Hydraulic Fluids: Contamination Is Not an Option
Is cleanliness next to godliness? When it comes to your hydraulic system you’d darn well better believe it!
Just about anybody with a piece of heavy equipment will tell you that hydraulic fluid is the lifeblood of a machine. In fact, comparing hydraulic fluid with blood is common among industry professionals, and the reason is clear: Roughly 80% of hydraulic failures are the result of fluid contamination.
It helps to think of contamination as an infection, which is little more than the introduction of foreign bodies into the bloodstream or other body parts. And like an infection, contamination will only get worse if it’s not treated. The most likely result: system failure and very expensive repairs.
Photo: John Deere
|John Deere's new Super Caddy is a filter cart that has a built-in particle counter that allows a technician to filter hydraulic oils to specific cleanliness levels. |
“If you get caught off guard by contaminated oil it can get really costly,” says Mike Daly, service marketing specialist with John Deere.
Luckily for heavy-equipment managers, technology—with diligence—is making the task of keeping hydraulic systems clean easier than ever. Filters, mobile filtration carts, and fluid analysis allow contractors to stay on top of maintenance, and to catch potential problems before they shut down a machine.
The role of high-tech products in hydraulic systems management mirrors the development of the industry. It might seem that at one time you could top off your reservoir with a garden-hose siphon and forget it, but those days are long gone. Today’s hydraulics operate with the unforgiving tolerances of nuclear reactors.
“We’re talking about filtering down to the levels of red and white blood cells,” says Al Zingaro, marketing manager of Parker Hannifin Corp.’s hydraulic filter division. “In fact, the ISO [International Organization for Standardization] code that is currently in use to measure acceptable particles for a given size is in particle ranges below that.”
|Mobile filtering is just one part of Caterpillar's approach to maintaining a machine's hydraulic system. |
Big Problem, Small Package
Some manufacturers call for filtering as low as 4 or 5 microns. Given that the smallest visible particles are about 40 microns, “What you can’t see can hurt you,” says Tom Blansett, product sales manager for the western region for Eaton Corp.’s hydraulics division.
To illustrate how small the particles being filtered are, Blansett, who got his start in hydraulics 28 years ago in submarines, notes that white blood cells are about 25 microns, while red blood cells are around 8 microns. If you ran your blood through a typical filter, he says, “You’d be very clean, but you’d be dead.”
A hydraulics system can fall victim to contamination from myriad sources: new oil, new components, ingression, and internal generation. In each, filtering is the key to preventing contamination, whether through the use of good filters or a mobile filtering system. We’ll take a look at these to see what owners and operators of heavy machinery can do to keep their hefty investments hydraulically healthy.
New Oil, Dirty Oil
Most people who work around hydraulics will tell you that preventing contamination begins with adding oil.
“New oil is basically dirty oil and it should be filtered before it’s put into a machine,” says Dan Schultz, directly marketed accounts manager for Schroeder Industries, a leading manufacturer of mobile filtration carts and filters for hydraulic systems.
Although the oil is refined to exacting standards, its transfer through various hoses to storage tanks and drums—all of which likely harbor unwanted particles—virtually ensures its contamination.
“In a lot of cases what is overlooked is when you add the fluid itself,” agrees Zingaro. “Most new fluid isn’t clean enough for the performance specifications of the fluid in working condition.”
The solution, Zingaro says, is the use of a mobile filtration cart, or transfer cart. Essentially dialysis machines on wheels—they’re also called kidney loops—these carts work on a simple principle: Take in new fluid from its drum, run it through a filter or two, then pump the cleaned oil into the reservoir. They can range from a simple single-filter unit to high-flow versions with multiple filters, onboard particle counters, and printers to provide readouts. “You can set it up so it will circulate the oil until it reaches an ISO cleanliness level,” Schultz says. “Once it reaches that level it will shut off and you can print out the data for the company’s records.”
A filter cart, used properly, makes maintenance sense and ultimately can save a contractor thousands of dollars. “The benefits of filtration are you preserve your oil, you don’t have to add as much, you don’t have to replace it, it lasts longer, and your performance is better,” Zingaro says.
Not every contractor needs his own cart, but it makes some monetary sense for those with several machines to have a basic filter cart. “The guy with five or six machines, he should have a filter cart just for topping off fluids,” Schultz says. “At minimum.”
Filtering new fluid is the most common use of transfer carts, but they also play a significant role in scheduled maintenance. Increasingly, say hydraulics professionals, dealers and contractors use filter carts to get a machine’s oil to a desired cleanliness level.
“A huge place for them is in dealers, where they’re bringing in the customer’s machine and servicing that machine,” Schultz says. “At large dealers they’re using the carts to check the ISO cleanliness level of the oils often. They run the filter carts on them to keep the contamination levels down. We’re seeing a lot more of that.”
John Deere, in fact, recently entered into the filtration cart market with its Super Caddy, which the company calls the most advanced unit on the market. “Super Caddy takes out particulates and free and emulsified water,” says Daly. “It also has a readout that tells you what cleanliness level you’re at, and what saturated moisture level you’re at.”
Daly says the chief customers of its Super Caddy are dealers who do maintenance. “The dealer can take this out to the field when they do PM,” says Daly. “It adds an element of visibility that in the past was strictly ritual.” That visibility, he says, is provided by the machine’s ability to count particulates in the oil. Such real-time feedback lets a user filter a system to a specific cleanliness level. The result: guesswork and hoping for the best are removed from routine hydraulic maintenance.
Beyond the addition of fresh oil, another crucial time to filter a machine’s oil is after new components are installed. Hoses in particular are notorious for harboring contaminants—slag, rubber, dust, etc.—simply as a result of the manufacturing process. In addition, taking a machine apart opens its hydraulics to contamination. Again, think infection. Good dealers strive to keep their shops clean, but dust and dirt are just facts of life. “When a dealer puts a system back together,” Daly says, “we use the Super Caddy to help us ensure that we’re setting the stage for a long and productive life. You don’t want to leave the contaminants behind.”
If contaminants are akin to infection, attachments can be a nasty source of trouble. Some machines, like scrapers, have huge oil volumes with long lines, and swapping attachments between them virtually guarantees the spread of contamination. Not all machines are created (or maintained) equal, says Daly, who warns that one “dog” in a contractor’s fleet can easily pass along its contamination through swapped attachments.
|Schroeder's Mobile Filtration System is ideal for cleaning up systems or prefiltering new oil. |
“A lot of times those systems are shared among different machines and they take the failure mode of one machine and pass it to the other guy,” Daly says. “Those are incidents with a machine that’s a dog that’s gotten itself in a situation where it brings in contamination and infects other machines. Fluid analysis and a caddy are a good way to measure that. The caddy can help you recover from that. In many cases the recovery from an incident is very effective, so you don’t have to pitch the oil and go through a whole cleanup on the machine.”
Filter carts won’t take the place of analysis done in a lab, but they can be a vital element in keeping your equipment in good shape. It’s what Daly calls “optimizing maintenance … the idea that the cart can help a contractor get the most of his maintenance budget by the smart use of tools and technology.” Carts will do the work, but determining when a piece of equipment needs service is the contractor’s job. And, say the experts, it’s more involved than simply following the manufacturer’s recommendations based on service hours. An original equipment manufacturer (OEM) might call for service at 500- or 1,000-hour intervals, but consider the conditions under which most equipment works. “They’re not operating in clean rooms,” Blansett says.
In machines that work in a “severe-duty environment,” Daly says, filtering on intervals as frequent as 250 hours might be desirable. “We don’t know how dirty the oil is,” he says. A cart with a particle counter, however, will tell you.
For contractors, filtering their equipment so frequently may seem excessive. If the OEM is fine with 1,000 hours, why mess with the schedule? “What might seem like an extra step or cost might save you money,” says Daly, who likens regular filtering to monitoring your health. For example, statistics show that quitting smoking can add more than a dozen years to your life. The caveat is that you have to do it while it’s physiologically meaningful. “You don’t go to your 64th birthday to decide to quit smoking to add 13 years to your life,” he says. So it is with your machine’s hydraulics.
Photo: John Deere
Photo: John Deere
|Dialysis for the massive.|
Regardless of the machine used, you can’t keep a hydraulic system clean if you don’t use good filters and change them regularly. “A lot of customers might already have filter carts, but you want to make sure you put a good-quality element in the cart,” says Schultz. By that he means “a small-micron element—high efficiency, high dirt-holding capacity. You want to get the most bang for your buck.”
Filter makers do a balancing act when designing elements, as Parker Hannifin’s Zingaro explains. “I think the important thing for us is designing a filter so there’s value,” he says. “It provides the very important efficiencies of contamination control, but also it has the capacity to give reasonable life for the customer. You could put a brick in there and make it fit, and if it stopped everything that’s good. But then of course there’d be no flow. What you really need is an optimum situation where you get very good efficiency so that you have at least 99%-plus for particle removal … and yet you also have very high capacity.”
When Zingaro talks about value, he doesn’t mean “cheap.” Yes, you can probably save some money by ordering inexpensive elements, but remember that you get what you pay for. And don’t forget how much you paid for your heavy equipment.
“When you replace your elements, you want to ensure you use a quality element. You’ve got an expensive system here. You can buy elements … from anywhere.” The problem, Zingaro says, is that “they’re not all qualified. What you have are what we call ‘will-fitters,’ so it’s tempting sometimes to buy the least costly element.”
Even the best filters have a limited lifespan. Change them according to the OEM’s recommendations, say the experts, or more often if you’re working in particularly dirty conditions. Letting them go too long renders them useless at best, harmful at worst. Rudy Urbano, senior marketing consultant, hydraulic parts products, for Caterpillar, notes that filters are designed with a bypass that allows oil to flow through the element even if they become clogged with particles. The problem, he says, is that as the fluid hits the clogged filter and flows through the bypass, “It’ll begin to pull contamination back out of the filter and into the system.”
Keeping It Clean
Filter carts and filters are just two of the factors in keeping hydraulic systems clean and running at peak efficiency. Most manufacturers of equipment and filtration products tend to take a comprehensive approach to controlling contamination. Some, like Eaton, advocate a “systemic” approach to oil cleanliness that targets every aspect of a machine’s hydraulics. Caterpillar offers its Custom Hydraulic Service, a series of inspections, analyses, and solutions for heavy equipment.
Eaton’s Blansett calls hydraulics “a highly technical area in a field that’s seen as grunt-level.” Big machines moving large things in the dirt might not seem like the stuff of science, but a hydraulic system is indeed a complex chunk of machinery. Taking care of its oil will simplify your life on the job site.
Author's Bio: Jim Logan is the staff writer for Forester Communications.