Apparatus and method for determining the thermal stability of fluids

An apparatus for testing thermal oxidation stability of a test sample such as a hydrocarbon fuel comprising:

• a source of electric power;
• an intelligent heater tube connected to said source of electric power for flowing current to heat a center section of said intelligent heater tube to a predetermined temperature;
• a coolant flow circuit supplying coolant to each end of said intelligent heater tube to keep each end thereof near room temperature;
• an aeration circuit with an aeration pump for pumping air to aerate said test simple in a sample container;
• a test sample flow circuit for flowing said test sample around said center section to heat said test sample to said predetermined temperature,
• said test sample flow circuit including:
• a sample drive pump pumping said test sample from said sample container around said center section of said intelligent heater tube;
• a differential pressure filter in said test sample flow circuit after said intelligent heater tube to filter out any solids that may have formed in said test sample when heated to said predetermined temperature due to oxidation of said test sample;
• a differential pressure sensor for measuring differential pressure across said differential pressure filter;
• a back pressure regulator for maintaining said test sample being pumped by said sample drive pump at a test pressure high enough to keep said test sample in a liquid phase when heated to said predetermined temperature;
• a waste container for collecting said test sample after said test;
• a memory device on said intelligent heater tube for first recording of said differential pressure therein.