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After completing all of the surveying and paperwork, the first physical work done on a construction site usually involves clearing the land. When the land is heavily wooded, removal of trees, of course, is first and foremost. Large trees are generally harvested for their timber, but smaller ones are usually ground into mulch. Naturally, large mulchers depend on hydraulics to develop the high torque and high speed needed for these heavy-duty machines.
Designers of this equipment expect plenty of shock and vibration, which poses little threat to rugged hydraulic components and systems. What does lurk as a serious threat, however, is water. Water can enter a machine’s hydraulic system through worn seals and reservoir breathers. It can also condense on the inner walls of reservoirs due to dramatic temperature swings.
Potential problems of water in hydraulic oil are many. Water can break down an oil’s lubricating film, making sliding surfaces vulnerable to rapid wear from metal-to-metal contact. Water can react with the oil and alter its chemistry, rendering it less effective as a lubricant. In cold climates, water can collect and freeze, creating a whole new slate of problems.
Water Woes
Water contamination of hydraulic oil plagued a subcontractor using excavator-mounted tree mulchers in Western Canada. The equipment regularly operated on uneven terrain, was subjected to heavy shock and vibration, long duty cycles, dirty operating conditions, and wide swings of ambient temperatures. Each mulching attachment tapped into the oil reservoir of the excavator driving it. Depending on the excavator, reservoirs ranged in capacity from 66 to 80 gal (250 to 300 l), and all machines used ISO 46 hydraulic oil.
None of these hostile conditions posed a serious risk to productivity because, again, equipment designers had taken all of these conditions into account. Ingression of water, however, proved to be the Achilles heel of the hydraulic systems.
Repeated equipment malfunctions and premature component failures led the contractor to analyze the equipment’s hydraulic fluid. Analysis showed an unusually high concentration of water: 3,600 PPM (0.36 %) in an excavator after operating only 300 hr., so the hydraulic oil was drained and replaced with fresh oil. Conducting a particle count of the hydraulic oil showed an ISO 4406 cleanliness code of 22/21/16.
Problems persisted, and workers figured water and contamination had not been completely removed when the fluid was changed, so they changed it again. However, subsequent analysis indicated that water concentration in the oil still exceeded 1,100 ppm (0.11 %).
Dehydrator Dries Things Up
The contractor then decided to use a Triton-E Dehydrator Station from Schroeder Industries to remove water and particle contamination from the hydraulic oil, so that it fell within or below recommended concentrations. The Triton-E Dehydration Station removes particle contamination and all free water, as well as up to 90% of dissolved water from reservoirs sized to 1,000 gal with low water ingression rates or 400-gal reservoirs with high water ingression rates.
The Triton-E relies on mass transfer dewatering, where ambient air is filtered and dried to increase its water-holding ability. The dry air is then injected into a reaction chamber, where the hydraulic fluid cascades down through reticulated media and the clean-dry air stream. Water is transformed to vapor and expelled from the unit as a moist air stream.
The Triton-E was first connected to remove dirt and excessive water from the reservoir. Next, cylinders and motors were cycled to return contaminated fluid back to the reservoir so it, too, could be cleaned and dried. The dehydrator ran intermittently for 12 hr. to reduce water content to only 400 PPM (0.04 %), with an ISO 4406 final particle count of 20/15/11.
The time to repair, flush, and fill the first excavator required 60 to 70 man-hours at $178/hr. Adding in the cost to replace the oil and shop supplies, expenses came to $14,000.00. In contrast, the cost to rent the Triton-E ($2,300), including setup, and labor to monitor the 12-hr. operation, came to $4,430.00 — roughly one-third the cost. Not surprisingly, the Triton-E was used on the contractor’s four additional excavators.
For more information on the Triton-E Dewatering Station from Schroeder Industries, Leetsdale, Pa., call (724) 318-1100 or visit www.schroederindustries.com.
