Abstract: The method consists of passing the substance to be analyzed through a measuring circuit at a constant flow rate, the temperature therein being maintained at a value sufficiently below the assumed crystallization point of the substance. Heating means are provided along the flow path of the liquid substance in said circuit. The substance in the course of cooling is kept in contact with an isomorphous crystalline material. The heating means is automatically turned on and off respectively at two characteristic temperatures, which are detected by measuring the pressure drop or difference of pressure of the substance at the inlet and at the outlet of the measuring circuit, variations of the pressure drop being effected as a function of temperature.

Abstract: A method and apparatus for the continuous automatic measuring of the filterability threshold temperature of a liquid such as a doped diesel oil comprising passing the doped diesel oil through a measuring circuit surrounded by a cooling liquid at a constant flow rate, providing a crystal retaining means beyond the cooled part of said measuring circuit, measuring the pressure differential before and immediately after said crystal retaining means, and providing resistance heating to said measuring circuit when the measured pressure differential exceeds a predetermined value and continuously measuring the temperature of said liquid immediately down stream of said crystal retaining means. The switch of the device is actuated in response to the pressure differential increasing beyond a predetermined level which is caused by a build-up of microcrystals, for turning on the resistance heating circuit and melting the microcrystals.

Abstract: A method and apparatus for the continuous automatic analysis of the filterability point of liquid substances such as Diesel oil. The Diesel oil flows through a measuring circuit at a constant flow rate by means of a volumetric pump. The temperature in the measuring circuit is maintained sufficiently below the assumed filterability point of the substance. A heating element is provided along the flow path of the Diesel oil for melting microcrystals which form on the filter in the filtering chamber of the measuring circuit, or alternatively, in a tube of the measuring circuit. A differential pressure responsive device with a switch is connected between the inlet and outlet of the measuring circuit for detecting the pressure drop across the circuit. The switch of the device is actuated in response to the pressure drop falling below a predetermined level which is caused by a build-up of micro-crystals, for turning on the heating element and melting the micro-crystals.