Reports from fluid labs may look like this, showing users where their samples rated for different sized particles, as well as for water contamination and viscosity. Chart courtesy Eaton Corp.
viscosity (ASTM D445) — measures fluid flow rate. Too high or too low a viscosity may lead to fluid breakdown, inefficient equipment operation, premature system failure, or damage to other components.
water (ASTM E203) — determines water content in a fluid. Excess water reduces the viscosity of hydraulic fluid, which can increase the likelihood of adverse chemical reactions and degrade equipment performance.
Drawdown Particle Isolation — detects insoluble contaminants in fluids, including insoluble particles and organic or inorganic gel-like matter.
Automatic Particle Count (ISO 11500) — counts the number and size of particles in a fluid sample and then defines contaminants according to size distribution and quantities. Results indicate any needed corrective actions.
Spectrometric Analysis (ASTM D 5185) — evaluates the condition of additives in a fluid, as well as wear metal content.
Energy Dispersive X-ray Fluorescence (ASTM E 1508) — pinpoints contaminant types, which aids in identifying origins.
pH (ASTM E 70) — determines the acidity or alkalinity of watercontaining hydraulic fluids.
Total Acid Number (ASTM D 974) — measures the amount of acid and acid-acting material constituents in a fluid. An increase in TAN indicates oxidation or acid contamination.
Once testing is complete, users are provided with the findings, which may include photos of the contaminants and tips on how to improve or maintain current fluid conditions. Conducting trend analysis, by comparing data from two previous samples, with current results, may also be meaningful.
Interpreting findings
Some common problems found in fluid samples are:
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elevated water content — due to ingression into the reservoir during equipment servicing or fluid refilling
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elevated particle count — due to inefficient filtration of particles, such as oxidized metal from fill fluid or system piping, steel from valve or pump wear, silica or fiber from external ingression or process operation, and
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oxidation — due to high system temperatures causing a reaction between the oil and oxygen, which can form sludge in the oil, lacquers, and varnishes on hot surfaces.
Some labs will provide an analysis report within 24 hours of fluid sample receipt. The report includes tips on improving or maintaining current fluid conditions and compares data from two previous samples, if available, with results of current samples. Viewing results of three side-by-side samples aids in easy recognition of trends that may indicate increased levels of contamination.
Labs also may offer guidance on what to do about contamination. Based on the type of metal content found in a fluid, they could recommend that users check on specific system components that may be wearing out and releasing particles into the fluid.
Selecting a lab
Because many fluid analysis labs are available, be sure to
look for one with experience, a full range of testing capabilities, ISO certification, and quick turnaround time. The most reliable labs will provide the best fluid evaluation — and the best means to improve and maintain the health of your hydraulic fluid.
Wassan Shaffou is lab manager for Eaton Corp., Southfield Mich. Visit hydraulics.eaton.com/services/ fluid_analysis for more details on Eaton's lab.
