Abstract: A method using a gas reservoir and a critical nozzle for determining physical properties and/or quantities relevant to combustion of gas or gas mixtures, the method includes: flowing a gas or gas mixture under pressure from the gas reservoir through the critical nozzle; measuring pressure drop in the gas reservoir as a function of time; determining a gas property factor (?*), dependent on physical properties of the gas or gas mixture, based on the measured values of the pressure drop; and determining a desired physical property or quantity relevant to combustion based on the gas property factor (?*) through correlation.

Abstract: A method to determine a physical property or a quantity of gas related to combustion including: flowing a gas from a reservoir through a critical nozzle and past a microthermal sensor wherein the mass flow of the gas through the critical nozzle is the same as the mass flow through the microthermal sensor; measuring the pressure drop in the reservoir as a function of time; deriving a first gas property factor based on a time constant of the pressure drop; determining a second gas property factor which depends from a flow signal generated by the microthermal sensor; determining a thermal conductivity of the gas; and determining the physical property or quantity based on a correlation between the physical property or quantity, and the first and/or second gas property factors and the thermal conductivity.

Abstract: A method and a measuring apparatus for determining specific quantities for the gas quality in which the gas or gas mixture flows through an ultrasonic flow sensor as well as through a microthermal sensor, and the former is used for determining the sound and flow velocity and the latter for determining the thermal conductivity and the thermal capacity of the gas or gas mixture. The sound velocity, the thermal conductivity and the thermal capacity are subsequently used for the correlation of the specific quantities for the gas quality.

Abstract: A method for determining physical properties of combustion including: flowing a gas a critical nozzle and past a microthermal sensor wherein the mass flow of the gas through the critical nozzle is the same as the mass flow through the microthermal sensor; measuring the pressure drop in a reservoir of gas flowing to the nozzle; determining a first gas property factor based on the measured pressure drop; determining a second gas property factor based on a flow signal generated by the microthermal sensor; determining a thermal conductivity of the gas using the microthermal sensor; and determining a physical property of the combustion based on a correlation of the first and/or second gas property factors and the thermal conductivity.

Abstract: A method for correcting offset drift effects of a thermal measurement device (10) which comprises at least one temperature sensor (15a, 15b) arranged at a defined distance from a heating device (12) for a fluid to be measured, for measuring at least one measurement variable describing the temperature and/or temperature profile during operation of the heating device (12), in which a reference measured value (35) is measured at a reference time in a first measurement of the measurement variable with the heating device (12) turned off, in which a drift measured value (36) is measured at at least one later time in a second measurement of the measurement variable with the heating device (12) turned off, and in which a drift correction is carried out during the measurement by using the heating device (12) on the basis of a difference between the drift measured value (36) and the reference measured value (35).

Abstract: The invention relates to a process and a device for thermal measuring the flow rate (v) of a fluid (3). In conventional thermal sensors the heating power P is supplied in the form of rectangular pulses. According to the invention, the sensor means (1b) are supplied by a heating control (2b) with non-constant heating pulses having a sublinear build-up dynamics P(t). Thereby, a nonlinear behaviour of the threshold value time (tS), until a threshold value temperature (Tm) is reached, as a function of the flow rate (v) can at least partially be compensated. Embodiments concern inter alia a build-up dynamics P(t) proportional to tm and/or to a time-independent amplitude factor (1+RS/RI)?1, wherein m is a Reynolds-number-dependent exponent and RS, RI are thermal transfer resistances. The advantages are an improved precision, a shorter measuring time and an enlarged measuring range for the flow rate v.

Abstract: A gas meter for determining a gas mixture consumption is revealed which determines sensor signal values proportional to a flow rate, this gas meter being calibrated as an energy measuring unit. The calibration is based on a basic gas mixture. During the measurement of the gas consumption, a measured energy consumption value is multiplied by a correction factor which takes account, at least approximately, of the calorific value of a supplied gas mixture, this calorific value being determined by an external unit. By this means, it is possible, using a simple and cost-efficient gas meter, to determine the effective supplied energy and to bill costs according to the supply.

Abstract: A photoacoustic effect is used in order to measure a flow rate of a flowing medium (M), in particular of natural gas. A light emitter (1) is used to produce in the medium (M) a sound wave (S) which is transmitted by the medium (M) and detected by a sound detector (2). The light emitter (1) is less exposed to the medium (M) than a diaphragm such as used in the ultrasonic method.

Abstract: The present invention discloses a capacitive filling-level sensor, which is suitable in particular for filling-level determination in oil separator tanks. The capacitive sensor includes a measuring probe with at least one sensor electrode. According to the invention, the measuring probe is at least partially sheathed with at least one outer layer of a fluorinated plastic and at least one inner layer of a mica-filled plastic. Important exemplary embodiments concern an outer layer of perfluoroethylene-perfluoropropylene copolymer (FEP), an inner layer of mica-coated glass fiber tape impregnated with epoxy resin and possibly silanized and an incompressible, thermally adapted filling of the measuring-probe pipe with silicone oil and glass spheres or glass polyhedrons and/or an inner rod of AlMgSi-filled epoxy resin. The sheathing is electrically insulating, chemically inert, hydrophobic, oleophobic, waterproof, mechanically robust and easy to produce.