Abstract: A flow meter is provided which employs a thermal flow sensor and a correcting flow meter, for example, a Karman vortex flow meter such that the output from the thermal flow sensor is corrected by the Karman vortex flow meter, thereby making it possible to accurately and stably measure the flow rate of fluids in a wide range even if the composition of fluids changes.

Abstract: In this sensitive, relatively inexpensive to manufacture, photo-detector, one surface of an amorphous silicon photovoltaic element is bonded to a thin transparent conductive layer formed on an insulating base. A conductive pattern is formed on the opposite surface of the element. The conductive layer may be formed of indium-tin oxide (ITO) and the photovoltaic element may be an element with an intrinsic semiconducting layer between p and n doped layers. The photovoltaic element generates component currents in response to photons passing through the transparent base and conducting layer. Those current components flowing predominantly in a direction at right angles to the photovoltaic element surfaces are summed by the conductive pattern which acts as a spatial filter, responsive to desired ones of these components and relatively unresponsive to other current components.

Abstract: A fluid flow speed measuring apparatus comprising a first pipe having an opening exposed into a fluid to be measured, a direction of the opening having an angle larger than a critical negative pressure angle, a second pipe having an opening exposed into the fluid to be measured, a direction of the opening of the second pipe having an angle larger than the critical negative pressure angle and at least one of conditions such as a diameter, a direction, and the number of the openings for determining a magnitude of the negative pressure being different from that of the opening of the first pipe, negative pressure difference detector for detecting a difference between negative pressures acting on the openings of the first and second pipes, and device for calculating a flow speed of the fluid to be measured on the basis of an output from the negative pressure difference detector.

Abstract: A calorimetric apparatus for determining the calorific content of a fuel gas uses a reactor for producing oxidation of the fuel gas and a combustion gas in the presence of a catalytic oxidizer. The oxidizer is heated by a constant current supply to a catalytic oxidation temperature. The resistance of the catalytic device is measured before and during the oxidation reaction which produces an additional heating of the catalytic device. The change in resistance is used to control a valve arranged to determine the flow rate of the fuel gas to the reactor. A display control signal is derived from a valve control signal and used to control a display for indicating the calorific content of the fuel gas.

Abstract: A calorimetric apparatus for determining the calorific content of a fuel gas uses a reactor for producing oxidation of the fuel gas and a combustion gas in the presence of a catalytic oxidizer. The catalytic oxidizer is mounted on one end of a thermo-electric element which element has a heat absorbing end and a heat emitting end when energized by an electric current to produce a Peltier effect. The catalytic end of the element is mounted within the reactor while the other end is located outside of the reactor. The temperatures of the ends of the element are detected by a controller and the difference therebetween is maintained at a predetermined level during the catalytic reaction by the controller developing a control signal to control the supply of the electric current to the element. A display control signal is derived from the control signal by the controller and used to control a display for indicating the calorific content of the fuel gas.