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	SwRI technician using radioactive tracer techniques to make highly accurate and sensitive real-time oil consumption measurements in operating engines.

The ability of radioactive tracer technology to measure near real-time oil consumption during engine operation provides a valuable tool for evaluating overall engine performance with respect to hardware designs, combustion technologies, engine operating strategies, and lubricant chemistries. Southwest Research Institute (SwRI) uses radioactive tracer techniques to make highly accurate and sensitive real-time oil consumption measurements in operating engines.

Benefits of the Radioactive Tracer Oil Consumption Method

The benefits of the radioactive tracer oil consumption method, which measures oil concentration in the exhaust, includes:

• Reliable data for measurements taken over short periods of time.

• Reduced cost

• Shorter development time because parameters are investigated quickly and accurately

The radioactive tracer oil consumption method is important because oil consumption has been identified as a strong contributor to diesel engine particulate emissions, which complicates the NO_x-particulate tradeoff. The tie-in of oil consumption to engine wear is also significant because increases ring and liner wear almost always leads to increased oil consumption.

Oil Consumption Testing Procedures

The oil consumption measurement is based on tritiation of the oil, followed by the measurement of radioactivity levels in continuous samples collected from the exhaust.

Tritiation is the process of replacing some of the hydrogen atoms in the oil with radioactive tritium (3H) atoms through catalytic exchange. This exchange takes place in a sample of base stock, which is then mixed with the fully formulated oil prior to testing. If all hydrocarbon in the consumed lube oil is burned to completion, all hydrogen—including the tritium—will be converted to water. Consequently, activity of the water collected in the exhaust sample will be directly proportional to the mass of oil consumed in the engine during the sampling period.

During testing, a continuous exhaust sample is taken at each engine operating condition. The sample is processed to obtain the total amount of water available. The radioactivity of this water is directly related to the mass of lubricant consumed during the sampling period, and it is calculated mathematically from the data.

For more information about real-time oil consumption measurement using radioactive tracer technology capabilities at SwRI or how you can contract with SwRI, please contact  Martin B. Treuhaft at mtreuhaft@swri.org or (210) 522-2626.

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Southwest Research Institute^® (SwRI^®), headquartered in San Antonio, Texas, is a multidisciplinary, independent, nonprofit, applied engineering and physical sciences research and development organization with 12 technical divisions.

April 28, 2009