"Hydraulics operate at very high pressure (3,000 to 6,000 psig). Contaminants or dirt can be detrimental at these pressures if they are not properly filtered," says Naman. "They behave like sandpaper, which is very abrasive and can cause premature wear."
Even microscopic-size particles can produce negative effects, such as "three-body abrasion". "Three-body abrasion is when you have two surfaces, then introduce a hard, clearance-size particulate that scrapes or abraids the metal surfaces and actually starts to wear away metal," Badal explains. "Basically, you start a chain reaction. Once it starts to wear, you get more particulates and they cause more wear. You start a cycle if you don't filter it or correct the problem."
A fluid transfer cart - or filter cart/caddy - can remove microscopic particles, as well as water, from the fluid. "It moves the fluid across a 2-micron filter to take the majority of contamination or any water content out as you're transferring it from, say, a 55-gallon drum on the back of a lube truck," Urbano explains.
A filter cart can also remove contaminants already present in the hydraulic system. "Instead of draining and replacing contaminated hydraulic oil, it can continue to be used as long as the zinc content remains above 900 ppm," says Urbano. "The payback is getting twice the life out of your oil."
Filter carts can range from a couple thousand dollars up to $10,000 or more, depending on the size (gpm/lpm rating) and features. Yet, this is one tool where there is little question about ROI.
"From the financial point of view, a filter caddy can achieve two goals: extending the life of the fluid and extending the life of components," says Navarro.
Oxidation occurs due to the presence of water, solid particles and temperature extremes, he continues. Keeping the fluid clean can reduce the potential for oxidation and an increase in the TAN (Total Acid Number). This, in turn, facilitates extended service life.
"A big machine with a 100-gallon tank could represent $600 in materials," says Navarro. Add filters and labor, and it's roughly $1,000 every time you change fluids. "If you multiply that by the number of units in your fleet, and you can extend the life of the fluid 25 or 30 percent, that money accumulates."
Of course, the real payback is in reduced component wear. "If you use a caddy to keep fluid clean, and you prevent a hydraulic pump from failing, it can give you savings to buy several filter caddies," Navarro states.
In Urbano's opinion, using a filter cart is really just a matter of following proper maintenance procedures. "Intuitively, you know that cleaner hydraulic oil is going to give you less wear and tear on that hydraulic system," he comments, whereas, unfiltered oil can cause thousands of dollars worth of damage. "Say that you put unfiltered oil in a machine and it causes a pump to fail. A high-dollar piston pump can be $10,000 on one machine."
Filter carts are a necessary tool to help prevent such failures. "We don't really recognize this as an ROI piece of equipment," says Urbano. "It's just a mandatory way of doing the proper oil transfer."