A Study on Statostat-Type Pressure Difference Measuring Device

The principles of this measuring method are based on the fact that air confined in a vessel to keep a strictly constant temperature is also kept at a constant pressure (reference pressure). The ventilating pressure, therefore, may be obtained from the pressure difference between the reference pressure and atmospheric pressure at opposite sides of the tunnel. In order to keep a constant air temperature in the vessel, the vessel is placed in a container which is controlled at about 40°C by means of on-off regulation of a heater. From this temperature regulation of the container and heat transfer characteristics of the vessel, the air can be structurally kept at a constant temperature within a high accuracy, 0.006°C. Accuracy of this measuring method practically, is evaluated from the correspondence between measurement of the pressure difference produced from the known height difference and the pressure difference obtained from the product of density of the atmosphere and its height difference.