Oil Coking - How to Monitor

Lindsay Potter, Noria Corporation

Tribology is the science and technology of friction, lubrication and wear; or of interacting surfaces in relative motion. Generally, any product where a material slides or rubs over another is going to be affected by either lubricated or unlubricated tribological interactions.1 The interactions of solid surfaces may result in a loss of surface material, more commonly known as wear.

Imperial Scientific Industries performs tribology and petroleum testing. Tribotesters, a subdivision of Imperial Scientific Industries, offers a complete range of tribology test equipment and services for friction, wear, lubrication and abrasion studies. A specific testing device developed by the company is the panel coking apparatus. Fluid coking is a process by which heavy residual crude is converted into lighter products such as naphtha, kerosene, heating oil and hydrocarbon gases.

The Design

Tribotesters' panel coking apparatus was designed to determine the tendencies of finished oils from coke when in contact with surfaces at elevated temperatures. Performing to Federal Test Method standard 791, the unit is supplied with PID temperature-indicating controllers for regulating the temperature of the test panel oil in the sump and air. It is also equipped with a variable drive motor, digital speed display and air flow regulator system.




The panel coking apparatus offers many features and variables such as the following:

  • Speed - Ten turn variable speed control pot. Ranges from 100 to 2,500 rpm

  • Temperature - Three heating system

  • Panel - 540°C (1,000°F) maximum

  • Sump - 300°C (572°F) maximum

  • Air - 40°C (104°F) maximum

  • Atmosphere - Variable air flow or other inert gases from 0.2 to 1.0 liters per minute is standard.

  • Timing System - Timer with automatic shutdown


Additional packages are available with the apparatus. An optional cyclic timing system allows for alternate splash/bake cycles to allow oil to bake for a period of time on the hot panel without the addition of fresh lubricants. A second optional system, the sulfur dioxide gas system, uses a sealed chamber and S02 delivery system to introduce and monitor a corrosive acidic atmosphere, which increases the severity of the evaluation.

Because of the versatility of this test machine to simulate different test conditions, it provides an economical method of evaluating coking tendencies of lubricants prior to performing expensive engine deposit tests. 



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