Some common problems found in fluid samples are:

  • elevated water content — due to ingression into the reservoir during equipment servicing or fluid refilling
  • 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
  • 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 fluid_analysis for more details on Eaton's lab.

Water and temperature sensor continuously monitors hydraulic and lubrication fluids
The new Testmate Water Sensor (TWS-C) from Schroeder Industries, Leetsdale, Pa., is designed for continuous monitoring of hydraulic and

lubrication fluids. The TWS-C measures water content relative to the percent saturation of the fluid, and ranges from zero (indicating the absence of water) to 100 (indicating 100% water). It is suitable for a variety of applications, including laboratory equipment.

A special capacitance sensor absorbs water molecules from the fluid and changes the capacity value that is directly related to the saturation level of the fluid. An integrated thermoelement on the sensor measures the temperature of the fluid in the range of 13° to 212° F ( 25° to 100°C). Both this value and the degree of saturation are reported as a 4 to 20 mA signal.

The TWS-C can be directly installed into the hydraulic system with a threaded connection. It is recommended that the sensor be mounted vertically in a known turbulent area with the mechanical connection pointing upwards in hydraulic applications. Additionally, the sensor should be fully submerged with fluid free-flowing around the sensor.

For more information, visit