GB546472A - Temperature compensators for pressure actuated indicators - Google Patents

Abstract

546,472. Pressure gauges. BENDIX AVIATION CORPORATION. Jan. 13, 1941, No. 484. Convention date, March 7, 1940. [Class 106 (ii)] A pressure-responsive device or indicating instrument such as a rate of climb indicator, aneroid altimeter, manifold pressure gauge or air-speed indicator is compensated for temperature changes by the action of a material such as powdered carbon which absorbs or liberates gases in response to temperature variation. As shown applied to a rate of climb indicator, the interior of the pressure-responsive element 14 is connected by a tube 60 to a chamber 57 containing powdered carbon 59 and a further tube 24 communicates with the atmosphere by way of a coupling chamber 25 and outlet 48. The casing 38 is substantially sealed but communicates with the outside atmosphere by porcelain diffusing tubes 53 (one only shown) as described in Specification 507,991. In operation, with an increase in altitude equalization of pressure within the casing 38 is delayed by the porcelain diffusing tubes, and the consequent difference of pressure inside and outside the pressure-responsive element 14 adjusts a pointer 36 to indicate the rate of climb or descent. If a change of temperature occurs (the altitude remaining constant) the pressure of air within the casing 38 changes owing to the slow escape through the diffusing tubes, and the carbon 59 being subjected to the same change of temperature adsorbs or liberates air to an extent sufficient to equalize the pressures within and without the pressure-responsive element thus avoiding a false reading. In a modified arrangement, the carbon chamber 57 is connected to the interior of the pressureresponsive element 14 by way of the coupling chamber 25. Specification 530,171 also is referred to.