author. 24 June 2011. E-mail.
ABOUT THE AUTHOR
Chauntelle Baughman is account manager for Hydraquip Distribution, Inc., Houston, Texas. She is available to answer questions on biofluids. Contact her at: 713-680-1951 or email: firstname.lastname@example.org.