Method of manufacturing bio-diesel and reactor

A reactor comprising:

• a substantially fluid tight tank comprising an interior and an exterior;
• a heat transfer media positioned within said tank;
• a plurality of reaction lines positioned within said tank, wherein said plurality of reaction lines are in thermal communication with said heat transfer media and wherein said plurality of reaction lines are in fluid communication with one another and with said exterior of said tank;
• a manifold configured to regulate fluid communication between said plurality of reaction lines, wherein said manifold is configured to selectively allow fluid exiting a first of said plurality of reaction lines to flow to a second of said plurality of reaction lines or to divert fluid exiting said first of said plurality of reaction lines away from said second of said plurality of reaction lines;
• wherein said manifold is provided with at least one sensor configured to measure a mass flow rate of fluid flowing through said reactor, said fluid having a density, and wherein said manifold is configured to divert fluid exiting said first of said plurality of reaction lines away from said second of said plurality of reaction lines if the density of the fluid has fallen by at least about 1 pound per cubic foot;
• at least one heater in thermal communication with said heat transfer media;
• and
• at least one means for pumping said reactant fluids through at least one of said plurality of reaction lines.