I was recently asked about the process of flushing Automotive Lift Repair Tampa Florida hydraulic systems when switching from one type of fluid to another. Some suggestions included using brake cleaner, diesel fuel, or acidic cleaning agents.
However, brake cleaner contains chemicals like acetone and tetrachloroethylene, which can damage seals made from materials such as nitrile, neoprene, polyurethane, and silicone. Ethylene-propylene (EPDM) seals, which are particularly vulnerable to petroleum oils and solvents, are not recommended for exposure to aromatic hydrocarbons or diesel oil.
Depending on the types of O-rings and seals in your hydraulic system, using solvents like brake cleaner or diesel fuel may dry out or damage these components. Additionally, it’s important to consider compatibility with the new fluid being introduced.
For these reasons, it’s crucial to understand proper flushing techniques or enlist the help of an experienced oil flushing service to ensure the job is done correctly.
Tom Odden’s article “Cleaning and Flushing Basics for Hydraulic Systems and Similar Machines” offers a comprehensive guide to thoroughly cleaning a hydraulic system. This method involves both mechanical and chemical cleaning of the components and the system, making it a reliable “one-size-fits-all” solution.
A recent poll revealed that Automotive Lift Repair Tampa Florida lubrication professionals prefer mechanical cleaning as the most common flushing method used at their plants. While not everyone will conduct a full teardown and thorough cleaning for each fluid change, it’s essential to at least follow some basic steps when cleaning a hydraulic system.
Minimum Steps for Cleaning a Hydraulic System:
Step 1:
While the fluid is warm, drain the system completely, including the reservoir, lines, cylinders, accumulators, and filter housings. Replace the filters.
Step 2:
Use a lint-free rag to clean the reservoir of any sludge or deposits, ensuring no soft or loosened paint remains.
Step 3:
Flush the Automotive Lift Repair Tampa Florida system with a lower-viscosity fluid similar to the one being introduced. Achieve a Reynolds number of 2,000 to 4,000 to create turbulence that removes particles. Frequently stroke valves to flush them thoroughly. Continue flushing until the system reaches one level cleaner than the target cleanliness level.
Step 4:
Drain the flushing fluid while it’s still hot. Replace filters and inspect the reservoir again.
Step 5:
Fill the system to 75% with the new fluid. Bleed the pump and open any pressure reliefs or bypasses. Run the pump briefly, repeating to prime it.
Step 6:
Run the pump for a minute with the bypass open, then close it and allow the pump to operate for five minutes. Do not run the actuators yet.
Step 7:
Operate the actuators one at a time, letting fluid return to the reservoir before moving on. Monitor the fluid level, adding more if necessary.
Step 8:
Refill the Automotive Lift Repair Tampa Florida reservoir to 75%, run the system in intervals, and bleed the air at each shutdown. Listen for signs of cavitation.
Step 9:
Run the system for 30 minutes, then shut it down and replace the filters. Inspect for cross-contamination.
Step 10:
After six hours of operation, replace the filters and test the fluid.
Step 11:
Increase the frequency of sampling until you are sure the fluid is stable.
Flushing Tactics:
Various methods can be used to flush a hydraulic system, each suited to different conditions:
– Drawdown Filtration/Separation: Removes contaminants via filtration.
– High Turbulence, High Fluid Velocity, Low Oil Viscosity: Specialized equipment increases turbulence for effective flushing.
– High Flush Oil Temperature: Increases turbulence and oil solvency.
– Cycling Flush Oil Temperature: Uses heat exchangers to dislodge deposits.
– Pulsating Flush Oil Flow: Changing flow rates helps clear contaminants.
– Pneumatic Vibrators and Hammers: Break debris from pipe walls.
– Sparge Flush: Air or nitrogen bubbles improve cleaning.
– Reverse Flush Oil Flow: Changing flow direction dislodges deposits.
– Wand Flush Tool: Directs high-velocity oil flow in accessible areas.
– Charged Particle Separators: Removes varnish and contaminants.
– Solvent/Detergent Flush Fluid: Involves mineral spirits, diesel fuel, or motor oils.
– Chemical Cleaning: Uses caustic agents to remove organic sludge.
– Mechanical Cleaning: Employs scrapers and abrasives to remove hard deposits.
Selecting the right flushing tactic depends on the specific issues in the system. A fluid changeover is not just a simple drain-and-fill; it requires careful attention to ensure the system is thoroughly cleaned before introducing the new fluid.
Over the past two decades in the hydraulics industry, I’ve had the opportunity to observe and learn from the common mistakes and oversights that users make when maintaining their equipment.
Mistake No. 1 – Changing the oil
There are only two reasons to change Automotive Lift Repair Tampa Florida hydraulic oil: when the base oil degrades or when the additive package is depleted. Since many factors affect how quickly these occur, changing oil based on service hours without checking its actual condition is like guessing. With the high cost of oil, wasting good oil is costly, while running on degraded oil can shorten the lifespan of your entire hydraulic system. The only reliable way to know when an oil change is necessary is through oil analysis.
Mistake No. 2 – Changing the filters
Changing filters based on a schedule can also lead to problems. If you change them too early, you waste money; if too late, particles bypass the filter and cause wear on system components. The ideal time to replace filters is when they’ve reached their full dirt-holding capacity but before the bypass valve opens. This requires monitoring the pressure drop across the filter and acting when needed, either with a clogging indicator or continuous pressure drop monitoring.
Mistake No. 3 – Running too hot
While most Automotive Lift Repair Tampa Florida equipment operators wouldn’t allow an engine to overheat, many overlook excessive heat in hydraulic systems. High temperatures are one of the quickest ways to damage components, seals, hoses, and the oil itself. Hydraulic systems are running too hot when oil viscosity drops below the level required for adequate lubrication, which varies based on oil type and system components. Running above 82°C can also harm seals and accelerate oil degradation.
Mistake No. 4 – Using the wrong oil
Automotive Lift Repair Tampa Florida Hydraulic oil serves both as a lubricant and the medium for power transmission, making its viscosity the most critical factor.
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