Abstract: A method of determining populations of live, whole bacteria electrochemically. The bacteria are filtered, and the filtrate is employed in association with an electrochemical measuring unit to determine the bacteria density. In accordance with a flow-through method, the average signal over the predetermined time period of the test is employed, in conjunction with a constant, to determine the population. In accordance with the bypass method, reagent is passed through a bypass line to the electrochemical measuring unit, and the resulting signal is subtracted from the signal resulting from the filtrate, a constant being employed to correlate the resulting remainder with bacteria count. A changing-concentration method employs a changing concentration of bacteria in the same fluid to determine populations of bacteria. A saved-sample method employs a second test of the same filtrate, after a predetermined time period, to compensate for any contaminants that may be present.

Abstract: A peristaltic pumping and metering apparatus and method whereby tube walls are squeezed inwardly against cores contained in the tubes. A plurality of rings are frictionally driven in epicyclic manner, to thus deform a contoured belt against the core-containing tubes.

Abstract: A thermal bridge is employed to compare thermal transfer characteristics of test and reference surfaces immersed in identical fluid environments so as to determine thermal transfer characteristics of the test surface substantially independent of fluid environment. The thermal bridge is balanced, the test surface is caused to be scaled to a greater degree than the reference surface and a comparative measurement is made with the two surfaces exposed to identical fluid environments. The method is performed by a single probe having two or more surfaces that are heated and of which the differential temperatures are monitored. Readings are adjusted to compensate for effects of a varying fluid environment.

Abstract: The method comprises employing electrical contact resistance to sense whether or not there is incipient precipitation of adherent scale, paraffin wax, etc., on surfaces immersed in various liquids. The method is surprisingly sensitive, and otherwise effective, even when the liquids are electrically conductive. The method further comprises performing certain steps relative to the submerged surfaces, and/or relative to the liquids, in order to control precipitate formation. The selection of polarity, materials, etc., is caused to be such that sensitivity is maximized, and electrolytic dissolution of the submerged elements is minimized.