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Most of those involved in hydraulics apply cleanliness strategies to improve machine reliability and longevity, and for years, one given is to maintain clean fluid in the reservoir. Typically, the first step was to apply filter-breathers—to keep larger particles of dirt out of the reservoir as fluid level rises and falls. The next step incorporated desiccant-filter-breathers to exclude contaminants and moisture.
However, filter-breathers generally do not stop small particles from entering, so they must be checked and replaced periodically as the filter elements reach their dirt-holding capacity. Likewise, desiccant breathers must be checked and replaced when they become saturated with water.
The ultimate in contaminant and moisture exclusion is an environmentally sealed reservoir, which provides a physical barrier to separate air in the reservoir from the ambient environment. Military and other aircraft often use sealed hydraulic reservoirs, but their cost and complexity generally make them impractical for most industrial and mobile hydraulic systems.
Mechanical engineer John A. Paoluccio, P.E., offers a solution to this dilemma with his OilN2 device. The OilN2 is the latest product developed by Inventive Resources Inc., a family business founded in 1984. OilN2 uses a bladder to physically isolate the air in a hydraulic system’s reservoir from ambient conditions. It also uses a thermal conduction rod to attract and capture oxygen and moisture already in the reservoir into a replaceable cartridge. The result is clean, dry air in the reservoir that’s essentially depleted of oxygen, which hinders corrosion and oxidation of fluid.
How the Device Works
Paoluccio explains that dirt and moisture in the ambient air is not an issue, because a bladder physically prevents the hydraulic system from ever being exposed to ambient air again. The bladder expands and contracts with changes in hydraulic fluid level. Thus, once the OILN2 is either connected to the breather vent port or remotely mounted, the user only has to deal with the air already in the reservoir. The existing air in the reservoir typically contains airborne dirt, moisture, and, of course, oxygen.
The OilN2 alters the interior environment of the reservoir to a clean, dry nitrogen state. Oxygen and moisture molecules in the internal air are attracted and captured by a combination thermal conduction rod and cartridge with oxygen absorber and desiccant dryer media. The attracted oxygen molecules undergo a chemical reaction that locks them in the cartridge. This depletes the oxygen in the air, leaving a high concentration of nitrogen. The easily replaceable cartridge may last for years on a tight system.
A cool spot is formed on the thermal conduction rod, causing condensation of oxygen and moisture. This works continuously, even when the hydraulic system itself is idle. However, the thermal conduction rod is more aggressive when equipment turns off and cools after each operating cycle. When the system operates and heats the oil, water molecules are driven from the oil and enter the air chamber. Paoluccio says that, depending on the system, return on investment can occur in only a few months.