Measuring fluid properties to detect oil contamination, degradation

Diesel Progress North American Edition, April, 2009

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The new multiparametric Fluid Property Sensor (FPS) by Measurement Specialties is designed to directly and simultaneously measure viscosity, density, dielectric constant and temperature of fluids. The French manufacturer explained that the new unit can detect contaminants and profile the degradation of oils and lubricants and even determine fuel quality for optimizing engine operation.

The FPS is suitable for a wide range of OEM and aftermarket applications including on- and off-highway vehicles, compressors, turbines and industrial equipment.

Measurement Specialties said that the strength of the new FPS lies in its multiparameter measurement capability. Unlike single-parameter sensors such as conductivity sensors or acoustic viscosity sensors that only measure one physical property, the FPS measures three important physical properties of fluids to determine the condition and quality of the fluid.

Contaminants like soot, water, ethylene glycol coolant and fuel in engine oil are easily detected because each uniquely changes one or more of the physical properties measured by the FPS. Oil oxidation also impacts the physical properties measured by the FPS, the company said.

In practice, the FPS works like an onboard laboratory where multiple analytical tests are carried out to measure the physical properties of fluids. The quality of properties measured by FPS is comparable to the same values measured by standard analytical laboratory instruments, the company said.

The FPS utilizes tuning fork mechanical resonator technology that simultaneously and directly measures viscosity, density and dielectric constant of fluids. Fluid temperature is measured by a resistance temperature detector, which is incorporated into the FPS assembly along with the tuning fork sensor element.

The sensor can be installed into high-pressure, high-flow conduits or process streams as well as fluid reservoirs. The sensor's measurement accuracy and precision are not affected by static or changing fluid flows or pressure, the company said.

The manufacturer maintained that the sensing element has effectively monitored fluids in a broad application range including pressures exceeding 5000 psi, temperatures ranging from -76[degrees] to 300[degrees]F and vibration extremes up to 46 G.

Measurement Specialties also reported that these sensors have been successfully tested during thousands of operating hours on hydraulic fluid, gear oil, on- and off-road commercial vehicle engine operation and a diverse range of industrial applications.

The sensor is resistant to contamination and corrosive degradation from materials such as particles, fuel, ethylene glycol, metals, acids and bases. It is utilized in engine operation but can be used even in less complex environments, such as transmissions, gearboxes and hydraulic systems.

Finally, the FPS is a valuable tool for the detection of contamination, but at the same time monitors oil degradation to support condition-based oil drain intervals, the company said. It can allow the safe extension of oil drain intervals and permits operators to schedule oil changes according to a condition-based maintenance program.