Abstract: A method and apparatus for measuring the heating power of a combustible gas. The ratio of the temperature of gases entering and exiting a calorimeter is maintained substantially equal to 1, and the entering air is maintained at its water saturation limit. The calorimeter comprises two concentric cells having a central chimney closed at the top and housing a burner. A coiled tube discharges gases from the chimney. Two temperature probes transmit signals to a microprocessor which actuates a heat exchanger provided in an external wall of the outermost concentric cell.

Abstract: The level of the interfacial boundary between two liquids having different dielectric constants is located by means of a detector in which two parallel sectional members constitute external capacitor plates supported by a metallic base plate and in which small metallic plates encased within an electrically insulated central upright member constitute central capacitor plates. The assembly thus forms a plurality of capacitors, the plates of which are immersed in at least one of the liquids. Each capacitor forms part of an oscillating circuit connected to electronic means for effecting a comparison between the oscillation frequency and a reference frequency.

Abstract: The instrument comprises a viscometer for a product such as bitumen and a pump for transferring the product to a flat wall-type heat exchanger. A channel formed in the heat exchanger wall is brought to an adjustable temperature and the channel output is connected to the viscometer. A probe for measuring the temperature of the product is placed within the viscometer, the temperature being adjusted to an index value within a predetermined range by means of a regulator for varying the pump output and controlling the temperature of the heat-exchanger wall.