摘要:
A dew-point sensor for a dew-point measuring device for measuring the water vapor dew point in gases comprises a sensor surface which is exposed to the gas to be measured and on which on cooling to the dew-point temperature water vapor condenses. Mounted on the sensor surface are two electrode structures which comprise electrode portions which are arranged a uniform interval parallel to each other and which are covered with a moisture-insensitive insulating layer. The reaching of the dew-point temperature is determined by measuring the impedance or capacitance between the two electrode structures. The distance between the electrode portions, arranged parallel to each other, of the two electrode structures is of the order of magnitude of the diameter of the largest condensation droplet forming on reaching the dew-point temperature, or smaller than said diameter, and the thickness of the insulating layer is small compared with the distance between the electrode portions.
摘要:
For measuring the water vapor dew point in gases, a moisture-dependent electrical quantity of a sensor surface suitable for indicating formation of dew droplets is held by temperature control at a desired value corresponding to a stable dew mass. The temperature of the sensor surface corresponding to the desired value of the moisture-dependent electrical quantity is measured as dew point temperature. For compensating the influence of soiling, from time to time the desired value of the moisture-dependent electrical quantity is set in that the temperature of the sensor surface is lowered from a value lying above the dew point temperature and a periodic time temperature variation superimposed on the lowering. If the sensor surface is soiled, periodic time variations of the moisture-dependent electrical quantity occur at the same time but they become a monotonic variation when the dew point temperature is reached. The value of the moisture-dependent electrical quantity measured on the transition of the periodic time variations to a monotonic variation is then used as the reference or desired value which is maintained by the control of the temperature of the sensor surface. Furthermore, the control parameters for controlling the moisture-dependent electrical quantity are continuously corrected on the basis of an oscillation analysis.
摘要:
The temperature measuring circuit includes a plurality of temperature sensors, each of which is formed by a temperature-dependent measuring resistance having two current terminals and two voltage tapping terminals arranged in each case between an associated current terminal and the temperature-dependent measuring resistance. The temperature sensors are connected via the current terminals in series and the series circuit is connected via two current conductors to an evaluating circuit which sends a constant current through the measuring resistances connected in series. For measuring the voltage drops caused by the constant current at the individual measuring resistances the voltage tapping terminals of each temperature sensor are connected by voltage conductors to the evaluating circuit. The two voltage tapping terminals of two temperature sensors following each other in the series circuit and assigned to two interconnected current terminals are each connected via a resistance to a common voltage conductor. This results in a considerable saving of connecting conductors compared with a temperature measuring circuit with the same number of temperature sensors each connected by two current conductors and two voltage conductors to the evaluating circuit.
摘要:
A pressure transfer device comprises a pressure transfer device body and an isolating diaphragm, wherein, between the surface of the body of the pressure transmitting device and the isolating diaphragm, a pressure chamber is formed, whose volume is dependent on the position of the isolating diaphragm. The isolating diaphragm has a material thickness and a deflectable working region with an area A, wherein the isolating diaphragm has a reference position, in which the pressure chamber contains a reference volume Vref, and the isolating diaphragm is deflectable from the reference position at least so far in two directions, that the volume of the pressure chamber varies between values of up to Vref+/−ΔVdesired, wherein associated with a volume change ΔV is a dimensionless deflection measure w, with w(ΔV):=(3·ΔV)/(A·h), wherein ΔVdesired is dimensioned in such a way, that |w(ΔVdesired)|≧2.5; wherein, in the case of all w(ΔV), for which |w(ΔV)|≦|w′(ΔV)|, wherein |w′(ΔV)|≧0.5·|w(ΔVdesired)|, the isolating diaphragm has a non-axisymmetric deflection mode, which is superimposed on the axisymmetric deflection of w(ΔV), and wherein the deflection of the non-axisymmetric deflection mode, in the case of |w(ΔV)|=0.4·|w(ΔVdesired)|, amounts to at least 0.3 times the maximal deflection of the non-axisymmetric deflection mode.
摘要:
A pressure transfer device comprises a pressure transfer device body and an isolating diaphragm, wherein, between the surface of the body of the pressure transmitting device and the isolating diaphragm, a pressure chamber is formed, whose volume is dependent on the position of the isolating diaphragm. The isolating diaphragm has a material thickness and a deflectable working region with an area A, wherein the isolating diaphragm has a reference position, in which the pressure chamber contains a reference volume Vref, and the isolating diaphragm is deflectable from the reference position at least so far in two directions, that the volume of the pressure chamber varies between values of up to Vref+/−ΔVdesired, wherein associated with a volume change ΔV is a dimensionless deflection measure w, with w(ΔV):=(3·ΔV)/(A·h), wherein ΔVdesired is dimensioned in such a way, that |w(ΔVdesired)|≧2.5; wherein, in the case of all w(ΔV), for which |w(ΔV)|≦|w′(ΔV)|, wherein |w′(ΔV)|≧0.5·|w(ΔVdesired)|, the isolating diaphragm has a non-axisymmetric deflection mode, which is superimposed on the axisymmetric deflection of w(ΔV), and wherein the deflection of the non-axisymmetric deflection mode, in the case of |w(ΔV)|=0.4·|w(ΔVdesired)|, amounts to at least 0.3 times the maximal deflection of the non-axisymmetric deflection mode.