Lousiana, USA-based crane rental and dealer Scott Powerline bought the National ENVI 690EU boom truck whose hydraulic system was filled with vegetable-based hydraulic oil. “The reason we bought it was that they were using it in the Lousiana wetlands where you couldn’t have oil spills,” says fleet manager Dillard Winn.
“These cranes don’t leak much,” he adds, “but it bothers these people if they do. If they leak, the EPA [Environmental Protection Agency] gets the oil out of the water, digs the dirt up and puts it in hazardous waste, and brings in new dirt. It can cost thousands of dollars.”
Scott Powerline rented the crane to Georgia Power for wetlands work, and kept it for two years before selling it on, in October 2007, to Chico Irrigation, a company that maintains pumps for catfish farms. “It’s perfect for them – you don’t want oil getting in the water and killing the fish.” The company maintains a new fleet and sells on cranes more than a few years old.
Winn said that Scott Powerline has also used the vegetable oil in other cranes when the job spec calls for it. “Some powerline companies wouldn’t let cranes get on there with regular hydraulic oil.” The company has flushed and refilled other National cranes, digger derricks and Mantis telescopic crawlers (it is a dealer) with the oil. “We wouldn’t fill it all up, but enough to work every function. You won’t get every bit out, but enough that it won’t hurt if you blow a line. The Mantis cranes can blow 90 gallons a minute if you blow a line.” He admits that rather than fixing a minor leak on the 690EU boom truck, he just bought more oil to top up the hydraulics. “We figured that it wasn’t going to hurt anything.”
Winn took oil samples from the National ENVI 690EU crane for 18 months. He says that the oil, proprietary blend EL 3046 by manufacturer Terresolve, said that it worked just as well as mineral oil.
“We didn’t have to change any filters or hoses. It was completely compatible with all the components. In fact it is much better to work with and around and there is only a very mild smell. They tell you that it smells like french fries and while the biodiesel has a vegetable oil smell, it’s not so much with the EL 3046. The mechanics prefer working with the EL 3046 because they know it’s not toxic and if they get some on their hands it’s not an issue. I heard that some guys say it makes their hands softer, but they have never said it to me.”
The oil’s unique chemistry offers users two other benefits. Cranes running EL 3046 are a bit more responsive in the cold and maintains stability in the heat, says Mark Miller, CEO of Terresolve Technologies. The oil has a much higher viscosity index than mineral oil. VI is the fluid’s resistance to change as the temperature changes. The higher the VI, the more resistant a fluid’s viscosity (thickness) is to change and the broader the temperature range where equipment can work. Biodegradable fluids have a VI of about 200 as compared to petroleum fluids that are about 100. One measurement of the life expectancy of a hydraulic fluid is the Rotary Pressure Vessel Oxidation Test (RPVOT, formerly RBOT); also know at ASTM D-2272. The higher the number the more oxidative stability a fluid has and, as such, fluid life expectancy. Standard petroleum hydraulic fluids have a typical RPVOT of about 300 minutes; where as EL 3046 has a value of almost 400 minutes, a 30% increase.
Still, recommended service intervals are the same as mineral oil – every 5,000 hours. The final difference to mineral oil is the price. In mid-January, Scott Powerline was quoting a price of EL 3046 about five times that of plain AW 68, or about three times as much as Shell Telus 32 hydraulic fluid for colder areas.
“Readily biodegradable fluids just cost more”, says Miller. “They start with more expensive base fluids and utilize more expensive chemistry which will give the performance required without reducing the environmental benefits.” He adds: “There are a lot of people who market ‘inherently biodegradable’ products, but that means nothing, just that one day it will degrade. Everything is inherently biodegradable, even uranium. A readily biodegradable fluid such as EL 3046 will break down into safe natural components within 28 days measured by standard industry tests like the ASTM D 4684.”
